Information

What insect is this? (India)


Can anyone tell me what kind of insect (if it is one) is this… !! Or is it the pupa of some insect?

Well I don't think that the whole big thing is the insect itself, it appears to be just a kind of protection or shelter which moves along with the tiny little thing that keeps on popping out and going it so as to move.

Location: India


This is mostly a guess and loose suggestion, since the picture is not very clear (would need to see the larvae in more detail). However, Bagworm moths (Psychidae), Case moths (Coleophoridae) and Caddisfly larvae (Trichoptera, almost exclusively aquatic) all build similar cases. They construct their cases out if silk and often include debris, pebbles and other materials. I wouldn't be surprised if the larvae in your picture belongs to one of the first two taxa. Bagworm moths and Caddisflies generally include lots of external materials in their larval cases, which could point to Case moths for your specimen (which seems to have a weaker case mostly made of silk).

Here are two pictures of first a UK Case moth larvae (Coleophora deauratella) followed by a Bagworm moth (Dahlica triquetrella), just as comparisons. If you do google image searches of "group name + larvae" you will see many examples of what they can look like.

And just as a cool example - the larvae often use random material lying around to build their cases, which can give the following result, if caddisfly larvae are bred in a tank containing pieces if gold and pearls. For further information see this link.


It's a household casebearer, a kind of moth larva in the family Tineidae that builds this case around itself.

@fileunderwater is wrong


Entomophagy

Entomophagy ( / ˌ ɛ n t ə ˈ m ɒ f ə dʒ i / , from Greek ἔντομον éntomon, 'insect', and φαγεῖν phagein, 'to eat') describes a feeding behaviour that includes insects. Aside from non-human creatures, the term can also refer to the practice of eating insects among humans.


Major Insect Pests that attack Banana Tress in India and their Control

One of the oldest fruit know to human kind is banana or plantain. They belongs to genus Musa. Several species of this genus (Musa chinensis, M. paradisiaca, M. sapientum) are found in different parts of India, Burma, China, Thailand etc. Banana is also grown m tropical parts of Africa, America, Australia and Philippines. In India, cultivation of banana started as early as 600 B.C.

The tropical conditions are most suitable for banana growth. In India, the major banana producing states are Kerala, Tamil Nadu, Maharashtra, Gujrat and Assam. Ripe banana contains a good quantity of carbohydrate and a fair amount of calcium, phosphorus and iron, also contains appreciable quantity of vitamin С and minerals. Banana is considered as energy producing food, unripe banana is used for cooking and extracting beer.

Different insect pests have been reported from different parts of the world which are destructive to banana crop. However, In India, only few pests actually causes serious damage to the banana tree.

1. Cosmoplites Sordidus, Germere (The Banana Weevil):

It is found in all banana growing countries of the world but have not been reported from Egypt, Israel, and Hawaii. In India, it is found throughout the country, especially in Tamil Nadu, Kerala, Karnataka, Maharashtra, Gujrat, Punjab, Rajasthan, Bihar, Orissa, West Bengal, Uttar Pradesh and Andhra Pradesh.

It is one of the most destructive pests of banana. Both adults and grubs cause damage to the banana tree. The adult feed on the pseudo stems and grubs on the rhizome (the visible aerial part of banana is pseudo stem which is extension of the underground part, rhizome).

The pseudo stem get riddled with holes while the growing point of rhizome is destroyed, resulting in premature withering and failure of appearance of new suckers (shoots), respectively. The surviving plant produces undersized fruits. The tunnels made by weevils are occupied by bacteria and fungi, which accelerates the process of rotting.

Marks of Identification:

The stoutly build adult weevil is about 10 to 13 mm in length. The body is black or reddish-brown with arterially elongated and slightly curved snout. Short elytra are longitudinally striated.

Oviposition occurs throughout the year. Eggs are laid singly in exposed part (collar) or underground part of the rhizome. Female makes small burrows by scooping out the tissues or within the leaf sheath. Egg hatches into grubs in 5 to 8 days.

The grub is apodus (legless), yellowish, fleshy, spindle shaped with reddish head. The body measures 8 to 12 mm in length. It bores into the rhizome and tunnels within it, feeding upon the rhizome tissues.

Larval life takes about 25 days, after that pupation occurs within the tunnels formed by grubs near the outer surface of the rhizome. Pupation lasts for 5 to 6 days. Pupation may also occur in soil. Adult emerges out of the pupa and hide itself into the leaf sheath of pseudo stem, feeding on its internal tissues. Adults generally feed during night. They survive for one to two years and can remain without food for six months.

Control:

1. Clean cultivation help in reducing the weevil population.

2. The infested suckers should be uprooted and destroyed.

3. Uninfected suckers to be used for plantation.

4. The cut portion of pseudo stem after fruit removal should be covered with layer of earth.

5. At the time of planting, the pits should be treated with 5% BHC dust @ 60-80 g per pit.

Spraying around the collar with Fenitrothion (0.1%) or 0.05% dieldrin or 0.05% endosulfan 0. 05% phosphamidon, 0.05% chlorpyriphos etc.

