Differences Of Development And Nutritional Accumulation Between Pre-oviposition And Diapause Preparatory Period In The Cabbage Beetle, Colaphellus Bowringi

Insects in diapause characteristically feed very little or not at all so that they are largely or totally dependent on energy reserves prior to the entry into diapause. Thus, the preparation phase before diapause is very essential for diapause individuals. Diapause is programmed by environmental cues well before the onset of arrest, and diapause-destined insects often alter their physiology during the diapause preparatory period. The accumulations of more nutrient reserves are among the most conspicuous alterations that occur during the pre-diapause period. However, due to the limitations of the research object, there is a lack of the studies about dynamic of nutrient reserves during the diapause preparation period before; further studies are needed to make sure the differences of the nutrient reserves between diapause-destined and nondiapause-destined individuals. These studies will contribute to a better understanding of the molecular regulation mechanism of diapause preparatory.The cabbage beetle Colaphellus bowringi is a serious pest of crucifers which has facultative reproductive diapause. Diapause preparatory phase is short and clear. The4feeding days after adults eclosion that were reared at25℃combined with LD12:12and LD16:8is diapause preparatory period and pre-oviposition period. In this paper, cabbage beetles are used as the materials in these experiments, and the study focuses on the changes of form in ovaries, body fat, lipid droplet and mitochondria, and the metarblic reserve changes in female, ovaries, fat body and hemolymph during pre-oviposition period and diapause preparatory period. The main results are as follows:1. Differences of development in ovaries and fat body during pre-oviposition period and diapause preparatory period in the C.bowringiNo significant change in morphology of ovaries and fat body is observed in the cabbage beetle without feeding during pre-oviposition period and diapause preparatory period. In3feeding days after adults eclosion, there are much more yolk deposition in the ovaries and mitochondria in the nondiapause-destined individuals, but increased fat body significantly in the diapause-destined individuals, meanwhile, the body fat dry weight was significantly increased with more lipids droplet than female during pre-oviposition period. The data suggest significant differences of the dynamic changes of the nutrient reserves during the pre-oviposition period and diapause preparatory period in the C. bowringi.2. Changes in nutrient reserves during pre-oviposition period and diapause preparatory period in the C.bowringiIn3feeding days after adults eclosion, the fresh weight and the water content of C.bowringi during the pre-oviposition period was significantly increased compared with those during diapause preparatory period, but there is no significant difference between the dry masses of female adults of the two periods. The nondiapause-destined individuals accumulate greater proteins while the diapause-destined individuals accumulate greater triacylglycerol (TAG). In terms of metabolic synthetic substances, significant differentiation between nondiapause-destined and diapause-destined individuals is shown in2feeding days after adults eclosion. The proteins accumulate mainly in the ovaries during the pre-oviposition period and TAG in the fat body.The study showed the differences of the dynamic changes of the nutrient reserves during the pre-oviposition period and diapause preparatory period, and the result also helps us to have a better understanding about the key point and time of the changes. The result can provide basic information for the research of identify the candidate diapause-associated genes and molecular regulation mechanism of diapause in the C.bowringi.