Whitefly development

Resistance to pyriproxyfen was observed only in whitefly, and has been reported in Israel [40] and the United States [41]. The resistance to pyriproxyfen in Israel is reviewed briefly as an example. Pyriproxyfen was introduced in Israel in 1991. Although it was sprayed once a season to control whitefly (B. tahaci), the whitefly developed a middle to high resistance up to 1996. The use of pyriproxyfen was stopped in 1996 and 1997. The resistance mechanism is unknown it is reported that piperonyl butoxide, an oxidase inhibitor, does not have a synergistic effect [42]. The resistance is incompletely or partially dominant [43], and the susceptibility of whitefly was recovered by stopping the use of pyriproxyfen [44, 45]. 

Adults of this pest, Vitm (2 mm) long with white wings, fly up from plants when disturbed. Eggs laid on host plants hatch into "scales"—oval, immobile creatures found on the undersides of leaves. Both scales and adults are sap-feeders and excrete sticky honeydew, which drops onto leaves below. Sooty molds (q.v.) develop on this. A severe infestation may stunt growth. See Cabbage whitefly Greenhouse whitefly. 

The parasitic wasp Encarsia formosa is very effective against whitefly. These tiny wasps are barely visible to the eye. They lay their eggs inside developing whitefly pupa, so one of their young hatches out instead of the whitefly. For aphids, try ladybugs or Aphidoletes aphidimyza (see source on page 35 for these). 

Flufenerim [191], an insecticide that acts by inhibition of the mitochondrial electron transport of complex I, is under development by Ube Industries. Flufenerim, which is chemically related to pyrimidifen, is reported to control aphids and whiteflies. 

Despite the hick of use of PBO on food and fibre crops, evidence is accumulating for effects me dialed by PBO alone, that may have a significant role in the control of insects, particularly ones that have developed resistance to conventional insecticides. This chapter reviews such effects and summarizes research into the potential use of PBO in controlling the cotton whitefly, llemisiti rabaci. Results of this work will be published formally in due course. 

Table 25.2.5 Effects of pyriproxyfen on the development of whitefly, Trialeurodes vaporariorum.

In Japan, to control greenhouse whitefly and cotton whitefly that infest vegetables and ornamentals in the greenhouse, a yellow plastic tape formulation containing pyriproxyfen was developed. The tape has been widely used as it can lower the population of whitefly for several months after installation, and the influence on natural enemies and pollinators is low, and so forth. The action mechanism in this system is that adults attracted by the yellow color touch the tape and take pyriproxyfen into the body. The hatching of oviposited eggs is strongly inhibited by ovicidal activity via adults [38, 39]. 

Whiteflies (e.g., Bemisia tahaci) and spider mites (e.g., Tetranychus urticae) belong to the most serious sucking pests in many cropping systems. They have developed a high degree of resistance to many chemical classes of insecticides and... 

Whitefly has a unique characteristic to be attracted to yellow color. We have developed a novel pesticide delivery system utilizing whitefly attraction to yellow color and pyriproxyfen s excellent unhatching activity against whitefly. 

The last pesticide from this section is Flufenerim (Flumfen 302), which is under development by Ube Industries as an insecticide. It is reported to control aphids, whiteflies, and cotton leafworm, but has no activity against thrips [296]. Since Flufenerim is chemically related to Pyrimidifen (Miteclean 369) (Fig. 16), it was initially believed to have similar mechanism of action, i.e. inhibition of the mitochondrial electron transport of NADH dehydrogenase (NADH ubiquinone oxidoreductase, complex I) - an enzyme which transfers electrons from NADH to ubiquinone and hence opens the electron transport chain cascade. Nevertheless, it was shown that 302 reduced activity of acetylcholinesterase - an effect which possibly can be addressed to interaction with other systems [297]. 

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