2. Odoiporoxjs l ongicollis, Olivier:

(The Banana Stem Borer)

It is a serious pest of banana reported from countries like India, Burma, Sri Lanka, Bangladesh and Indonesia. In India, it is more prevalent in states like Bihar, West Bengal and Assam (North-East India).

The grubs are more destructive. After hatching the grubs feed on tissues of leaf sheath and then bore its way into the pseudo stem.

Large number of grubs enters into a single plant, making the pseudo stem weak which starts rotting and ultimately the tree break down when faces strong wind. Adult insect too, feed on leaf sheath tissues, especially the decaying ones.

Marks of Identification:

The adults are robust, reddish-brown or black weevil, measuring 1.3 to 2 cm in length.

The adult male and female after emergence mate either outside the tree or within the leaf sheath. Pre-oviposition period lasts for 28 to 30 days. The pest breeds throughout the year but remain more active during summer and monsoon months.

Female by its rostrum make slit into the l.eaf sheath and thrust the eggs within the air chambers. A single egg is laid in one chamber. Eggs are cylindrical, yellowish-white, measuring 2 x 1 mm. Egg hatch in 3 to 5 days in summer and 5 to 8 days in winter. Larva is legless (apodus), soft bodied, fleshy, wrinkled and covered with brown hairs.

Larval life is about 26 days in summer and 68 days in winter. There are five larval instars. Larva bores into pseudo stem making tunnels within it. This causes weakening and decomposition of affected part.

Fully grown larvae cocoon by winding short fibrous materials of leaf sheath around it. It pupates inside the tunnel near the periphery of the pseudo stem. Pupal period lasts for 20 to 24 days in summer and 37 to 44 days in winter. The adult feeds on the inner part of the leaf sheath and on decaying tissues. It lives for about two years.

1. Uprooting and burning of infested plant.

2. Cleaniness and improved field sanitation reduces the pest population.

3. Inserting alminium phosphate tablets into the thick basal regions of pseudostems @ 1.5 g for each pseudostem (as suggested by Dutt and Maiti, 1972) prevents pest attack.

Spraying carbaryl (0.2%) or Endosulfan (0.05%) periodically, keeps the population of the pest under control.


Major Insects Pests that attack Guava Trees in India and their Control

Guava (Psidium guajava) is a common fruit of Indian sub-content. It is a native of tropical America. In India, it was introduced in 17th century and is now a household fruit especially in Uttar Pradesh and Bihar.

The fruit is eaten in its raw form. Immature fruits are not edible however mature and ripe fruits are relished by people of different age groups. Guava juice is used for making jam, jelly, fruit butter and sugar syrup.

Through grafting and hybridization different varieties of guava have been developed. Guava trees are hardy as it can withstand draught and tolerate varying soil conditions. Guava contains fair amount of carbohydrate phosphorus, calcium and iron. The fruit is very rich in vitamin С and vitamin A. More than 80 species of insects have been observed which, in one form or another, affect the quality and yield of guava however few of them cause serious damage.

1. Dacus (= bactrocera) dorsalis hendel:

Dacus dorsalis is a major pest of guava and mango. It also infests brinjal chillies, apricot, sapota, ber etc. This pest is found all over India.

Both adult and maggote cause damage to the fruit. The maggots destroy the pulp which in turn becomes discoloured and produce foul smell. Brown rotten patches appear on the attacked fruit which eventually falls down. Adult feeds on exudations of ripe fruit. The puncture produce by female on the surface of fruit for egg laying makes way for the micro­organisms to enter inside the fruit.

Marks of Identification:

The insect is light brown with transparent wings and yellow legs. 1 he fruit fly is little larger than the house fly and is stoutly build.

Female laid eggs on the soft skin of the ripening fruits. The eggs are inserted under the rind of the fruits. The adult flies emerge out in the month of April and starts laying eggs. The process of egg lying continues for about four months i.e., till July. The eggs are laid in clusters of 2 – 15 on the host fruits. During the adult span of four months a female laid 600 to 800 eggs.

The maggots that emerge from the eggs feed on the ripe pulp of the fruit. Larval life lasts for 6-44 days. The mature maggote comes out of the fruit and drop on the ground to form pupa. Pupa formation occurs 4 to 6 inches below the surface in the soil. Pupal life lasts for 6-29 days. Adult emerges out from the pupal case. They are good fliers.

