Whiteflies

Their distribution,biology,damage and control measures

1. Muzamil Syed Shah Section Entomology 16-ZYM-24 GH-7892 Whiteflies Diversity, distribution, economic importance and their management

2. White appearance of adults due to deposition of wax on the body and wings. Collected from Agriculture department AMU, Aligarh WHY THEY ARE CALLED WHITEFLIES ?

3. Phylum: Arthropoda Class: Insecta Order: Hemiptera Superfamily: Aleyrodoidea Family: Aleyrodidae Subfamilies Aleurodicinae Aleyrodinae TAXONOMIC POSITION

4. Small insects. M ost species with a wingspan of less than 3 mm and a body length of 1 mm to 2mm . Adults have well-developed antennae, which in most species in this family are seven-segmented. INTRODUCTION

5. There are two ocelli , which generally in the Aleyrodidae are placed at the anterior margins of the compound eyes . Both sexes have functional mouthparts and two pairs of membranous, functional wings. The wing venation is reduced. Cont …….

6. The digestive system of the Aleyrodidae is typical of the Sternorrhyncha , including a filter chamber , P roduce large quantities of honeydew ; T he honeydew emerges from the anus, which is inside an opening called the vasiform orifice on the dorsal surface of the caudal segment of the abdomen. This orifice is large and is covered by an operculum.

7. The adult female lays eggs which are provided with a stalk or pedicel at one end with which they are attached to the leaf . The first instar is called crawler . The legs and antennae of the second, third, and fourth nymphal instars are atrophied and these instars are sessile . The adult develop within the quiescent fourth instars . LIFE CYCLE

8. There are currently around 1550 known species of whiteflies under two subfamilies, namely., Aleyrodinae . Aleurodicinae . Indian fauna of whiteflies comprises 290 species in 57 genera. SPECIES DIVERSITY OF WHITEFLIES

9. Most noxious insects attacking field crops, green house crops and plants and trees. Loss is due to their activities of sucking the plant sap, acting as vectors of viral diseases. ECONOMIC IMPORTANCE

10. The pest is more important as a transmitter of viruses such as., Sweetpotato mild mottle virus, Sweet potato yellow dwarf disease , Sweetpotato leaf curl, and Particularly sweetpotato chlorotic stunt virus, a key component of sweetpotato virus disease.

11. Production of honey dew leading to the development of mould on leaves. Adversely affecting photosynthesis.

12. Aleurocanthus woglumi , citrus blackfly, which, in spite of its color, is a whitefly that attacks citrus Aleyrodes proletella , cabbage whitefly, is a pest of various Brassica crops. Bemisia tabaci , silverleaf whitefly, is a pest of many agricultural and ornamental crops. Trialeurodes vaporariorum , greenhouse whitefly, a major pest of greenhouse fruit, vegetables, and ornamentals. ECONOMICALLY IMPORTANT WHITEFLIES

13. Whiteflies feed by tapping into the phloem of plants, introducing toxic saliva and decreasing the plants' overall turgor pressure . Since whiteflies congregate in large numbers, susceptible plants can be quickly overwhelmed. Further harm is done by mold growth encouraged by the honeydew whiteflies secrete . DAMAGE

14. Whitefly control is difficult and complex, as whiteflies rapidly develop resistance to chemical pesticides. CONTROL

15. Pesticides used for whitefly control usually contain Neonicotinoid compounds as active ingredients: Clothianidin Dinotefuran Imidacloprid Thiamethoxam

16. Several predators and parasitoids may be effective in controlling whitefly infestations, including green lacewings , ladybirds , minute pirate bugs , big-eyed bugs, damsel bugs, and phytoseiid mites. Pirate bug feeding on whitefly larvae NON-CHEMICAL MEANS

17. A number of plants can be intercropped with vegetables, in a garden setting, serving as companion plants to protect against whiteflies. EXAMPLES Nasturtiums are thought to provide a defense to tomatoes . COLLATERAL HOST PLANTS

18. Zinnias , attract predators that consume whiteflies, including hummingbirds and predatory wasps and flies .

19. REFERENCES R.Sundararaj Institution of Wood Science & Technology Martin , J.H.; Mound, L.A. (2007). "An annotated check list of the world's whiteflies ( Insecta : Hemiptera : Aleyrodidae )". Zootaxa . 1492 : 1–84. Richards , O. W.; Davies, R.G. (1977). Imms ' General Textbook of Entomology: Volume 1: Structure, Physiology and Development Volume 2: Classification and Biology. Berlin: Springer. ISBN   0-412-61390-5 . Retrieved 2016 07 02, from the Integrated Taxonomic Information System on-line database, http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=200525 Martin , Jon H. Giant whiteflies ( Sternorrhyncha , Aleyrodidae ). Tijdschrift voor Entomologie 150: 13–29, Figs. 1–33, Table 1. [ISSN 0040-7496]. http://www.nev.nl/tve 2007 Nederlandse Entomologische Vereniging . Published 1 June 2007. [1]

