Disruptive Effects of Some Novel Chitin Synthesis Inhibitors on the Transaminase Activity in Larval Tissues of Spodoptera littoralis (Lepidoptera: Noctuidae)

Objective of the present study was to investigate the effects of novel CSIs, viz., Novaluron, Cyromazine, and Diofenolan, on the activities of glutamic oxaloacetic (GOT) and glutamc pyruvic (GPT) transaminases in larval haemolymph and fat bodies of the economically dangerous insect, Spodoptera littoralis. LC 50 of each CSI (2.71, 74.44 and 7.65 ppm, respectively) was applied on the penultimate instar larvae and the enzyme activities were determined in the successfully moulted last instar larvae of different ages. Cyromazine and Diofenolan exhibited a prevalent enhancing effect on GOT activity in haemolymph of larvae of all ages. Novaluron exhibited a similar inducing effect on the enzyme activity except in 4-day old larvae. With regard to fat bodies, remarkably decreasing GOT activity was determined in larvae of all ages, regardless the CSI. Regarding GPT activity, CSIs exhibited contradictory effects in haemolymph of larvae since Novaluron elaborately promoted it, with an exceptional case of 6-day old larvae while Cyromazine and Diofenolan treatments resulted in conspicuously declined enzyme level, with few exceptions. Dealing with fat bodies, Cyromazine and Diofenolan enhanced the enzyme activity while Novaluron failed to exhibit an effect, irrespective of the larval age.