Control:

1. The fallen and infested fruits should be collected and buried deep into the soil.

2. Ploughing around trees to expose pupa to be destroyed by heat and predators.

1. The adult flies may be trapped and killed by poison baiting or bait spray (20 ml malathion + 200 g molasses in 20 liters of water)

2. The hedges around the guava trees may be sprayed with endosulfan (0.1%), carbaryl (0.1%) or Quinalphos (0.05%).

2. Indarbela tetraonis moore:

(Bark Eating Caterpillars/The Shoot and Bark Borer)

It is a common pest of guava and is widely distributed all over the Indian sub­continent. Although, this pest is found in several parts of India like Bihar, Orissa, Haryana, Rajasthan, Madhya Pradesh, Maharashtra, Andhra Pradesh and Tamil Nadu, it is more common and destructive on guava trees especially in Punjab, Uttar Pradesh and South India.

Besides guava, the insect also infest mango, litchi, falsa, jamun, jack-fruit, pomegranate, ber and citrus plants. Damage is caused by the caterpillars. The caterpillar bore into the bark and stem as deep as 15 to 25 сm and feed on bark tissues. The conducting tissues are destroyed affecting the growth of the tree and fruit yield.

The caterpillar remains hidden in the bore hole during daytime. At night, it comes out and feed on the bark of the tree. The larva covers the bore hole and surrounding area by silken web, which provides protection and shelter to the pest while feeding. A single larva inhabits a bore hole however there may be 15 to 30 larvae in a single tree. Holes on the stem surface and silken galleries full of faecal matter and frass indicates the presence of the pest.

Marks of Identification:

The adult insect is short, stout pale-brown moth. The fore wings bear deep brown vertical markings while the hind wings are greyish-white. The wing span is 46 to 50 mm in case of female and 35 to 38 mm in case of male.

Egg lying commences from April to June. Female laid eggs in cuts and crevices in the bark of the host tree in clusters of 15 to 25. In 8 to 10 days larvae hatches out of eggs.

For sometimes the larva feed on the bark. They form a ribbion chips and produce silken threads on the bark surface. The more advanced larva bore into the wood making short tunnels in the stem. During daytime the larva remain inside tunnel but in night comes out to feed on the bark.

A fully grown larva is dirty brown in colour and measure 38 to 45 mm in length. The larval life lasts for 10 to 11 months. After that the larva pupate inside the galleries during March — April. Pupal period lasts for 15 to 25 days. Adult emerges out from pupa. There is a single generation in a year.

1. The frass and faecal matters along with ribbon like silken web should be scrapped from the bark and bum, so that caterpillars hidden under them are destroyed.

2. Hot water may be inserted in the bore hole through syringe.

1. After removing frass and faecal matter from tree bark, 0.1% emulsion of quinalphos or 0. 05% chlorpyriphos should be sprayed.

2. Injection of enderin (0.04%) or BHC (0.2%) or DDT (0.5%) and endosulfan (0.05%) into the hole can kill the larva present inside the stem.

3. Cotton wool soaked in carbondisulphide, chloroform or petrol should be inserted into the holes on tree bark. The opening of the hole may then be covered with mud.


Economic Importance of Insects

Insects which produce honey, wax, lac, dyes and silk are commercially beneficial. Some insects are very helpful in destroying injurious insects.

1. Commercial Products:

Apis, the honeybees produce millions of tons of honey every year, it also gives bees wax from its combs.

Benefits of bees are cosmopolitan, not only in producing honey and wax, but also in bringing about cross-pollination of many fruits and flowers without which these plants could not exist. Tachardia, the lac insect secretes commercial lac produced from integumentary glands as a protective covering by females, shellac is made from lac in India.

Dactylopius, the cochineal insect of Mexico is found on cacti, dried bodies of females of this scale insect are used for making cochineal dyes. Bombyx and Eupterote are silk moths, they are reared in India, China, Japan and Europe, their larvae called silk worms spin cocoon of raw silk, the silk fibre is reeled off and used for making silk.

In Asiatic countries over 25 million kilograms of silk are produced annually. Dried elytra of two beetles, Lytta and Mylabris are used for making cantharidin, a powerful aphrodisiac.

The larvae of two flies, Lucilla and Phormia are used in healing such wounds of bones which do not respond to medicines, the larvae are put in wounds of bones and bone marrow, they clear away suppurating and dead tissues, prevent bacterial growth and excrete allantoin which heals the wounds.

2. Useful Predaceous Insects:

Some insects are predaceous, they feed upon and destroy a large number of injurious insects. Stagomantis, a mantis is voracious, it feeds on flies, grasshoppers and caterpillars, some of which are injurious to crops. The larvae and adults of Chilomenes, a lady-bird beetle, feed on aphids which infect cotton plants.

Novius, a lady-bird bettle, destroys scale worms which are pests of orange and lemon trees. Epicauta is a blister beetle, it deposits eggs where locusts occur, the larvae on hatching enter egg capsules of locusts and eat up masses of eggs. Calasoma, a ground beetle preys upon many kinds of lepidopterous larvae which destroy cereals and cotton.

3. Beneficial Parasitic Insects:

Some insects parasitise injurious insects, they usually lay eggs in the bodies of larvae and adults of harmful insects the young on hatching from eggs finally kill their hosts. The larvae of Tachina and related flies are parasites of injurious lepidopterous larvae, such as army-worms which are injurious to cereals.

