Effect of larval nutritional regimes on morphometry and vectorial capacity of Aedes aegypti for Dengue transmission

Abstract

BACKGROUND: Nutritional level in larval diet of mosquito vectors influence on life history traits and vectorial capacity (VC). Therefore, the present study was carried out to assess the effect of larval diet concentration on vector bionomic and VC of Aedes aegypti in Sri Lanka. Method. Three batches of 400 Ae. aegypti larvae (first instar) were reared under different concentrations of larval diet (6%, 8%, and 10%; Volume/Volume), which was prepared by mixing 12.5 g of tuna meal, 9.0 g of bovine liver powder, and 3.5 g of Brewer’s yeast, in 100 ml of distilled water. The effect of larval diet concentration on different morphometric and functional parameters of larvae (length and width of head, abdomen, survival rate, and pupation success), pupae (length and width of cephalothorax, survival rate, and adult emersion), adult (length and width of thorax, abdomen, survival rate, longevity, biting frequency and fecundity of adults) were examined. In addition, VC of Ae. aegypti was evaluated. The General Linear Model (GLM) was used for the statistical analysis. Results. Larval head length, head width, thoracic width, abdominal length, abdominal width, total length, and survival rate significantly increased with higher doses of larval diet (P<0.05). In case of pupae, length, and width of cephalothorax, survival rate and adult emergence rate denoted an increasing trend with the elevated larval diets. However, the variations of survival rate and adult emergence rate were statistically significant (P<0.05). In adults, all morphometric parameters (thoracic length, abdominal length, abdominal width, and wing length) significantly increased with elevating larval diets levels (except for thoracic width) along with the biting frequency, fecundity, and survival rate (P<0.05) of adult females. The VC also denoted significant variations (F4,14 = 24.048; ) with the larval diet concentration, whereby the highest VC of 196.37 was observed at 10% treatment. Conclusion. Larval food availability has a significant influence on the adult fitness and thus may affect the incidence of dengue due to variations in the VC of Ae. aegypti. Hence, this investigation highlights the requirement in accounting the environmental variation at the larval stages in order to understand transmission dynamics and control of dengue in Sri Lanka.