Sublethal Effects Of Methoxyfenozide On Common Cutworm Spodoptera Litura

The common cutworm, Spodoptera litura (Fabricius) is among the most damaging insect pest of vegetables in Asia. It is known to feed on more than 290 plant species from over 99 families worldwide. Because of its resistance to almost all kinds of chemicals against them, searching new chemicals to control the pest is a great challenge. Ecdysone agonists are one of the most recently developed groups of IGR's,which mimic the molting hormone, resulting in premature molting. Methoxyfenozide is the most recent addition to the ecdysone agonist family. It is highly specific to lepidopteran pests, but has a low toxicity towards other insect orders. In this paper, the sublethal effects of Methoxyfenozide on growth, development and fecundity of S. litura were evaluated.For the sublethal effects of Methoxyfenozide on feeding performance of 2nd intsar larva of S. litura, our data showed that there was no significant. The efficiency of conversion of digested food (ECI) in once treatment and continual treatment significantly reduced by Methoxyfenozide Relative consumption rate (RCR) was not significantly affected by Methoxyfenozide except at continual treatment LC₃₀. The efficiency of conversion of ingested food (ECI) in continual treatment at LC₁₀ was reduced compared with continual treatment at LC₃₀ and it was significantly less than the control. At LC₁₀ the 3^rd- 6^th instar duration was increased in once treatment compared with the control. Adult emergence percent at LC₁₀ was reduced to 75 %, 40 % in once treatment and continual treatment respectively compared to the control 80 %, the both values was significantly less than the control.At LC₃₀ female pupae weight values in both one treatment and continual treatment were significantly different from each others and female pupae weight was affective negatively in continual treatment compared to the control and both values were reduced when we used LC₁₀ in both treatments.When S. litura larvae were treated with sublethal concentration of Methoxyfenozide treated eggs production and their hatching rate were reduced. For the 2nd instar larvae, hatching rates were greatly reduced by Methoxyfenozide, especially, almost no eggs were hatched after LC₃₀ treatment. For total eggs laid by individual female, the egg numbers were decreased, except at once treatment with. For the tested parameters, sublethal effects of Methoxyfenozide with LC₃₀ were more significant than with LC₁₀, and that under continual treatment were more significant than that under once treatment. The results also indicated that sublethal of Chlorfluazuron and Beta-cypermethrin also reduced hatching rates of eggs and eggs numbers laid by females. For the 5th instar larvae, both total numbers of eggs and hatching rate were reduced by Methoxyfenozide treatment significantly, with the inhabiting effects which were much stronger that that for for the 5th instar larvae. When tested the sublethal effects at residue treatment, our results showed that, when treated male paired with treated female, both total eggs laid and hatching rates of eggs were negatively affected by Methoxyfenozide (LC₁₀ and LC₃₀ concentrations), while with Chlorfluazuron, total eggs were not affected at LC₁₀, and hatching rate reduced. When pupae were treated with Methoxyfenozide, egg numbers laid were not affected, while hatching rates were significantly reduced. For Chlorfluazuron and Beta-cypermethrin, total eggs did not reduced significantly, while hatching rates reduced significantly at continual treatment. In the case of only female adults were treated, total eggs and hatching rates significantly reduced by Methoxyfenozide at LC₃₀ concentration, while at the treatment of LC₁₀, When tested the sublethal effects at residue treatment, our results showed that, when treated male paired with treated female, both total eggs laid and hatching rates of eggs were negatively affected by Methoxyfenozide (LC₁₀ and LC₃₀ concentrations), while with Chlorfluazuron, total eggs were not affected at LC₁₀, and hatching rate reduced. When treated with LC₃₀, but total eggs and hatching rate reduced significantly. When the adults treated with Beta-cypermethrin, total eggs were not affected and hatching rates reduced significantly.