Larvae of hymenopteran flies and carnivorous wasps devour aphids in large numbers. Chalcids and ichneumon flies are parasitic, laying eggs in cocoon and larvae of phytophagous Lepidoptera. Apanteles, a hymenopteran fly lays eggs in army-worms and boll worms, the parasitic larvae gnaw their way through the skin of the host.

4. Scavengers:

Some insects are scavengers, they eat up dead animal and vegetable matter, thus, they prevent decay. Some ants and larvae of some flies can devour entire animal carcasses.

B. Injurious Insects:

Compared with beneficial insects the number of injurious insects is very large.

1. Disease Transmitting Insects:

Many types of mosquitoes, flies, fleas, lice and bugs transmit diseases to man and domestic animals, they have been described earlier in insects and diseases.

2. Household Insects:

Human food is spoiled by cockroaches, ants, flies and weevils. Tinea, Teniola and Trichophaga are clothes moths, they lay eggs on warm clothes, the larvae on hatching eat and destroy clothes, they also feed on furs, carpets and dry fruits. Anthrenus is a carpet beetle, it is a scavenger eating decaying animal matter, but its larvae destroy carpets and preserved biological specimens.

Tenebrio is the mealworm beetle, its larvae are mealworms, they eat meal, flour and stored grains, such as rice. Lepisma, the silver fish and Liposcelis, the book louse live in and destroy books and old manuscripts. Termites, the white ants cause untold destruction of books, carpets, furniture and wood-work of buildings.

3. Injurious to Domestic Animals:

Glossina, the tsetse fly transmits Trypanosoma brucei which causes nagana in horses. Tabanus and Stomoxys, the blood sucking flies inject Trypanosoma evansi into horses and cattle which causes surra in India.

The larvae of Hypoderma, the warble fly bore below the skin of oxen and make holes for breathing, then they pass through the gullet and again pierce the skin on the sides of the spine to form swellings, they not only injure the hide but also reduce the meat and milk supply.

Gasterophilus, the bot-fly lays eggs on hair of horse, the larvae enter the stomach in large numbers. Melophagus, the sheep tick and Hippobosca, the forest fly of cattle and horses suek blood of their hosts and often cause haemorrhage. Menopon, the chicken louse sucks blood and causes destruction of fowls.

4. Injurious to Crops:

Many insects damage forest trees, growing farm crops, fruits and stored grain, the damage they cause annually runs into millions of rupees.

The number of such insects is innumerable, they are mostly Lepidoptera, Coleoptera, Diptera and Hemiptera. Euproctis, the brown tail moth and Lymantria, the gipsy moth are serious pests of shade and foliage trees, their larvae are a menace and destroy forest trees. Myetiola, the Hessian fly is a small sized midge, its larvae damage wheat plants.

The larvae of two Lepidoptera Chilo in India, and Diatraea in America bore into stems of sugar-cane and cause a great deal of damage. Pyrilla, a hemipteran sugar-cane leaf hopper sucks the juice of sugar-cane, both as adult and nymph, causing great loss of sugar.

Pyrausta is a moth found all over the world, but specially abundant in the tropics, its larvae known as corn borers are notorious for boring into stems and fruits of corn (maize). Nephotettix, the Indian rice leaf-hopper and Leptocorisa, the oriental pest of rice and millet are Hemiptera, they attack rice in very large number eating the leaves and ears.

The larvae of Schoenobius, a moth bore into the stems of rice plants in India, they kill the plants. Nymphs and adults of Hieroglyphus, an orthopteran eat up the growing shoots of rice plants, thus, preventing formation of grain.

Dysdercus, the Indian cotton bug, Oxycarenus, the Egyptian cotton bug, and Anthonomous the cotton-boll weevil are very injurious to cotton, they stain and destroy cotton- bolls, Aphis, a hemipteran is a serious cotton pest in India, the pests often attack cotton plants in large numbers causing the plants to wilt and die.

The larvae of two Lepidoptera, Agrotis and Gnorimoschema are potato cut-worms in India, the former feeds on potato leaves and cuts off the stems, while the larvae of the latter eat the potatoes in the field and stores, larvae also attack tobacco and tomatoes. Larvae of Agrotis are also destructive to peas, cabbage, tobacco, ground nuts, wheat and cauliflowers.

The larvae of some Coleoptera are called wire-worms, such as Agriotis and Limonius, they are root-feeders and are extremely destuctive to cereals, root crops and grasses. Many insects and their larvae destroy vegetables in India.

Siphocoryne is an aphis which feeds on cabbage leaves Anasa, the squash bug is destructive to cucurbitaceous plants Earias the spotted bollworm destroys ladyfingers Aulacophora, the red beetle feeds on pumpkins the larvae of Bruchus, a beetle bore into pods of beans and peas killing the seed.

