Comparative Effects of Certain Igrs on the Carbohydrates of Hemolymph and Fat Body of the Desert Locust, Schistocerca Gregaria (Orthoptera: Acrididae)
2012
Newly molted last (5th) instar of the desert locust, Schistocerca gregaria (Forsk.), was treated through fresh plant food with 2 concentrations: high (1000.0 ppm) or low (62.5 ppm) of 3 IGRs: pyriproxyfen, tebufenozide, and lufenuron. Carbohydrate content was determined in the hemolymph and in the fat body of the early-aged, mid-aged, and late-aged 5th instar, as well as of 1- and 4-d old adult females. Pyriproxyfen prevented the nymphs to gain normal carbohydrate content in the hemolymph. In contrast, tebufenozide induced the nymphs to gain more carbohydrates. Lufenuron caused hemolymph carbohydrate content to decrease slightly in the early-aged nymphs but increased it in older nymphs. All three IGRs significantly affected the hemolymph carbohydrate content of nymphs of all ages. Pyriproxyfen drastically reduced the carbohydrate content of the hemolymph of 1-day old adults, but at the low concentration caused it to increase in the 4-day old adults. Tebufenozide induced adults to attain excess carbohydrates in the hemolymph at the low concentration level only. Lufenuron at both concentrations promoted increases of this metabolite in adults regardless of their age. Pyriproxyfen treatments of nymphs resulted in reduced carbohydrate content in the fat body of 1-d old adults, whereas tebufenozide and lufenuron at both concentrations induced increases in the carbohydrate content in fat bodies of 1- and 4-day old adults. The data from this study suggest that pyriproxyfen, tebufenozide and lufenuron alter the metabolism and storage of carbohydrate in nymphs and adults of the desert locust S. gregaria. Because carbohydrate is for all biological processes in nymphs and adults, these IGRs have considerable promise for use in the control of this destructive pest.
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