Effect of Dithiocarbamate Fungicide Mancozeb on Development, Reproduction and Ultrastructure of Fat Body of Agrotis segetum Moths

Sublethal effects of ethylene bis dithiocarbamate fungicide mancozeb on development and reproduction of turnip moth (Agrotis segetum) was investigated. Larvae were exposed to the fungicide in a diet. Exposure did not cause massive mortality of larvae. However, we observed various sublethal effects. Larval development was longer than in control, also mortality of pupae and time of pupation was altered; exposure to mancozeb affected fecundity, too. Scanning electron microscopy revealed that females had laid fewer eggs, and they showed various malformations, which might affect hatching success. These changes were also in tune with observations of the larval fat body ultrastructure (transmission electron microscopy). Fat body cells showed a range of malformations: envelopes of nuclei were invaginated and swallen. In cytoplasm, glycogen content was decreased, ER showed swelling and cytoplasm became more lucent. All these changes had been observed before the mortality of larvae was noticed. Therefore, we think that ultrastructural changes may be an important marker of stress caused by mancozeb in the environment.