Many insects attack fruit trees, they damage roots, trunks, stems, leaves, inflorescence and fruit. Drosicha, a mealy bug causes destruction of mangoes, plums, papaya, jack fruit, pears and citrus fruits in India. The nymphs and adults of Ideocerus, a mango leaf hopper attack the inflorescence and suck the sap, thus, they cause tremendous damage by preventing formation of mango fruit.

The laryae of Contarinia fly feed on young pears which soon decay. Psylla, an apple bug, lays eggs on apple and pear tree, the nymphs on hatching damage the blossom and shoots the larvae of Anthonomus, a beetle also destroy apple blossoms and prevent formation of the fruit. Nysius, a bug is very destructive to several kinds of fruit trees.

Many moths, caterpillars and beetle cause a great deal of damage to stored grains: two beetles Tenebrio and Tribolium have similar habits and are commonly found in stores and granaries, the former is found in all stages in meal, flour and stored goods, its larvae are known as meal worms. Tribolium eats stored wheat and grain. Calandra, a weevil bores through grains of rice and other stored grain in India.


Introduction

Ecologists have long recognized the role of terrestrially derived inputs of plant material and invertebrates to streams however, more recently the focus has turned to the flux of materials and organisms in the opposite direction, from stream to land (Baxter et al., 2005, Sabo & Hoekman, 2015). The emergence of aquatic insects in an aerial adult form represents an important link between streams and adjacent riparian habitats, facilitating the flow of energy and nutrients from aquatic to terrestrial food webs. Adult aquatic insects are important food subsidies for a range of riparian predators, including lizards, birds, bats, and spiders (Baxter et al., 2005). Some estimates indicate that only about 3 percent of emerged aquatic insect biomass returns to the stream to lay eggs because the majority is consumed (Jackson & Fisher, 1986). The focus here is on one specific predator, the spider, because it is relatively easy to observe and identify. Populations of various spiders are known to closely track aquatic insect emergence (Marzcak & Richardson, 2007). The family Tetragnathidae, because of its high mobility, can exploit short periods of emergence in localized areas. In fact, spider counts may be a useful method for assessing stream integrity and habitat quality, and are less labor-intensive than other sampling methods that focus on invertebrates or fish (Benjamin et al., 2011).

We present a guide for an inquiry-based laboratory and field lesson for undergraduate biology courses at any level. Students should have a basic understanding of the scientific method and a high school biology level background, but with more detail added, this lesson can be used to teach students with no preexisting knowledge of the topics covered. The focus is on cross-habitat linkages within ecosystems, specifically addressing the question, What is the role of insect emergence in connecting aquatic and terrestrial habitats and organisms? The challenge is to change how students think about the environment we live in: not as an organized puzzle built from discrete pieces with defined boundaries, but rather as a colorful soup, composed of multiple layers of flavor and a taste that becomes more defined the longer you stir it.


Brood X Cicadas Are Emerging at Last

Kate Wong is a senior editor for evolution and ecology at Scientific American.

Cherie Sinnen is a freelance illustrator based in California.

A t this very instant, in backyards and forests across the eastern U.S., one of nature&rsquos greatest spectacles is underway. Although it may lack the epic majesty of the wildebeest migration in the Serengeti or the serene beauty of cherry blossom season in Japan, this event is no less awe-inspiring. I&rsquom talking about the emergence of the Brood X cicadas.

Every 17 years the billions of constituents of Brood X tunnel up from their subterranean lairs to spend their final days partying in the sun. This generation got its start back in 2004, when Facebook existed only at Harvard University and Friends aired its last episode. The newly hatched cicada nymphs fell from the trees and burrowed into the dirt. They have been underground ever since, feeding on sap from the rootlets of grasses and trees and slowly maturing. All of that preparation has been leading up to this moment when they surface in droves&mdashup to 1.4 million cicadas per acre&mdashto molt into their adult form, sing their deafening love song and produce the next generation before dying just a few weeks later.

To early European settlers in North America, the sudden appearance of these insects in large numbers brought to mind the locusts of biblical infamy. But whereas locusts are grasshoppers that form giant swarms and travel long distances, devouring crops on a devastating scale, cicadas belong to an entirely different order of insects. They do not swarm and are poor fliers, typically traveling no more than several hundred feet. Moreover, they pose little threat to plants because they do not eat plant tissues. Females do make incisions in twigs for their eggs, which can weaken saplings but not mature trees and shrubs.

Nearly 3,400 species of cicadas exist worldwide. But periodical cicadas that emerge en masse once every 17 or 13 years are unique to the eastern U.S. The 17-year cicadas live in the North, and the 13-year cicadas are found in the South and the Mississippi Valley. The three species of 17-year cicadas&mdashMagicicada septendecim, M. cassinii and M. septendecula&mdashform mixed-species cohorts called broods whose members arise like clockwork on the same schedule. The broods are identified by Roman numerals. Brood X is the largest of the 12 broods of 17-year cicadas, which emerge in different years.

