Abstract
The present research focuses on the effect of teflubenzuron on the 4th larval instar of the cotton leafworm, Spodoptera littoralis under laboratory conditions. Teflubenzuron exhibited larvicidal activity (LC50 8.45 ppm) after 72 hours of treatment. Scanning electron microscopy (SEM) showed growth disruption and abnormalities in the external morphological features of cuticle and head capsule in larvae treated with teflubenzuron. Marked biochemical changes in chitin synthesis pathway were recorded. Protease enzyme activity was significantly reduced, whereas the activities of both chitinase and phenoloxidase were significantly elevated in treated larvae in comparison to controls.
Highlights
Insect growth regulators (IGRs) represent the third generation insecticides which are effective as components in integrated pest management (IPM) programs for insect control
Ultrastructure studies: Different morphological features of molting failure were observed in 4th instar larvae treated with sublethal concentration (LC50) of teflubenzuron using light and scanning electron microscope as illustrated in Figures (1-3)
Normal larvae with successfully molting were recorded in (Figs. 1a & b), while the signs of failure molting leading to mortality were included: Larvae became inactive, appeared to be wet and the molting fluid oozing out the head capsules
Summary
Insect growth regulators (IGRs) represent the third generation insecticides (or biorational insecticides) which are effective as components in integrated pest management (IPM) programs for insect control. IGRs generally control insects by being juvenile hormone agonists, ecdysone agonists, ecdysone antagonists and chitin synthesis inhibitors (CSIs) (Pfeiffer 2007). Two types of CSIs have been developed and used as commercial agricultural pests, benzoylphenyl ureas (BPUs) and buprofezin (Palli and Retnakaran 1999; IRAC 2017). Teflubenzuron is a BPU, (commercial trademark Nomolt). Bažok et al, (2009) reported that teflubenzuron might provide moderate to sufficient level of control in an IPM program against the European corn borer, Ostrinia nubilalis. The effects of different substituents on the benzene rings in BPUs were analyzed for larvicidal activity against Spodoptera littoralis (Nakagawa et al, 1989)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