20. THANK YOU

21. REFERENCES

22. Both immature and adult whiteflies feed by piercing the undersurface of leaves and sucking the plant sap. The nymphs, which feed in one position for 2-4 weeks, may cause yellow spots which are conspicuous on the upper leaf surface. On older leaves the spots develop a brown centre . Some sweetpotato cultivars respond to the damage by producing purple pigments, resulting in purple spots with a brown centre . Feeding by adults usually causes no visible lesion, but high whitefly populations may cause yellowing of infested leaves, and may stunt plant growth. Whiteflies produce honeydew, a sugary secretion, making the leaf surface sticky. In humid conditions, sooty mould may develop on the leaf surface, reducing its capacity to trap light required for the plant's normal growth. The pest is more important as a transmitter of viruses such as sweetpotato mild mottle virus, sweetpotato yellow dwarf disease, sweetpotato leaf curl, and particularly sweetpotato chlorotic stunt virus, a key component of sweetpotato virus disease.

23. Egg. Small, elliptical, smooth surfaced, yellow to tan eggs are laid on leaf surface, usually on undersurface, in irregular, waxy lines, forming a spiral ( hence the common name). Eggs take about seven days to hatch. Larva. There are four larval stages that take about 30 days to complete. The first instar is mobile, crawling a short distance from the egg before settling to feed. The following 3 instars are immobile, appearing as a small, flattened, oval scale on the leaf surface. The final instar stops feeding and is referred to as the Pupa. It is colourless or yellowish, nearly oval, flat and about 1 mm long and 0.75 mm wide. They secrete waxy threads on their back which are about 12-15 mm long and provide a protective cover. Adult. The adults are white and quite small, about 2-3 mm in length and coated with a fine dust-like waxy secretion. The eyes are dark reddish-brown, wings are transparent with white powder covering. Females lay eggs throughout their lifetime

24. Biology and ecology Whiteflies have six life stages - the egg, four nymphal stages, and the adult. The development time of this insect from egg to adult depends upon temperature. Temperature range of 10 to 32oC favours development. Low temperatures increase egg mortality. The pest is more common during the dry season. The female may lay 100 or more eggs on the back or undersurface of the leaves. They hatch after about seven days. The first instar nymphs emerge and feed. After the first moult they become fixed to one place of the leaf and develop into pale green or creamy flattened scale-like bodies. The third moult gives rise to the “ puparium ” which is less flat than the previous nymphal stages and the red eyes of the adult can be seen through the integument. Development of one generation takes 2 to 4 weeks depending on temperature. In both species, reproduction can occur without mating (parthenogenesis). Unmated females produce only male progeny.

25. Biological control Natural enemies were introduced to control whiteflies. The parasitic wasp Encarsia formosa is an effective biological control agent against both A. dispersus and B. tabaci while some species of coccinellid beetles, true bugs ( Hemiptera : especially Anthocoridae and predatory Miridae ), lacewings ( Neuroptera : Chrysopidae , Hemerobiidae , Coniopterygidae ), flies ( Diptera : Dolichopodidae , Syrphidae , Anthomyoodae ), ants (Hymenoptera: Formicidae ), spiders ( Araneida ) and mites ( Acarina : Phytoseiidae , Stigmaeidae ) also prey on them.

26. Several Aphelinid parasitoids in the genera Encarsia and Eretmocerus , attack the pest and often control it. Their overall effect (especially in the field) may sometimes be limited due to the rapid development of the pest which often overtakes that of its enemies. Then, the fact that even a few whiteflies can transmit pernicious plant viruses, a situation that requires a pest-free crop environment, which in turn promotes the use of pesticides. Finally, chemicals that are applied against other major cotton and tomato pests usually kill the enemies. Some entomophatogenic fungi infect B. tabaci , but their overall effect in the field or in greenhouse is not known.

27. Aleurocanthus Aeurolobus Aleuromarginatus Aleuroplatus Orientaleyrodes Hindaleyroes Dialeurolonga Cockerellilla Some important genera…