The periodical life cycles of these cicadas, with their long developmental phases and synchronized emergences, have long captivated scientists. Most other cicadas studied thus far have life cycles of three to five years, says Chris Simon of the University of Connecticut. Their nymphs grow at different rates depending on genetic and environmental factors, and they stage their exit from underground once they reach a certain body size and level of development. As a result, the offspring of any one female come out in different years, she explains. Periodical cicadas, in contrast, stay belowground for a fixed amount of time, regardless of when they reach full size, and then emerge together.

Exactly how periodical cicadas came to have these unique life history patterns is an area of active research. DNA analyses suggest an approximate time line of their evolution. The last common ancestor of all living Magicicada species branched into two lineages around 3.9 million years ago during the Pliocene epoch. One of these branches itself diverged 1.5 million years later during the Pleistocene. The three resulting lineages ultimately gave rise to the seven species of 13- and 17-year cicadas alive today. Why these cicadas settled on 13- and 17-year schedules is unknown. One hypothesis holds that having long, prime-number cycles might boost their odds of survival by offsetting their emergence from predator-population booms that occur more frequently and on composite-number cycles. But the two other known periodical cicadas&mdashone in Fiji and the other in India&mdashemerge at eight- and four-year intervals, respectively.

Researchers have proposed that periodical cicadas evolved from nonperiodical cicadas by trading a size-based emergence schedule for an age-based one and extending the development period. Climate change probably helped drive this shift. Periodical cicadas are sensitive to temperature&mdashit determines the length of the growing season. During the Pleistocene, cooling temperatures would have slowed juvenile development on average but increased the variation in the growth period, making the timing of adult emergence in ancestral cicadas even more variable than before. With the resulting reduction in the density of adult cicadas emerging in any given year, mating opportunities would have dwindled. Under such conditions, switching from a size-based emergence strategy to an age-based one in which the insects remain underground for a long time and then surface simultaneously would increase the adult population density at emergence and thus their opportunities to find mates and reproduce.

Emerging simultaneously in huge numbers also overwhelms predators. Consequently, even after the birds, mammals and fish have sated themselves on the plump, defenseless insects, plenty of cicadas remain to produce the next generation.

Climate change also shaped the distribution of the broods. As North America&rsquos ice sheets advanced and retreated over the past 20,000 years, the deciduous forests that cicadas inhabit shrank and expanded. Broods evolved in response to those cooling-warming cycles. Gene Kritsky of Mount St. Joseph University in Cincinnati, Ohio, points to Brood X in the western part of his state as an example. Twenty thousand years ago the ice sheets extended to just north of where Cincinnati is today. Because the land was covered in ice, there were no forests, and thus no cicadas, in western Ohio back then. Around 14,000 years ago, however, the ice sheet retreated north. &ldquoForests came in, and periodical cicadas came with them,&rdquo Kritsky explains. Ohio hosts three other 17-year cicada broods, each of which occupies its own region of the state. &ldquoThe distribution in Ohio of 17-year cicadas matches the physiographic regions created by the ice ages,&rdquo he observes.

Periodical cicadas have been able to adapt to climate change in part because they have some plasticity in their life-cycle length: they can accelerate or decelerate their emergence schedules by four-year increments. But this flexibility does not assure their long-term survival. Brood XI has been extinct since around 1954 others are waning. The main threat is habitat loss, according to Kritsky. In 1919 the U.S. Department of Agriculture predicted the demise of Brood X as a result of deforestation.

Mapping periodical cicada emergences helps scientists gauge how the broods are faring. Researchers have asked the public to report sightings for decades&mdashin the old days via postcard and later by phone and e-mail. Now they are crowdsourcing data with an app that Kritsky and his colleagues developed, called Cicada Safari, that allows people to submit pictures and videos of any cicadas they encounter and view a map of the Brood X emergence in real time as it unfolds. &ldquoIn 1902 the USDA based its map on just under 1,000 postcards it received,&rdquo Kritsky says. This year, through the app, &ldquowe&rsquore hoping to get 50,000 photographs.&rdquo A fitting send-off for the Brood X class of 2021.


WHAT RUSTLING INSECTS GIVE AWAY

Foraging in the dark is challenging, but not when you're equipped with echolocation. Plucking insects from the open air is simple for bats. But it's much trickier hunting at the forest edge. Detecting an insect amongst the barrage of reflections from the surroundings seems almost impossible. So how do echolocating bats locate tasty treats on the forest floor? Björn Siemers from the Max Plank Institute of Ornithology explains that some bats tune their acute hearing to the tiny rustling sounds made by insects. But how much of an effect does the material that an insect is clambering over have on the tell-tale sound it makes? And what could an approaching bat learn about its victim from its rustling? Siemers and his students, Holger Goerlitz and Stefan Greif, decided to measure sound volumes as insects scuttled across various natural surfaces to see how the landscape affects their acoustic trail( p. 2799 ).

