Alterations in Carbohydrate Metabolism Induced in Locusta migratoria after Poisoning with the Pyrethroid Insecticide Deltamethrin

Abstract

The effects of ethanolic solutions of deltamethrin injected at LD50 and LD75 doses on circulating and stored carbohydrates in 20- to 25-day-old male adult Locusta migratoria have been investigated. First, the impact of the use of either fed or starved locusts for this study was addressed. Starved insects appeared to be more homogeneous in relation to their hydromineral metabolism and nycthemeral cycles. Deltamethrin effects on trehalosemia showed two different phases: the first phase which took place during the first hour after the injection of deltamethrin characterized by a significant hypertrehalosemia ( + 50% for LD75). Subsequently, a second phase appeared, characterized by a significant decrease of trehalose for a period of 24 hr (−60% for LD50 and LD75 at 24 hr). Deltamethrin at the LD75 dose induced a very large decrease in fat body glycogen stores (−100% at 15 min and 6 hr after the injection of deltamethrin); then glycogen decreased in controls and virtually disappeared in treated locusts. Simultaneously, fat body glycogen phosphorylase was activated by deltamethrin at the LD75 dose. The glycogen stores of flight muscles were only slightly affected by the treatment at early times while a significant decrease was observed after 6 and 24 hr of drug action. The activity of flight muscle glycogen phosphorylase was not modified. Hemolymphatic peptide extracts from locusts previously treated with deltamethrin (LD75) show hypertrehalosemic activity.