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Effect of precocene II - juvenile hormone inhibitor on chemoreceptor organs of Colorado potato beetle, Leptinotarsa decemlineata Say. (Col.: Chrysomelidae)статья
- Авторы: Farazmand H., Chaika S.Yu
- Сборник: Proceedings of the 9th European Symposium for Insect Taste and Olfaction (9th ESITO)
- Год издания: 2005
- Место издания: ESITO Cagliari, Italy
- Первая страница: 16
- Последняя страница: 17
- Аннотация: The Colorado potato beetle (CPB), Leptinotarsa decemlineata Say. (Col.: Chrysomelidae), is the most serious insect pest of the cultivated potato and a major pest worldwide. The increasing incidence of resistance to almost very insecticide used against it may lead to serious control problems. Precocene, a juvenile hormone inhibitor, exerts cytotoxic effects on the corpora allata of sensitive insect species, which leads to the necrosis of parenchymal cells, the source of juvenile hormone. Recently it has been observed that precocenes significantly reduce the life of the last instar larvae, induce ecdysis of larval cuticule and formation of abnormal puparia and that these effects can be reversed by juvenile hormone administration. Chemoreceptor organs of holometabola insect larvae are good models for analysing the effect biological compound, as far as the number of sensilla permanently for all larvae instars. Topical application of precocene II occurred on the dorsal part of 2nd instar larval abdomen by applying 1 μl (10 ng) solution of precocene II in acetone (1%) with a micropipette. Sensillae on the apex of the third segment and 2 basiconica, 2 trichoid and 1 conical sensillae on the distal part of the second segment. Based on the laboratory studies, with the second instar larval, which were treated 1% Precocene II, after the first molting the considerable changes of antenna cuticle structure were observed. The second and third segments of antenna in many larvae were merged, on second segment have 1-5 sensilla; on top third segment some larvae have only 2-6 sensilla. For some larvae other anomalies were observed also full reduction conical sensilla and preservation of a cuticle of the previous instar. On the maxillary palp of control larvae have 16 basiconica, 4 trichoid and 1 digitiform sensilla. All basiconica sensilla are placed on the distal apex of third segment. Results of experiments on treated larvae showed, that boundary between two terminal segments of palp often fades, and so the number of sensilla is reduced. On the labial palp of control larvae have 11 basiconica sensilla. All this sensilla are placed on the distal apex of second segment. Based on experiments, on labial palp often have remainder of cuticle of the previous instar, the number of sensilla is reduced up to 3-11, and in some cases all sensilla are reduced. Study of section through antenna and palps in treated larvae showed reduction of receptor cells and their dendrites. The structure of cuticle of sense organs differs from the control. Study of imago after emergence from pupa showed, that in some imago were observed reduction in number of sensilla only in maxillary and labial palps and were not observed change in antenna. Thus, precocene II for CPB larvae cause considerable changes in chemoreceptor organs that expressed in a reduction number of sensilla, and neurons. Most considerable changes in chemoreceptor organs in antenna, maxillary and labial palps are observed after larvae treatment on several series instars. The work was supported by RFBR (grant 04-04-48779).
- Добавил в систему: Чайка Станислав Юрьевич