Starting out in Germany, Siemers and Greif decided to measure the sounds made by insects as they wandered over three different surfaces a beech forest floor, a freshly mown meadow and newly ploughed earth. But the team needed to make their sensitive recordings in a completely silent environment, so they excavated 50 cm square chunks of each surface and transported them back to a soundproof room in the University of Tübingen to record the noises made by wandering carabid beetles. Equipped with exquisitely sensitive recording equipment, Greif waited patiently for the beetles to go about their everyday business, recording their tiny footsteps as they walked over each surface when dry and damp.

Analysing the recordings, Siemers found that the beetles were much nosier ambling through the beech leaf litter than the meadow or bare earth. And when he compared the sound generated by the dry surfaces with that from the same surfaces when damp, the volume doubled across all surfaces. The team also found that the rustling became significantly louder as the beetles walked faster.

But what effect did the beetles' size have on their rustling volumes?Siemers needed to find insects with a wide range of sizes and knew that the Madagascan rainforest is home to some of the most diverse populations of insects on the planet. Collecting beetles and cockroaches ranging in size from a few tens of milligrams up to 10 g, Siemers and Goerlitz recorded the sounds generated by the animals as they walked across dry leaf litter, bark or sand and found that the larger beetles made louder rustling noises. Also, the volume increase was more significant for larger creatures on noisy leaf litter than sand, with relatively small increases in the insects' size generating significantly larger sound volumes.

So what does all this mean for a ravenous bat hunting for a snack? Siemers explains that given the way sounds fade as you move further from their source,a beetle clambering over dry leaf litter could be heard eight times further away than another ambling over dry soil. He also suspects that an approaching bat could distinguish between a millipede and a six-legged beetle, but probably couldn't differentiate between a spider and a beetle. And if the bat knew a little about the nature of the surface beneath the insect, it might even be able to estimate its size, all crucial information for helping a bat to decide whether it's worth snatching that snack.


14 - The egg and embryology

Embryogenesis is the process by which a single egg develops into a multicellular individual. Many of our most important discoveries in understanding the embryonic development of animals, including humans, derive from studies that were first conducted in insects. Some of these discoveries are also now being applied in the fields of medicine and agriculture. As discussed in Chapters 12 and 13, all future offspring produced by insects derive from specialized progenitor cells called germ cells, which migrate to the gonads, where they differentiate into gametes. The gametes produced by females are called oocytes (eggs), while the gametes produced by males are called spermatozoa (sperm). Most insects begin their embryonic development when genetic material from an egg and sperm fuse through the process of fertilization to form a zygote. The zygote then divides mitotically to produce all of the different cells that comprise the body of the nymph (exopterygote/hemimetabolous species) or larva (endopterygote/holometabolous species), which will hatch from the egg. Embryogenesis proceeds through a similar series of steps in most insect species, but there are also a number of variations that in some cases are associated with unique life histories. In this chapter we first summarize key morphological and functional features of insect eggs (Section 14.1). Next we discuss the process of embryogenesis, including some of the molecular mechanisms that control axis formation and nutrient acquisition (Sections 14.2 and 14.3). We then consider sex determination (Section 14.4) and end the chapter by discussing parthenogenesis (Section 14.5), pedogenesis (Section 14.6) and other unique forms of embryonic development.

Most insects produce large eggs relative to their own size. This is due to a majority of insects packaging their eggs with large amounts of yolk, which serves as the source of nutrients for growth and development of the embryo. In general, the eggs of Endopterygota contain less yolk and are smaller than those of Exopterygota. To some extent this may reflect differences associated with ovariole type (Section 13.2.1). For example, in two locust (Orthoptera) species, which have panoistic ovarioles, each egg weighs about 0.5% of female weight among insects with telotrophic ovarioles, the egg of Trialeurodes vaporarium (Hemiptera) is over 1% of the female weight and that of Callosobruchus maculata (Coleoptera) 0.6%. By contrast, among insects with polytrophic ovarioles, comparable figures for Apis mellifera (Hymenoptera) and Grammia geneura (Lepidoptera) are 0.07% and 0.11%, respectively.


