Mushtaq A. Saleem

Joint effects of dimilin and Ambush on enzyme activities of Tribolium castaneum larvae

Abstract Sublethal concentrations of 10 and 20 ppm (0.25 and 0.5 μM) Ambush decreased amylase activity and increased acid phosphatase (AcP) and lactate dehydrogenase (LDH) activites in sixthinstar Tribolium castaneum. Dimilin at 250 and 500 ppm (8 and 16 μM) raised activities of amylase, AcP, LDH, and alanine aminotransferase (ALAT) and depleted trehalase activity. The remaining enzymes, cholinesterase (ChE), alkaline phosphatase (AkP), asparate aminotransferase (ASAT), and isocitrate dehydrogenase (ICDH), were not affected by either insecticide. Mixtures of Dimilin and Ambush at 250 ± 10 and 500 ± 20 ppm resulted in a disturbance of almost all the enzymes tested in this study, suggesting a possible synergistic effect with reference to trehalase, ASAT, and AkP activities and an antagonistic effect with reference to amylase, AcP, LDH, ICDH, ChE, and ALAT activities. Feeding on untreated flour did not restore any of the affected enzyme activities to normal levels.

Effect of cypermethrin on the free amino acids pool in an organophosphorus-insecticide-resistant and a susceptible strain of Tribolium castaneum

Abstract 1. Proline was found to be the major component of CTC-12 (44%) and FSS II (45%) strain. 2. The cypermethrin treatment resulted in an increase in most of the amino acids of sixth instar larvae and all amino acids of adult beetles of CTC 12 strain. 3. In the susceptible strain (FSS II), however, the tyrosine, phenylalanine and arginine increased, whereas serine, proline, glycine, alanine, valine, isoleucine, leucine and lysine were decreased significantly in the sixth instar larvae. 4. In the FSS II adult beetles, only aspartic acid increased, while other amino acids either decreased (threonine, proline, glycine, alanine, valine, methionine, isoleucine, tyrososine, lysine, arginine) or remained unaffected (serine, glutamic acid, leucine, phenylalanine, histidine).

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

The effects of a synthetic pyrethroid insecticide, cypermethrin, administered as a formulation Ripcord 25EC (emulsified concentrate), to adult beetles of a stored grain pest, Tribolium castaneum, have been studied, with an objective to ascertain its toxicity on enzymes such as carbohydrases, phosphatases, dehydrogenases, aminotransferases, and concentration of various biochemical components such as monosaccharides, glycogen, cholesterol, nucleic acids, urea, total lipids, and total proteins. Almost all the enzymes and biochemical components were sensitive to sublethal doses of Ripcord 25 EC and these effects were found to be dependent on the duration of treatment. All carbohydrate metabolizing enzymes (amylase, invertase, lactase, maltase, lactate dehydrogenase) were elevated, except for trehalase, which was also elevated up to day 3 but returned to normal levels subsequently. Phosphatases (alkaline as well as acidic) were increased first and decreased thereafter, while isocitrate dehydrogenase decreased throughout the experimental period. Transaminases (aspartate aminotransferase and alanine aminotransferase) showed a decreasing trend. Of the other biochemical components tested, 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 disturbed up to day 3 but increased thereafter. Cholesterol content was depleted by day 7. Total proteins started decreasing from day 3 onwards, while soluble proteins were not affected. DNA, RNA, and urea contents exhibited elevated levels, while uric acid showed a decreasing trend. Sublethal doses of Ripcord, therefore, resulted in extensive enzyme induction, and utilization of carbohydrates, proteins, and lipids, in the given order, perhaps to produce extra energy to combat insecticidal stress. Arch. Insect Biochem. Physiol. 39:144‐154, 1998.