Diversity and Genetic Reassortment of Keystone Virus in Mosquito Populations in Florida.

Keystone orthobunyavirus (KEYV), a member of the genus Orthobunyavirus, was first isolated in 1964 from mosquitoes in Keystone, Florida. Although data on human infections are limited, the virus has been linked to a fever/rash syndrome and, possibly, encephalitis, with early studies suggesting that 20% of persons in the Tampa, Florida, region had antibodies to KEYV. To assess the distribution and diversity of KEYV in other regions of Florida, we collected > 6,000 mosquitoes from 43 sampling sites in St. Johns County between June 2019 and April 2020. Mosquitoes were separated into pools by species and collection date and site. All pools with Aedes spp. (293 pools, 2,171 mosquitoes) were screened with a real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assay that identifies KEYV and other closely related virus species of what was previously designated as the California encephalitis serogroup. In 2020, screening for KEYV was expanded to include 211 pools of Culex mosquitoes from sites where KEYV-positive Aedes spp. had been identified. rRT-PCR-positive samples were inoculated into cell cultures, and five KEYV isolates from Aedes atlanticus pools were isolated and sequenced. Analyses of the KEYV large genome segment sequences revealed two distinct KEYV clades, whereas analyses of the medium and small genome segments uncovered past reassortment events. Our data documented the ongoing seasonal circulation of multiple KEYV clades within Ae. atlanticus mosquito populations along the east coast of Florida, highlighting the need for further studies of the impact of this virus on human health.

Experimental removal of invasive Africanized honey bees increased breeding population size of the endangered Lear's macaw.

BACKGROUND: Invasive Africanized honey bees potentially compete with cavity-nesting birds in South America. However, the impacts of this competition and its conservation consequences to threatened species are poorly known. We quantified the presence of these bees and assessed their competition for cliff cavities used by nesting Lear's macaws Anodorhynchus leari, a globally endangered parrot endemic to the Caatinga biome of Brazil. We treated beehives with permethrin by shooting them with a crossbow bolt that distributed the compound upon impact. When feasible, we removed the comb and applied an insecticide (fipronil) to deter bee recolonization. We subsequently surveyed the macaw breeding population to verify whether our treatment allowed for nest recruitment in cavities previously occupied by bees. RESULTS: We recorded > 100 beehives in the nesting cliffs. Hives outnumbered macaw nests tenfold in two areas recently recolonized by macaws. Cavities occupied by bees were significantly higher than those occupied by macaws, suggesting that macaws may be forced to breed in lower cavities. None of the untreated cavities (n = 50) were occupied by nesting macaws, whereas 15% of treated cavities (n = 52) were occupied within 2 years post treatment. Treated cavities occupied by macaws were significantly higher than those not occupied. Hive management increased macaw breeding population by 71% of the macaw breeding population increase. CONCLUSION: Experimental hive treatments were effective in restoring nesting resources lost due to bee infestation. An intensive and continued eradication program is recommended to enhance macaw habitat restoration, facilitating its expansion into historical areas. © 2020 Society of Chemical Industry.

Evaluation of boric acid as toxic sugar bait against resistant Aedes aegypti mosquitoes.

Current methods of broad area application of contact insecticides used in mosquito control are becoming less effective, primarily due to resistance within mosquito populations. New methods that can deliver ingestible insecticides are being investigated as a means to mitigate resistance. This study evaluated insecticide delivery through toxic sugar baits (TSB) and resulting mortality of susceptible and resistant strains of Aedes aegypti. Two Ae. aegypti strains were evaluated using a 1% boric acid TSB: the susceptible Orlando 1952 (ORL) strain and the resistant Puerto Rican (PR) strain. The TSB resulted in high mortality for both ORL and PR strain of Ae. aegypti. Average mortality of female mosquitoes given TSB was 90.8% for PR and 99.3% for ORL. Our study suggests that targeting resistant mosquitoes with ingestible insecticides through TSBs could be a viable alternative to current mosquito control strategies and should be considered when developing an integrated vector management program.

PREFLEDGING MORTALITY AND THE ABUNDANCE OF MOSQUITOES BITING NESTLING BARN OWLS (TYTO ALBA) IN FLORIDA, USA.

Mosquito-borne diseases can have disastrous effects on avian populations; therefore, most studies of bird and mosquito interactions have focused on the mortality and morbidity associated with the diseases. However, the effect of mosquitoes feeding on birds, independent of disease, has not been well studied. We studied Barn Owls (Tyto alba) nesting in artificial nest boxes in sugarcane (Saccharum officinarum) fields in Florida, US. To reduce mosquito effects on nestlings, we used an insecticide spray in half of the nest boxes. Mosquito suction traps were fixed to the outside of eight nest boxes (four treated and four untreated) to collect mosquitoes over a 24-h period (one trap night) once weekly, from incubation until all nestlings fledged. Collected mosquitoes were counted, sorted into blood-fed and unfed females, and identified to species when possible. The dominant mosquito species captured were Culex nigripalpus, Mansonia dyari, and Mansonia titillans. The highest total number of mosquitoes and blood-fed mosquitoes captured in a suction trap in one trap night was 3,193 and 379, respectively. Overall, significantly fewer mosquitoes were captured from treated nest boxes compared to untreated boxes. Nestling age influenced the total number of mosquitoes captured, with the highest numbers associated with fledglings 22-42 d old. The highest numbers of blood-fed mosquitoes were captured when nestlings were 22-28 d old. Nestlings in insecticide-treated boxes had higher survival rates compared to those in untreated boxes during months with high mosquito numbers. Mosquitoes can impose energetic costs on nestlings by causing stress from irritation, dehydration, and the constant regeneration of blood cells. These costs, in addition to factors such as food shortage, temperature, and overall health of the nestling, can contribute to higher mortality rates during nesting periods with high mosquito numbers.

