Abstract
The present study aimed to evaluate the biological effect of insect growth regulator flufenoxuron (Cascade) as a chitin synthesis inhibitor against 2nd and 4th larval instars of Spodoptera littoralis, to determine its toxicity. Effect of sublethal doses LC25, LC50 and LC90 were used to investigate the enzymatic activities. The tested IGR significantly increased the larval and pupal durations, on the other hand decrease the percentages of pupation, adult emergency, fecundity and fertility of the eggs produced by the adult progeny. The tested compound significantly induced larval mortalities, which were dose dependant. Treatments of the 2nd and 4th larval instars with the tested IGR induced some morphogenic abnormalities in larval, larval-pupal and pupal stages, as well as pupal-adult intermediate. Some emerged adults have various degrees of malformations. All the treated larvae as 2nd instar showed a high sensitivity to the tested IGRs more than 4th instars. The treated larvae in both 2nd and 4th larval instars with the sublethal doses LC25, LC50 and LC90 showed a significant decrease in enzyme activities of acid phosphatase and the non- specific esterases, α,β esterases at different times intervals post treatments.
Highlights
Bosid (Lepidoptera: Noctuidae) is a polyphagous foliage feeding insect
Estimation of enzymatic activities: Some biochemical traits of haemolymph such as acid phosphatase, α-& β- esterases were measured at different time intervals 6 -12 – 24 -48 hrs post treatment with LC25, LC50 and RESULTS Effect of flufenoxuron on some biological aspects: Effects of flufenoxuron on some biological aspects of S. littoralis treated as 2nd larval instar were recorded in Tables (1&2)
Data obtained in Table (1) showed that the corrected percentages of larval mortality had a positive relationship with the different concentrations of flufenoxuron
Summary
Bosid (Lepidoptera: Noctuidae) is a polyphagous foliage feeding insect. It considered as one of the most serious pests of many different Egyptian crops (Magd El- Din & El-Gengaihi, 2000). The first international Conference of Biological Sciences 27-29-Sep. 2010 Cairo – Egypt developmental inhibition, which inhibits or prevents normal metamorphosis of immature stages to the adult stage. These compounds have been tested successfully against several insect species (Pineda et al, 2007; Elbarky et al, 2009 and Wang &Tian 2009)
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