Effect of dietary restriction on survival, longevity and fecundity of blowfly Chrysomya chloropyga (Wied.) (Diptera: Calliphoridae)

The effect of dietary restriction (DR) on survival, longevity, ovarian development and fecundity of the blowfly Chrysomya chloropyga was examined and also included the protein content and age of the fly at first egg laying with restriction.  

Laboratory reared adult blowflies, 20 pairs each, were distributed into five cages (40 × 30 × 30 cm³) and thereafter exposed to four dietary regimes, including Continuous feeding cage (Control), 24, 48, 72 and 96 hr dietary restrictions in the insectary. The flies were fed on a mixture of ground rice and fish paste for an hour after every restriction periods. Sugar and water were provided ad libitum. Survival and longevity by the maximum number of days lived were determined. Insect weights were taken every 72 hr. Eggs laid by the control females and females exposed to 24, 48, 72 and 96 hr dietary restrictions were removed and counted to determine  the mean fecundity. Three control females and those exposed to various periods of dietary restriction were sacrificed and dissected on day 18 to determine the ovarian development. Whole body homogenate of males and females from each of the dietary restricted groups and control were prepared by homogenizing the flies with 1ml distilled water and the total protein content of the  supernatant samples were determined.

Dietary restriction shortened the life span of the adult blowfly C. chloropyga compared with flies on continuous diet. Maximum longevity of flies fed ad libitum (control) was 59 and 67 days for males and females respectively. Maximum longevity of males and females under 24 hr restriction were 44 and 45 days, and 38 and 33 for those under 96 hr restriction. Weights of males and females decreased with increase in exposure to DR and with age. There was no egg laying in the dietary restricted females and fecundity was 106.8 ± 9.12 eggs in the control females with the first egg laying occurring at day 11. The lack of egg laying was evident by the undeveloped ovaries of females exposed to 24, 48, 72 and 96 hr dietary restriction. Protein concentrations of whole body homogenate of the dietary restricted males and females were lower at ages 5, 20 and 30 days and with increase in periods of exposure when compared with flies on continuous feeding. Statistical analysis showed that dietary restriction did not significantly (p ˃ 0.05) affects the protein components of the adults. The present study concluded that dietary restriction affected some physiological activities in males and females C. chloropyga, which ultimately shortened the life span of the blowfly.