Macromolecular and enzymatic abnormalities induced by a synthetic pyrethroid, Ripcord (cypermethrin), in adult beetles of a stored grain pest, Tribolium castaneum (Herbst.) (Coleoptera: Tenebrionidae)

摘要

Studies into the effects of cypermethrin (Ripcord 25EC), on adult T. castaneum were carried out. A number of enzyme activities and related macromolecules were studied after the application of cypermethrin by the residual deposit method. Almost all the enzymes and biochemical components studied were sensitive to sublethal doses of cypermethrin and these effects were dependent on the duration of treatment. All carbohydrate metabolizing enzymes (amylases, invertase [-fructofuranosidase], lactase[-galactosidase], maltase [-glucosidase] and lactate dehydrogenase) were elevated, except for trehalase, which was elevated up to day 3 but returned to normal levels. Phosphatases [phosphoric monoester hydrolases] activity increased initially but decreased with time, whereas isocitrate dehydrogenase decreased throughout the experimental period. Activity of transaminases [aminotransferases] (aspartate aminotransferase and alanine aminotransferase) decreased after cypermethrin application. Glucose content decreased during the first 3 days but increased subsequently. Fructose content showed an increase, while the glycogen content decreased throughout the study. Total lipid content was not affected after 3 days, but increased with exposure time. Cholesterol content was depleted by day 7. Total proteins decreased from day 3, while soluble proteins were not affected. DNA, RNA, and urea content increased, while uric acid showed a decreasing trend. It is concluded that sublethal doses of cypermethrin resulted in extensive enzyme induction, and utilization of carbohydrates, proteins, and lipids perhaps to produce extra energy to combat insecticidal stress.