COMPARATIVE BIOLOGICAL AND BIOCHEMICAL ASSESSMENT FOR TOXICOLOGICAL PROFILE OF SOME ECO-FRIENDLY INSECTICIDES APPLIED FOR CONTROLLING OF THE FOURTH INSTAR LARVAE OF SPODOPTERA FRUGIPERDA

Document Type : Original Research Papers

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Zoology Department, Faculty of Science, South Valley University, Qena, Egypt

Abstract

The fall armyworm (Spodoptera frugiperda) constitutes an urgent threat to maize cultivation in Egypt. This study aimed to assess the effectiveness of three insecticides lufenuron (5% emulsifaible concentrates) as an insect growth regulator, emamectin benzoate (5% soluble granules) and "Bacillus thuringiensis subspecies Kurstaki (Btk, 6.4% wettable powder) as bioinsecticides, against fourth instar larvae of S. frugiperda, within controlled laboratory conditions. The larvae extracted from maize fields in Upper Egypt, Qena Governorate, and subsequently reared under laboratory conditions. Through toxicity assays, dose-dependent mortality rates were observed for all three insecticides, with emamectin benzoate displaying the highest toxicity (LC50: 0.0079 ppm), followed by Btk (LC50: 1.6857 ppm), and lufenuron (LC50: 3.2155 ppm). The variance in efficacy attributed to varying in chemical compositions and modes of action. Furthermore, the impact of these insecticides on larval development was investigated. Emamectin benzoate led to elongated larval development, lufenuron and Btk induced prolonged larval development and postponed pupation. Substantially, Btk significantly altered carbohydrate level; however, both Btk emamectin benzoate reduced significantly total protein. Moreover, disparity with significance in the activity of the digestive enzymes activity of amylase and invertase, likewise detoxifying enzymes notably glutathione S-transferase (GST) and acetylcholinesterase (AChE) was apparent. The investigation ensures the important extent of selecting insecticides and potential consequences of lufenuron, emamectin benzoate and Btk considering their distinct effects for efficient fall armyworm management. The further studies are recommended to illuminate ecological consequences and enhance the pragmatic utilization of these insecticides under world knowledge.

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