The effect of insect growth regulators and their binary mixtures on laboratory strain of spodoptera littoralis (lepidoptera: noctuidae) [electronic resource].

Includes references.

Recently, many of the conventional methods of insect control by broad spectrum synthetic chemicals have come under assault and scrutiny because of their undesirable effects on human health and the environment (Perry, et al., 1998). Furthermore, resistance has been recorded for most conventional insecticides. As a consequence, it provides impetus to study new alternatives and more ecologically acceptable methods for insect control. One of these approaches which have captured worldwide attention is the development of novel compounds capable of interfering with the processes of growth, development and metamorphosis of the target insects such as insect growth regulators (Ishaaya & Horowitz, 1997). Benzoylphenylurea (BPU's) are insecticides acting on various insect orders by reducing chitin deposition into the insect's cuticle, which in turn disrupts normal molting (Mulder & Gijswijt, 1973; Retnakaran et al., 1985). Carrol Williams coined the term 'Third Generation Pesticides' to describe hormone-based on the role of juvenile hormone. The major drawback to the use of juvenile hormone analogs (JHA's) as insecticides is that they are only active during a short period at the end of the larval instars when endogenous titer of juvenile hormone is low (Jennings, 1984). Early developed analogs such as methoprene and hydroprene have a chemical structure which resemble that of JH, modified chiefly to improve resistance to degradation in the insects. More recently, nonterpenoidal analogs such as fenoxycarb and pyriproxyfen were developed (Cusson & Palli, 2000). While success in the much earlier, it is only that insecticide came much earlier, it is only recently that insecticides which act as agonists of 20-hydroxyecdysone (20E) have been discovered (Dhadialla & Jasson 1999). These ecdysone agonists bind to the ecdysone receptor (EcR) and at molecular level through initiating and accelerating moulting process by gene regulation (Oberlander et al., 1995 and Retnakaran et al., 1995). Three compounds (Chlorfluazuron, tebufenozide and pyriproxyfen) belong to the class of IGR's insecticides. Each one has a specific mode of action was selected in this study. The present work emphasizes the effectiveness of the three IGR's interaction and their binary mixture to the 4th instar larvae of the cotton leafworm, Spodoptera littoralis.

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