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Mosquitoes have a wide range of digestive enzymes that enable them to utilize requisite blood and sugar meals for survival and reproduction. Sugar meals, typically derived from plant sources, are critical to maintain energy in both male and female mosquitoes, whereas blood meals are taken only by females to complete oogenesis. Enzymes involved in sugar digestion have been the subject of study for decades but have been limited to a relatively narrow range of mosquito species. The southern house mosquito, Culex quinquefasciatus, is of public health importance and seldom considered in these types of studies outside of topics related to Bacillus sphaericus, a biocontrol agent that requires interaction with a specific gut-associated α-glucosidase. Here we sought to describe the nature of α-glucosidases and unexplored β-glucosidases that may aid Cx. quinquefasciatus larvae in acquiring nutrients from cellulosic sources in their aquatic habitats. Consistent with our hypothesis, we found both α- and β-glucosidase activity in larvae. Interestingly, β-glucosidase activity all but disappeared at the pupal stage and remained low in adults, while α-glucosidase activity remained in the pupal stage and then exceeded larval activity by approximately 1.5-fold. The expression patterns of the putative α- and β-glucosidase genes chosen did not consistently align with observed enzyme activities. When the α-glucosidase inhibitor acarbose was administered to adults, mortality was seen especially in males but also in females after two days of exposure and key energetic storage molecules, glycogen and lipids, were significantly lower than controls. In contrast, administering the β-glucosidase inhibitor conduritol β-epoxide to larvae did not produce mortality even at the highest soluble concentration. Here we provide insights into the importance of α- and β-glucosidases on the survival of Cx. quinquefasciatus in their three mobile life stages.

Culex pipiens complex is an important vector of epizootic and zoonotic pathogens, including West Nile virus. Chicago, Illinois and its suburbs have suffered high incidence of human West Nile virus infections in the past. This makes abatement programs in and around the Chicago area an essential service. The control of Cx. pipiens is often complicated by rapidly evolving resistance to pyrethroids, which are the most widely used chemical class in US mosquito abatement programs. The present study assessed Sumithrin® resistance in Cx. pipiens collected from five locations around Cook County, Illinois, neighboring the city limits of Chicago. According to CDC guidelines, samples from all five locations demonstrated some resistance to Sumithrin®. When assessed with Anvil®, a formulated product made of Sumithrin® synergized with piperonyl butoxide, susceptibility was rescued in mosquitoes from three out of the five locations, suggesting involvement of mixed-function oxidases and/or carboxylesterases in Sumithrin® resistance at these locations. Not all locations had susceptibility rescued by Anvil®, but these locations had relatively low knockdown resistance allele frequencies, suggesting that mechanisms other than knockdown resistance may be involved. Enzyme activities did not reveal any marked trends that could be related back to mortality in the bottle bioassays, which highlights the need for multiple types of assays to infer enzymatic involvement in resistance. Future directions in pyrethroid resistance management in Chicago area Cx. pipiens are discussed.

Adult house flies (Musca domestica L.) inhabiting dairy farms not only are nuisance pests but also harbor and disseminate bacteria. We examined the bacterial community composition, diversity, environmental sources, and prevalence in individual adult female house flies and cattle manure samples collected monthly from Florida, North Carolina, and Tennessee dairy farms between May and August 2021. Individual house flies carried diverse bacterial communities, encompassing all bacterial taxa (100%) identified across manure samples, and additional species likely acquired from the animals. Bacterial community assemblage in house flies and manure samples within farms varied by month. Some taxa were differentially associated with either house flies (Corynebacterium, Acinetobacter, and Staphylococcus) or manure samples (Treponema, Succinivibrio, and Clostridia). House fly bacterial communities mostly contained specialist species originating from manure, with several taxa (Escherichia, Corynebacterium, Turicibacter) being potential pathogens of livestock and humans. These findings further support the role of house flies as carriers of cattle-associated bacteria, including pathogens, and their potential for disseminating these microbes among cattle and to neighboring environments. Since their bacterial communities provide a snapshot of their surrounding environment, house flies also serve as effective sentinels in xenosurveillance strategies.

Updated by Edwin R. Burgess IV. Originally written by Phillip E. Kaufman and Emma N. I. Weeks, January 2016.

Dust bags are an effective method of horn fly and louse control. However, dust bags are only effective when hung in places where cattle are forced to use them. The best locations are areas where cattle must pass once or twice a day, or every other day, for instance between mineral boxes or water and pasture. During the field tests, forced-use dust bags provided an average of 90% horn fly control. Production was increased by an average of 34% over the normal management practice. This increase in production was equivalent to 1/3 lb/animal/day. This 5-page fact sheet was written by P. E. Kaufman and E. N. I. Weeks and originally published by the UF Department of Entomology and Nematology, November 2012. This version February 2022. http://edis.ifas.ufl.edu/ig135

As resistance to the limited number of insecticides available for medical and veterinary pests becomes more widespread, there is an urgent need for new insecticides and synergists on the market. To address this need, we conducted a study to assess the toxicity of three monoterpenoids—carvone, menthone, and fenchone—in comparison to permethrin and methomyl against adults of two common pests: the yellow fever mosquito (Aedes aegypti) and the house fly (Musca domestica). We also examined the potential for these monoterpenoids to enhance the effectiveness of permethrin and methomyl when used together. Finally, we evaluated the ability of each monoterpenoid to inhibit acetylcholinesterase, comparing them to methomyl. While all three monoterpenoids performed relatively poorly as topical insecticides (LD50 > 4000 ng/mg on M. domestica; >6000 ng/mg on Ae. aegypti), they synergized both permethrin and methomyl as well as or better than piperonyl butoxide (PBO). Carvone and menthone yielded synergistic co-toxicity factors (23 and 29, respectively), which were each higher than PBO at 24 h. Currently, the mechanism of action is unknown. During preliminary testing, symptoms of acetylcholinesterase inhibition were identified, prompting further testing. Acetylcholinesterase inhibition did not appear to explain the toxic or synergistic effects of the three monoterpenoids, with IC50 values greater than 1 mM for all, compared to the 2.5 and 1.7 µM for methomyl on Aedes aegypti and Musca domestica, respectively. This study provides valuable monoterpenoid toxicity and synergism data on two pestiferous insects and highlights the potential for these chemistries in future pest control formulations.

Abstract Tick control tubes are a host‐targeted tick control method targeting immature Ixodes scapularis ticks attached to mice or found within mouse burrows and nests. Tick control tubes contain permethrin‐treated cotton inside cardboard tubes that mice use as nesting material. Ticks attached to mice or present in their burrows are exposed to the treated cotton. However, there have been variable results using these tubes for tick control. Rodent visitation and use of these tubes may influence their effectiveness. The aim of this study was to evaluate small mammal use of tick control tube cotton and to evaluate whether cotton size or odor attractants changed small mammal tube visitations and cotton removal. For the cotton size experiment, three different cotton sizes were used. In the odor attractant experiment, three different odor attractants were used (peanut butter, safflower oil, and vanillin) along with a commercially available tube as a control. A negative control group that had no cotton present in the tube was used for both experiments. Cotton loss was determined by weighing cotton in deployed tubes weekly, and mouse and nontarget species interactions were evaluated using camera‐trap data collected at each site. While the tested cotton sizes and odor attractants did not affect cotton use, mice did increasingly use cotton during cooler fall months, with the highest use of cotton in October and least use in July. These results suggest that mouse use of cotton was not related to cotton size or odor attractants but was dependent on season. This warrants future research on temporal small mammal use of tick control tubes to determine optimal deployment times for tick control.