© 2019 JETIR January 2019, Volume 6, Issue 1 www.jetir.org (ISSN-2349-5162) Morphology and Adaptation of Immature Stages of Hemipteran Insects Devina Seram and Yendrembam K Devi Assistant Professor, School of Agriculture, Lovely Professional University, Phagwara, Punjab Introduction Insect Adaptations An adaptation is an environmental change so an insect can better fit in and have a better chance of living. Insects are modified in many ways according to their environment. Insects can have adapted legs, mouthparts, body shapes, etc. which makes them easier to survive in the environment that they live in and these adaptations also help them get away from predators and other natural enemies. Here are some adaptations in the immature stages of important families of Hemiptera. Hemiptera are hemimetabolous exopterygotes with only egg and nymphal immature stages and are divided into two sub-orders, homoptera and heteroptera. The immature stages of homopteran families include Delphacidae, Fulgoridae, Cercopidae, Cicadidae, Membracidae, Cicadellidae, Psyllidae, Aleyrodidae, Aphididae, Phylloxeridae, Coccidae, Pseudococcidae, Diaspididae and heteropteran families Notonectidae, Corixidae, Belastomatidae, Nepidae, Hydrometridae, Gerridae, Veliidae, Cimicidae, Reduviidae, Pentatomidae, Lygaeidae, Coreidae, Tingitidae, Miridae will be discussed. Homopteran families 1. Delphacidae – Eg. plant hoppers They comprise the largest family of plant hoppers and are characterized by the presence of large, flattened spurs at the apex of their hind tibiae. Eggs are deposited inside plant tissues, elliptical in shape, colourless to whitish. Nymphs are similar in appearance to adults except for size, colour, under- developed wing pads and genitalia. 2. Fulgoridae – Eg. lantern bugs They can be recognized with their antennae inserted on the sides & beneath the eyes. Some species are tropical types and are luminous, which secrete large quantities of wax. Eg. wax-tail hopper JETIRDW06155 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 969 © 2019 JETIR January 2019, Volume 6, Issue 1 www.jetir.org (ISSN-2349-5162) (Pterodictya reticularis). Eggs are laid on tree surface and covered with waxy substances thus resembling like egg case. Nymphs often form long filaments presumably for protection against predators. 3. Cercopidae – Eg. spittle bugs Eggs are laid in mass on leaves surface, rounded in shape. Nymphs cover themselves on 7th & 8th abdominal segments with frothy mass which is a foam made of fluid voided from anus & from a mucilaginous material secreted by epidermal glands. Through caudal appendages, the air bubbles are inserted into the foam. Only nymphs are capable of producing foam for protection against other organisms and to avoid dessication. Adults do not produce foam. 4. Cicadidae – Eg. cicadas Eggs are inserted into grasses, shrubs, living or dead twigs of trees, which are elongated in shape, colourless to whitish in appearance. Nymphs can be recognized with massive & enlarged pincher-like forelegs adapted for digging and grasping. They hatch from the eggs in a month & are dropped to the ground, the last nymphal instar climbs up on tree where the final moult takes place. The 17-year cicada, Magicicada septendecim (L.) spends almost 17 years of its life cycle in its nymphal stage. 5. Membracidae – Eg. tree hoppers Eggs are laid individually or in groups either placed into living tissue of plant or deposited on surface, overwinter & hatch in spring. Nymphs are dropped to vegetation where they complete their development. The dorsal sides of thorax in nymphs are covered with tubercles or spines and can be differentiated from the adults by the absence of pronotal structure, but sometimes formed filaments or spinose projections on tergites. 6. Cicadellidae – Eg. leaf hoppers Eggs may either remain dormant for a month to almost a year or develop and hatch within few weeks. They undergo a series of 5 moults and reach its adult stage. Some special adaptations in nymphs are presence of jumping hind legs with the hind tibiae having two or more rows of spines, which are capable of powerful leaps adapted for search of food & avoiding predators; large eyes for excellent visual and also acts as avoidance from detection or capture by potential predators. Nymphs are also capable of detecting reflectance spectrum of several colors, with hues of yellow being most attractive. Several species (e.g. Glassy-winged sharpshooter - Homalodisca vitripennis) have the ability to produce white JETIRDW06155 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 970 © 2019 JETIR January 2019, Volume 6, Issue 1 www.jetir.org (ISSN-2349-5162) chalky material known as brochosomes placed on wings. After the eggs have been deposited into plant surfaces, females then scrape this material to "powder" the area and cover the eggs for protection and the process is known as "powdering”. 