Can Pesticides and Larval Competition Alter Susceptibility of Aedes Mosquitoes (Diptera: Culicidae) to Arbovirus Infection?

Abstract

Density-dependent processes such as larval competition may be important regulatory factors among some mosquito species. The application of pesticides used for control may alter these density-dependent interactions with consequences for the number of survivors and associated sublethal and chronic effects on these individuals. We examined how intraspecific competition among larvae and low concentrations of malathion alter Aedes aegypti L. and Aedes albopictus Skuse adult life history traits and competence for arboviruses using Sindbis virus as a model system. Larvae were reared at densities of 150 and 300 larvae per container and in the absence or presence of 0.04 parts per million of malathion, before surviving females were exposed to an infectious blood meal containing 10(5) plaque-forming units/ml Sindbis virus. For both species, competition and the presence of malathion reduced survival to adulthood. The presence of malathion eliminated the negative effects of competition that resulted in lengthened development time and smaller-sized adults. For Ae. aegypti, but not Ae. albopictus, high competition conditions and the presence of malathion independently and not interactively led to an increase in virus dissemination from the midgut. Our results suggest that larval competition and chemical contaminants may influence disease transmission directly by altering adult mosquito fitness and indirectly by altering vector interactions with arboviruses.

Can Horton Hear the Whos? The Importance of Scale in Mosquito-Borne Disease

“…2009, 2010). Environmental conditions encountered during immature stages may also affect adult mosquito barriers to susceptibility (e.g., Takahashi 1976; Grimstad and Haramis 1984; Alto et al 2008a,b; Westbrook et al 2010; Muturi and Alto 2011; Muturi et al 2011). Interactions between environmental and biological factors may generate a complex landscape of infectious vectors that determines transmission dynamics and risk.…”

Impact of inter‐ and intra‐specific competition among larvae on larval, adult, and life‐table traits of Aedes aegypti and Aedes albopictus females

“…As insects that live in two distinct environments (larval - aquatic and adult - terrestrial), mosquitoes experience varied biotic interactions that impact individual morphological, physiological, and behavioral traits (e.g., wing length, blood-feeding success, lipid reserves; Schneider et al , 2011), life-history traits closely associated with fitness (survival, fecundity) (Carrington et al , 2013), and ultimately, population growth (Livdahl & Willey, 1991; Juliano, 1998). Any biotic or abiotic factors that affect adult mosquito phenotypes may also alter the transmission potential of associated pathogens (i.e., vectorial capacity) (Grimstad & Walker, 1991; Muturi et al , 2011; Alto & Bettinardi, 2013). …”

Insecticide-Mediated Shift in Ecological Dominance between Two Competing Species of Grain Beetles

“…Environmental disturbances, such as insecticide application and the resulting seed contamination, potentially interfere with the availability and suitability of the shared resources, affecting competitive interactions and their expected outcome. Curiously, insecticide-mediated competitive interactions have seldom been investigated, and the few previous investigations have focused primarily on intraspecific competition [16], [40]–[42]. In this study, we tested the effect of insecticide disturbance as a mediator of intra- and interspecific competition in two cereal grain beetle (pest) species characterized by internal feeding.…”

“…This phenomenon is termed “competition release” and has been proposed and successfully tested in amphibians and mosquitoes subjected to intraspecific competition [41], [42]. Competition release is a potential cause of pest resurgence (i.e., an increase in the abundance of the targeted arthropod pest species to a level exceeding that of uncontrolled populations following insecticide (or acaricide) application), but never tested [44], [45].…”