Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 11/17/2014
Publication Date: 12/3/2014
Citation: Sisterson, M.S., Wallis, C.M., Stenger, D.C. 2014. Effects of feeding on glassy-winged sharpshooter lipid content and egg production. CDFA Pierce's Disease Research Progress Reports. p. 9.
Technical Abstract: Glassy-winged sharpshooter females emerge without mature eggs, and females must feed to produce mature eggs. As a result, allocation of incoming resources must be balanced between egg production and maintenance of other critical biological functions. Central to this process is allocation of lipids stored in the fat body. Insect eggs are comprised of 16-40% lipid, which typically originate from the fat body. Lipids from the fat body also serve as an energy source during periods of starvation and may be mobilized during periods of sustained flight. To improve understanding of basic biological factors affecting glassy-winged sharpshooter egg production, effects of feeding on glassy-winged sharpshooter lipid content and egg production were assessed. Females were field collected and given a 4 day oviposition period on sorghum to reduce variance in egg load among females. After the oviposition period on sorghum, females were divided into four groups. Females from the first group were frozen to provide an estimate of female egg load and lipid content at start of feeding assays. Females in the remaining three groups were allowed to feed on cowpea until approximately 12, 25, or 50 ml of excreta was produced. After producing the designated quantity of excreta, females were dissected to determine egg load. Mature eggs were separated from the body, and dry weights of eggs and bodies (head, thorax, and abdomen) were obtained. Lipid content of eggs and bodies were determined using a quantitative colorimetric assay. Dry weight and lipid content of glassy-winged sharpshooter bodies increased rapidly with low levels of feeding, but decelerated with additional feeding. In contrast, dry weight and quantity of lipid allocated to eggs increased slowly with low levels of feeding, but accelerated with additional feeding. Accordingly, egg production was preceded by an increase in body dry weight and body lipid content. Likewise, allocation of resources to the body decreased as resources were shifted to egg production. Collectively, the results suggest that variation in the rate of egg production among glassy-winged sharpshooter females partially may be explained by availability of lipid reserves at start of a feeding bout.