7. Psyllidae – Eg. psyllids Psyllids are different from other hemipterans since they are not phloem specialists (feed on xylem and mesophyll) and therefore they have rudimentary filter chamber and only four Malphigian tubules. Eggs are pedunculate or stalked and are placed on exposed surfaces of leaves which enables them to draw water from host plants. The hind legs of nymphs are fitted for leaping and ability to jump high as in jumping plant lice. Many species produce large quantities of white waxy secretions which resemble woolly aphids. Nymphs are smooth, possess large wing pads and sometimes have small abdominal fringes. There are 5 nymphal instars and some species' nymphs live under sugar covers called "lerps," while others are gall-enclosed or free-living. Lerps are protection cover formed from sugar and wax excreted by insects which hardens in contact with air. These lerps vary in size, colour and shape viz. cones, univalves, bivalves or fan & white to dark brown. 8. Aleyrodidae – Eg. whiteflies Eggs are pedunculate, connected by a short stalk & deposited in a circle or crescent on the underside of the leaves. There are 4 larval instars and only the 1st instar is with well-developed legs called “crawler” and the subsequent instars are sessile. Wings develop internally during metamorphosis. They differ from other families in the presence of an extra form i.e. the 4th instar forms a "pupal case” or "puparium" which resembles like the pupa of other holometabolous insects. The nymphs are often mistaken for soft scales. Thus, they can be differentiated by the presence of vasiform orifice, operculum & ligula. Sometimes, nymphs and pupae of some species are covered with various types of wax while others are devoid of wax. 9. Aphididae – Eg. aphids The most common reproductive strategy in this family is viviparous parthenogenesis alternating with sexual reproduction (holocyclic). Some of the spp. (esp. crop pest) prevails in warm climate with anholocyclic life lacking sexual reproduction. In typical life cycle, fundatrix ♀ hatches from the overwintering eggs. Female fundatrices are those which are viviparous, parthenogenic, often without wings (apterous) and in turn produce more viviparous and parthenogenic ♀, both with wings (alate) & JETIRDW06155 Journal of Emerging Technologies and Innovative Research (JETIR) www.jetir.org 971 © 2019 JETIR January 2019, Volume 6, Issue 1 www.jetir.org (ISSN-2349-5162) without wings (apterous) and most of the aphid species reproduces without an egg stage. The adaptations for defense against natural enemies in aphids include secretion of defensive wax fluid (triacylglycerols) from cornicles. In some species of aphids, whole body is often covered with white waxy fibers secreted by dermal gland; excretion of honeydew from anus which is produced in sufficient quantity to cause stickiness on surface to ward off natural enemies. A structural adaptation in myrmecophilous aphids (aphid species being predated by ants) is the presence of group of setae in anal region to hold honeydew droplet while the attending ant imbibes it. 10. Phylloxeridae – Eg. phylloxera Phylloxerids resemble like aphids. These insects overwinter duirng their egg stage. In early spring, nymph hatches and migrates to developing leaf to feed thus causes irritation in plant tissues ultimately forming galls. When they are matured, ♀ produces numerous parthenogenetic young ones which will migrate to other host plants to form new galls. Some nymphs can fall to the ground after a few generations and burrow into the roots for feeding. The winged adults will emerge from the ground in mid-summer and lay eggs on vines where they develop into nymphs and adults. Single egg lay again on the vine after mating, thereby completing its life cycle. 11. Pseudococcidae – Eg. mealy bugs Some spp. are oviparous (egg laying) and others viviparous (give birth to young ones). Oviposition take place in a loose, cottony wax called as ovisac. The first instar nymphs are very active and mobile called ‘crawlers’. After the 1st moult, they lose their legs & antennae and become sessile during subsequent moults. ♀ excrete large amount of honeydew. In arid regions, excreted honeydew solidifies on the leaves and accumulates in thick layer forming a sweet, sugar-like material called “Manna”. They survive and over-winter during cold conditions as eggs in ovisac or other stages. During warm climates, mealy bugs remain active and reproduce throughout the year increasing its populations. 12. Coccidae – Eg. soft scales Coccids either lay oval shaped eggs under scale or produce live young