Impacts of Lysinibacillus sphaericus on mosquito larval community composition and larval competition between Culex pipiens and Aedes albopictus

Abstract

Effectiveness of mosquito larvicide active ingredients (AI), such as Lysinibacillus sphaericus, varies between species, yet little is known regarding how differential effectiveness manifests in larval communities in applied settings. To examine how differential effectiveness of L. sphaericus influences larval community dynamics, we performed two experiments. We performed a field experiment in which containers were seeded with a standardized nutrient treatment, mosquitoes colonized the containers, and then containers received one of three L. sphaericus applications. We then performed competition assays between Culex pipiens and Aedes albopictus in low nutrient environments using multiple interspecific ratios and the presence/absence of a low dose of L. sphaericus. Field results demonstrated elimination of Culex spp. from treated containers while container breeding Aedes spp. proliferated across all treatments. Lysinibacillus sphaericus did not influence competition between Cx. pipiens and Ae. albopictus, and the L. sphaericus application eliminated Cx. pipiens in all treatment replicates while survival of Ae. albopictus was similar between treated and untreated containers across interspecific ratios. Lysinibacillus sphaericus is an effective AI for control of Culex spp. However, different AIs should be utilized in habitats containing non-Culex genera while a mix of AIs should be utilized where coexistence of multiple genera is expected or confirmed.

Natural products from Xenorhabdus and Photorhabdus show promise as biolarvicides against Aedes albopictus

“…Reportedly, Aedes species are less susceptible to L. sphaericus. 74,75 As for the longevity, spinosad, vectomax and vectobac maintained their efficacy for 15 days whereas, there was a downward trend in effects of fabclavine from >94% to approximately 15%. The growth culture of X. nematophila has been observed to have a short longevity in water maintaining 100% efficacy against Ae.…”