Inhibited reproductive capacity of Egyptian cotton leaf worm Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) by the chitin synthesis inhibitor Novaluron.

Ghoneim K,Hamadah Kh,Basiouny A,Waheeb H,Tanani M

doi:10.21608/eajbsa.2014.13144

Ghoneim K, Hamadah Kh + Show 3 more

Open Access

https://doi.org/10.21608/eajbsa.2014.13144

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Abstract

For evaluating the effects of Novaluron on various parameters of the reproductive capacity of Spodoptera littoralis, a concentration range of 1.000.0001ppm was applied on the newly moulted penultimate (5 th ) instar larvae and a concentration range of 0.10-0.0001ppm was applied on the newly moulted last instar larvae. A predominant inhibitory effect of Novaluron was exhibited on the oviposition efficiency since the oviposition rate was seriously regressed in no certain trend, regardless the time of larval treatment and concentration level. Treatment of penultimate or last instar larvae with Novaluron resulted in drastically reduced fecundity in a dose-dependent course. A reducing action of Novaluron was exerted also on fertility after treatment of larvae with different concentration levels, regardless the time of treatment. After treatment of penultimate or last instar larvae with Novaluron, the embryonic development had been generally subjected to a retarding effect since the incubation period was pronouncedly prolonged, regardless the concentration level.

Highlights

Over the last few decades, the intensive use of broad-spectrum insecticides against the Egyptian cotton leaf worm, Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae) has led the development of resistance to many registered pesticides making their control even more difficult (Smagghe et al.,1999; Miles and Lysandrou, 2002; Aydin and Gurkan, 2006)
Depending on the mode of action, insect growth regulators (IGRs) had been recently grouped in chitin synthesis inhibitors (CSIs) and substances that interfere with the action of insect hormones (Tunaz and Uygun, 2004)
Data assorted in Table (1) clearly show a predominant inhibitory effect of Novaluron on the oviposition efficiency since the oviposition rate was seriously regressed, regardless the concentration level applied on penultimate instar larvae

Summary

Introduction

Over the last few decades, the intensive use of broad-spectrum insecticides against the Egyptian cotton leaf worm, Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae) has led the development of resistance to many registered pesticides making their control even more difficult (Smagghe et al.,1999; Miles and Lysandrou, 2002; Aydin and Gurkan, 2006). Owing to its socioeconomic importance, the insect is subject to extensive research, much of which is envisioned to finding new ways to control it as a pest and to improve the effects of known pest control methods (Hussain, 2012). At present, using insect growth regulators (IGRs) is considered as the possible alternative way of conventional synthetic insecticides for controlling this pest (Raslan, 2002). They have novel modes of action which disrupt the physiology and development of the target pest. Such compounds tend to be selective and generally less toxic to non-target organisms than conventional insecticides (Gurr et al, 1999). Depending on the mode of action, IGRs had been recently grouped in chitin synthesis inhibitors (CSIs) and substances that interfere with the action of insect hormones (i.e. juvenile hormone analogues, and ecdysteroids) (Tunaz and Uygun, 2004)

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