Toxicity and kinetics of methoxyfenozide in greenhouse‐selected Spodoptera exigua (Lepidoptera: Noctuidae)

Abstract

Methoxyfenozide (RH-2485) was found to be 7.5-fold less toxic in terms of LD50 values against last-instar larvae of a greenhouse-selected strain of the beet armyworm Spodoptera exigua (Hübner) that was collected in July 2001 in an experimental greenhouse for resistance at Murcia in southern Spain, in comparison with a laboratory susceptible strain. To date, the compound is the newest member of this new group of moulting hormone accelerating IGRs to reach the marketplace against Lepidoptera. To understand this different potency in the greenhouse-selected S exigua, oxidative metabolism and acetylcholinesterase activities were measured in last-instar larvae and adults. In addition, we determined, by the use of 14C-labelled methoxyfenozide, the pattern of absorption in body tissues and excretion via faeces in last-instar larvae of the greenhouse-selected strain and compared the results with those from the laboratory susceptible strain. It was striking that the rate of excretion was about twice as high in the greenhouse-selected strain, resulting in a more rapid clearance of insecticide amounts from the insect body. Data are discussed in relation to mechanisms of lower toxicities for this new group of IGRs.

Emamectin benzoate: Potential larvicide and antifeedant agent against cotton Boll worm Helicoverpa armigera (Lepidoptera: Noctuidae)

“…Moreover, the tendency of insecticides to accumulate in lipids has increased the human health risks by their amplification in aquatic food chains (Schlechtriem et al, 2012). To alleviate the problem developed due to the overdependence on conventional insecticides in pest control programs, various groups of insecticides of natural origin have been synthesized with specific and selective action against desired species; and found to be safer for natural enemies and environment (Dhadialla et al, 1998;Thompson et al, 2000;Ignacimuthu and Jayaraj, 2003;Smagghe et al, 2003). Among various bio-insecticides dominant in Indian market field with different modes of action, Emamectin benzoate, a second generation Avermectin, composed of abamectin extracted from Streptomyces avermitilis a soil microorganism, has been found to possess significant efficacy against pests (Burg et al, 1979, Birah et al, 2008Temple et al, 2009).…”

Sublethal Effects of Spinosad (Tracer®) on the Cotton Leafworm (Lepidoptera: Noctuidae)

“…Over the past 25 years, the intensive use of broad-spectrum insecticides against S. littoralis has led the development of insect resistance to many registered pesticides (Aydin and Gurkan 2006). In this scenario, using new types of insecticides, originated from natural agents or products that disrupt the physiological processes of the target pest, could be useful alternatives in the integrated management approach (Dhadialla et al 1998; Thompson et al 2000;Smagghe et al 2003). Spinosad is one of these biologically derived insecticides.…”

Field evaluation of methoxyfenozide 24 SC against leaf miner, Aproaerema modicella (Deventer) and its effect on predatory coccinellids of groundnut

“…Smagghe et al (2003) who reported that methoxyfenozide is highly specific to lepidopteran pests, but has a low toxicity towards other insect orders. Sun et al (2000) also reported the efficacy of methoxyfenozide against leaf roller.…”