Results

Effect of temperature on biological parameters of D. indica

The results showed that temperature had a significant effect on the developmental time of different immature and adult stages, i.e., egg, 1st instar larvae, 2nd instar larvae, 3rd instar larvae, 4th instar larvae, 5th instar larvae, prepupa, pupa, adult, male adult, female adult, total developmental period of larvae, egg to adult emergence (developmental time), and egg to adult death (total). In the 1st, 2nd, and 5th larval instars, prepupae, and total larval period, developmental period increased slightly as temperature moved from 25 to 30஬, and then decreased at 35஬ ( Table 1 ). Our results are in agreement with the results of Peter and David (1992) . However, Kinjo and Arakaki (2002) found that the development of this pest slowed down at high temperatures, and the development time at 35஬ was significantly greater than 30஬. At 30஬, the developmental time from egg to adult emergence in this study (19.91 days) was close to the 18.2 days reported in a Japanese population of D. indica ( Kinjo and Arakaki 2002 ), and lower than the 23.4 days re- reported in an Indian population ( Peter and David 1992 ). The temperature for shortest developmental time in this study (35஬) was greater than the Japanese population (30஬) and lower than Indian population (40஬). The variation among these temperatures may be due to the effect of host plant on developmental time of D. indica.Ravi et al. (1998) studied the effect of several species of cucurbits on the development of D. indica , and Shin et al. (2002) investigated the effect of five different host plants (cucumber, pumpkin, watermelon, oriental melon, and melon) on the biological properties of this pest, and both concluded that the host type had a significant effect on development and reproduction of this pest. Differences in the developmental time of D. indica in different regions could also be attributed to geographical race, type of host, and laboratory conditions. Sex ratio increased proportionally with increases in tem- temperature from 20 to 35஬ and was greatest at 35஬, but the increase was not significant ( Table 1 ).

Table 1.

Mean (± SE) developmental period of Diaphania indica at four different temperatures.

Different letters in rows indicate a significant difference at the 5% level according to Duncan’s multiple range test. TDL = total developmental period of larva DT = developmental time (egg to adult emergence), T = total (egg to adult death).

Effect of temperature on mortality of various developmental stages of D. indica

The temperature did not have a significant effect on the mortality of immature stages, i.e., egg, 1st instar larvae, 2nd instar larvae, 3rd instar larvae, 4th instar larvae, 5th instar larvae, prepupa, and pupa ( Table 2 ). However, adult mortality was significantly affected by different temperatures. Maximum adult mortality was recorded at 30஬ ( Table 2 ).

Table 2.

Mean (± SE) mortality of Diaphania indica at four different temperatures.

Different letters in rows indicate a significant difference at the 5% level according to Duncan’s multiple range tests.

Thermal requirements for development of D. indica

The effect of different temperatures on the developmental rate of D. indica for all stages is shown in Table 3 . The observed pupal developmental time at 35ଌ was longer than predicted by the linear relationship between developmental rate and temperature. Thus, the data for this temperature were not included when the linear regression equation was used to obtain the lower temperature threshold and thermal constant. The results are in agreement with Shimizu (2000) , who reported that the lower temperature threshold and the thermal constant of egg to adult emergence of D. indica were 12.3஬ and 357.0 DD, respectively, on artificial diet. Kinjo and Arakaki (2002) recorded the highest lower temperature threshold for pupa (14.9஬) and the lowest lower temperature threshold for larvae (12.0஬) with thermal constants of 17.24 and 82.6 DD, respectively. In that study, the lower temperature threshold and the thermal constant for development of the egg to adult emergence were determined to be 13.5ଌ and 294.1 DD, respectively. In another investigation, the thermal constant and the lower temperature threshold of egg to adult emergence were determined to be 12.05஬ and 454.55 DD, respectively ( Peter and David 1992 ). Due to large climate changes between different regions of D. indica distribution, it is likely that the local populations or strains have adapted to these conditions. In conclusion, the results of our study suggest that 35஬, which was correlated with the lowest developmental time and the highest sex ratio, is the best temperature for rearing of D. indica in the region. These results will provide insight into improving pest control.

Table 3.

The lower developmental threshold (T0) and thermal constant K (DD) of Diaphania indica at four different temperatures.

DD = degree days DT = developmental time (egg to adult emergence), T = total (egg to adult death).


Coccinellidae

Coccinellidae ( / ˌ k ɒ k s ɪ ˈ n ɛ l ɪ ˌ d iː / ) [3] is a widespread family of small beetles ranging in size from 0.8 to 18 mm (0.03 to 0.71 in). [4] The family is commonly known as ladybugs in North America and ladybirds in Britain and other parts of the English-speaking world. Entomologists prefer the names ladybird beetles or lady beetles as these insects are not classified as true bugs. [5]

The majority of coccinellid species are generally considered beneficial insects, because many species prey on herbivorous hemipterans such as aphids or scale insects, which are agricultural pests. Many coccinellids lay their eggs directly in aphid and scale insect colonies in order to ensure their larvae have an immediate food source. [6] However, some species do have unwelcome effects among these, the most prominent are of the subfamily Epilachninae (which includes the Mexican bean beetle), which are herbivorous themselves. Usually, epilachnines are only minor agricultural pests, eating the leaves of grain, potatoes, beans, and various other crops, but their numbers can increase explosively in years when their natural enemies, such as parasitoid wasps that attack their eggs, are few. In such situations, they can do major crop damage. They occur in practically all the major crop-producing regions of temperate and tropical countries.


Watch the video: 10 Beautiful Insects You can Keep as Pets (January 2022).