What does not kill them makes them stronger: larval environment and infectious dose alter mosquito potential to transmit filarial worms

Abstract

For organisms with complex life cycles, larval environments can modify adult phenotypes. For mosquitoes and other vectors, when physiological impacts of stressors acting on larvae carry over into the adult stage they may interact with infectious dose of a vector-borne pathogen, producing a range of phenotypes for vector potential. Investigation of impacts of a common source of stress, larval crowding and intraspecific competition, on adult vector interactions with pathogens may increase our understanding of the dynamics of pathogen transmission by mosquito vectors. Using Aedes aegypti and the nematode parasite Brugia pahangi, we demonstrate dose dependency of fitness effects of B. pahangi infection on the mosquito, as well as interactions between competitive stress among larvae and infectious dose for resulting adults that affect the physiological and functional ability of mosquitoes to act as vectors. Contrary to results from studies on mosquito-arbovirus interactions, our results suggest that adults from crowded larvae may limit infection better than do adults from uncrowded controls, and that mosquitoes from high-quality larval environments are more physiologically and functionally capable vectors of B. pahangi. Our results provide another example of how the larval environment can have profound effects on vector potential of resulting adults.

Synthetic predator cues impair immune function and make the biological pesticide Bti more lethal for vector mosquitoes

“…Vector competence has two components (Breaux et al. ): physiological vector competence, dealing with physiological traits involved in the host‐pathogen interaction (e.g., immune and defense mechanisms), and functional vector competence, dealing with traits contributing to the ability of an individual mosquito to transmit the pathogen effectively given that it has attained physiological competence (e.g., flight capacity, longevity, and host localization). The net effect of larval stressors on adult vector competence will critically depend on the strength and direction both components will be affected and the resulting balance is hard to predict (Breaux et al.…”

Evidence for carry-over effects of predator exposure on pathogen transmission potential

“…Owing to predator consumption, mosquito larval densities varied over time in the experimental containers. To avoid the potential effects of changes in density on adult lifehistory traits [21,22], we standardized the larval density by randomly removing supernumerary larvae from the control containers on one occasion when larvae reached the late second instar (see electronic supplementary material). At the end of larval development, the nymphs were collected and placed in plastic cups at equal densities for emergence in 30 Â 30 Â 30 cm cages covered with a mesh and provided with water and a 5% glucose solution until experimental infection.…”

Larval nutritional stress affects vector life history traits and human malaria transmission

“…their ability to develop and transmit pathogens789101112) which are all factors influencing vectorial capacity (i.e. the potential intensity of transmission by mosquitoes, see details in ref.…”