Interactive effects of salinity and a predator on mosquito oviposition and larval performance

Abstract

Oviposition habitat selection (OHS) is increasingly being recognized as playing a large role in explaining mosquito distributions and community assemblages. Most studies have assessed the role of single factors affecting OHS, while in nature, oviposition patterns are most likely explained by multiple, interacting biotic and abiotic factors. Determining how various factors interact to affect OHS is important for understanding metapopulation and metacommunity dynamics. We investigated the individual and interactive effects of three water salinities (0, 15 and 30 p.p.t. NaCl added) and the aquatic predator Anisops debilis Perplexa (Hemiptera: Notonectidae) on OHS and larval performance of the mosquitoes Ochlerotatus caspius Pallas and Culiseta longiareolata Macquart (Diptera: Culicidae) in outdoor-artificial-pool and laboratory experiments. C. longiareolata inhabited only freshwater pools, strongly avoided pools containing A. debilis, and larvae experienced lower survival in the presence of A. debilis. Salinity concentration interacted strongly with the predator in affecting OHS and larval survival of O. caspius; oviposition increased with increasing salinity in the absence of the predator and decreased with increasing salinity in the presence of the predator. O. caspius larval survival in predator-free pools was lowest in freshwater and highest at intermediate salinity. In predator pools, survival was highest at high salinity, where predation rate was shown to be lowest in the laboratory. Our results highlight that assessing the role of single factors in affecting mosquito distributions can be misleading. Instead, multiple factors may interact to affect oviposition patterns and larval performance.

Pesticide‐mediated trophic cascade and an ecological trap for mosquitoes

“…During the initial pesticide application, while Anisops were present, there was no mosquito oviposition; the mosquitoes during this time of the season avoid ovipositing in the presence of A. sardea (Eitam et al 2002) and Anisops debilis (Silberbush et al 2014). On 23 April, we applied larvicide applications: Lossquito (Bti, 1200 international toxic units per mg; Biodalia, Yokneam, Israel) with a 30 mL/L solution (final concentration: 1.8 lL/L in the pools), Temeguard 25% (temephos, Temeguard, Israel) as a suspension formulation containing 25 g active ingredient per liter, at 0.0625% (final concentration active ingredient [a.i.…”

“…Six pools remained as the untreated controls. During the initial pesticide application, while Anisops were present, there was no mosquito oviposition; the mosquitoes during this time of the season avoid ovipositing in the presence of A. sardea (Eitam et al 2002) and Anisops debilis (Silberbush et al 2014).…”

“…Indeed, mosquito populations can recover from very low abundance after treatment as population growth and development occur relatively quickly (Lichtenberg and Getz 1985). Sensitivity to insecticides might be increased by biotic stressors (competitors, predators, pathogens) but also by abiotic stressors, such as salinity (Duchet et al 2010a, Silberbush et al 2014), hydroperiod length, and drought (McLachlan 1985, Jeffries 1994, making insecticide effects difficult to predict due to interrelated processes (Duquesne and Liess 2010). Sensitivity to insecticides might be increased by biotic stressors (competitors, predators, pathogens) but also by abiotic stressors, such as salinity (Duchet et al 2010a, Silberbush et al 2014), hydroperiod length, and drought (McLachlan 1985, Jeffries 1994, making insecticide effects difficult to predict due to interrelated processes (Duquesne and Liess 2010).…”

“…Mosquitoes are generally pioneer insects, that is, rapid colonizers, and fast recolonization might lead to higher abundances of mosquitoes than in undisturbed sites, due to loss of predators and competitors in disturbed breeding sites Liess 2010, Staats et al 2016). Sensitivity to insecticides might be increased by biotic stressors (competitors, predators, pathogens) but also by abiotic stressors, such as salinity (Duchet et al 2010a, Silberbush et al 2014), hydroperiod length, and drought (McLachlan 1985, Jeffries 1994, making insecticide effects difficult to predict due to interrelated processes (Duquesne and Liess 2010).…”

Differential oviposition and offspring success of gray treefrogs in the presence of an invasive fish

“…One trade-off may be between avoiding ovipositing in the presence of predators and avoiding ovipositing in the presence of competitors. For example, Kershenbaum et al (2012) found that below a certain larval density, adult mosquitoes avoid sites with predators, but above that threshold, they use both predator and predator-free sites; thus, mosquitoes may be evaluating competition risk vs. predation risk, and ultimately may choose predator sites over high competition sites (Silberbush et al 2014). In other words, the ovipositing females are choosing their oviposition sites to maximize fitness as expected from the ideal free distribution (Fretwell and Lucas 1970).…”