Cheese or cheese infusions – ecological traps for mosquitoes and spotted wing Drosophila

We tested the hypothesis that the “ecological trap” phenomenon (a mismatch between a habitat’s perceived attractiveness and its actual quality, resulting in a population sink) is exploitable for pest control. We selected mosquitoes as modal organisms, because selection of an oviposition site by adult female mosquitoes in response to its perceived attractiveness is of paramount importance for the development and survival of their larval offspring. In laboratory and/or field experiments, we show that (i) each of five cheese varieties tested (Raclette, Pecorino, Brie, Gruyere, Limburger) strongly attracts females of both the yellow fever mosquito, Aedes aegypti, and the common house mosquito, Cx. pipiens; (ii) cheese infusions, or headspace odorant extracts (HOEs) of cheese infusions, significantly affect oviposition choices by Cx. pipiens and Ae. aegypti, (iii) HOEs contain at least 13 odorants; (iv) in field settings, cheese infusions more effectively stimulate oviposition by Cx. pipiens and Culiseta incidens than bluegrass (Poa sp.) infusions, and also capture (by drowning) the spotted wing Drosophila (SWD); (v) the microbe composition of home-made cheese infusions modulates oviposition choices by mosquitoes; and (vi) the type of cheese infusion coupled with its nutritional content strongly affects the survivorship of mosquito larvae. In combination, our data show that microbial metabolites associated with cheese and cheese infusions are both attractive to adult mosquitoes seeking hosts and oviposition sites, respectively, and are toxic to mosquito larvae. These microbes and their metabolites could thus be coopted for both the attract and the kill function of “attract & kill” mosquito control tactics. Implementation of customizable and non-conventional nutritional media, such as home-made cheese infusions, as microbe-based ecological traps presents a promising concept which exploits insect ecology for insect control.

Gynandromorphic Specimens of Culex erythrothorax, Culex pipiens Complex, Culex tarsalis, and Culiseta incidens Collected in Northern San Joaquin Valley, California

ABSTRACT Gynandromorphic insects bear both male and female characteristics. In mosquitoes, gynandromorphy has been documented in multiple species and it can include many different combinations of sex-specific traits such as plumose or filiform antennae, short or elongated palpi, and male or female terminalia. Here we report 4 gynandromorphic specimens of Culex erythrothorax, Cx. pipiens complex, Cx. tarsalis, and Culiseta incidens collected in the Northern San Joaquin Valley of California. Each of the specimens exhibited heads with female characteristics of short palpi and filiform antennae while displaying fully developed external male terminalia including basistyles and dististyles. The potential implication of gynandromorphism in genetic control of mosquito vectors is discussed.

New distribution records and range extensions of mosquitoes in British Columbia and the Yukon Territory

We report the first records of Aedes euedes Howard, Dyar, and Knab, and Coquillettidia perturbans (Walker) from Canada’s Yukon Territory, and the first record of Ae. decticus Howard, Dyar, and Knab from British Columbia. We also report range extensions in northern BC for the western treehole mosquito, Aedes sierrensis (Ludlow), the common house mosquito, Culex pipiens L., and the cool weather mosquito Culiseta incidens (Thomson).

Mosquito circadian flight rhythms: differential effects of constant light

The flight activity of Culiseta incidens was automatically recorded in constant darkness and constant light after entrainment to light:dark 12:12 to determine the usefulness of a formal circadian pacemaker model in which the periods of two oscillators respond reciprocally to light intensity. Period at activity onset lengthened approximately 0.4 h from darkness to 0.1 lx, whereas period at offset shortened approximately 0.4 h. Thus within this range, the onset of the nocturnal active phase obeyed Aschoff's rule for nocturnal animals, and the offset (or onset of diurnal rest phase) obeyed the rule for diurnal animals. These data supported a model in which, as light intensity increases, the period of one oscillator (evening) increases while that of another (morning) decreases. This model, with additional assumptions, also provided a framework for mutually consistent explanations of other features among the data. These included long periods at 3.5 lx, short periods at 35 lx, a progressively earlier occurrence of inactivity with increasing light intensity, and a clear example of circa-bi-dian (approximately 2 days) rhythmicity.

Arachidonic acid requirement for two species of Culiseta reared on synthetic diet

Culiseta incidens and Culiseta inornata larvae were successfully reared under aseptic conditions on a completely defined chemical medium. Arachidonic acid is an essential nutrient for both species. Larvae of C. incidens would develop and pupate in the absence of this fatty acid but emergence was impaired and none of the resulting adults could fly. None of the C. inornata larvae reared on diets lacking arachidonic acid became adult. Many of the C. inornata adults that emerged from diets containing this fatty acid could fly. Amino acid concentrations in the diet of 0.9% were superior to 1.4% for C. inornata. Asparagine was shown to be an essential nutrient for C. incidens; its nutritional effects were not tested on C. inornata.