The Termite Fecal Nest: A Framework for the Opportunistic Acquisition of Beneficial Soil Streptomyces (Actinomycetales: Streptomycetaceae).

Mutualistic associations between insects and microorganisms must imply gains for both partners, and the emphasis has mostly focused on coevolved host-symbiont systems. However, some insect hosts may have evolved traits that allow for various means of association with opportunistic microbial communities, especially when the microbes are omnipresent in their environment. It was previously shown that colonies of the subterranean termite Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae) build nests out of fecal material that host a community of Streptomyces Waksman and Henrici (Actinomycetales: Streptomycetaceae). These Actinobacteria produce an array of bioactive metabolites that provides a level of protection for termites against certain entomopathogenic fungi. How C. formosanus acquires and maintains this association remains unknown. This study shows that the majority of Streptomyces isolates found in field termite fecal nest materials are identical to Streptomyces isolates from soils surrounding the nests and are not vertically inherited. A survey of Streptomyces communities from C. formosanus fecal nest materials sampled at 20 locations around the world revealed that all nests are reliably associated with a diverse Streptomyces community. The C. formosanus fecal nest material therefore provides a nutritional framework that can recruit beneficial Streptomyces from the soil environment, in the absence of long-term coevolutionary processes. A diverse Streptomyces community is reliably present in soils, and subterranean termite colonies can acquire such facultative symbionts each social cycle into their fecal nest. This association probably emerged as an exaptation from the existing termite nest structure and benefits both the termite and the opportunistic colonizing bacteria.

A Push-pull Protocol to Reduce Colonization of Bird Nest Boxes by Honey Bees.

Introduction of the invasive Africanized honey bee (AHB) into the Neotropics is a serious problem for many cavity nesting birds, specifically parrots. These bees select cavities that are suitable nest sites for birds, resulting in competition. The difficulty of removing bees and their defensive behavior makes a prevention protocol necessary. Here, we describe a push-pull integrated pest management protocol to deter bees from inhabiting bird boxes by applying a bird safe insecticide, permethrin, to repel bees from nest boxes, while simultaneously attracting them to pheromone-baited swarm traps. Shown here is an example experiment using Barn Owl nest boxes. This protocol successfully reduced colonization of Barn Owl nest boxes by Africanized honey bees. This protocol is flexible, allowing adjustments to accommodate a wide range of bird species and habitats. This protocol could benefit conservation efforts where AHB are located.

Extended disease resistance emerging from the faecal nest of a subterranean termite.

Social insects nesting in soil environments are in constant contact with entomopathogens but have evolved a range of defence mechanisms, resulting in both individual and social immunity that reduce the chance for epizootics in the colony, as in the case of subterranean termites. Coptotermes formosanus uses its faeces as building material for its nest structure that result into a 'carton material', and here, we report that the faecal nest supports the growth of Actinobacteria which provide another level of protection to the social group against entomopathogens. A Streptomyces species with in vivo antimicrobial activity against fungal entomopathogens was isolated from the nest material of multiple termite colonies. Termite groups were exposed to Metarhizium anisopliae, a fungal entomopathogen, during their foraging activity and the presence of Streptomyces within the nest structure provided a significant survival benefit to the termites. Therefore, this report describes a non-nutritional exosymbiosis in a termite, in the form of a defensive mutualism which has emerged from the use of faecal material in the nesting structure of Coptotermes. The association with an Actinobacteria community in the termite faecal material provides an extended disease resistance to the termite group as another level of defence, in addition to their individual and social immunity.

Resource competition between two fungal parasites in subterranean termites.

Subterranean termites live in large groups in underground nests where the pathogenic pressure of the soil environment has led to the evolution of a complex interaction among individual and social immune mechanisms in the colonies. However, groups of termites under stress can show increased susceptibility to opportunistic parasites. In this study, an isolate of Aspergillus nomius Kurtzman, Horn & Hessltine was obtained from a collapsed termite laboratory colony. We determined that it was primarily a saprophyte and, secondarily, a facultative parasite if the termite immunity is undergoing a form of stress. This was determined by stressing individuals of the Formosan subterranean termite Coptotermes formosanus Shiraki via a co-exposure to the virulent fungal parasite Metarhizium anisopliae (Metch.) Sorokin. We also examined the dynamics of a mixed infection of A. nomius and M. anisopliae in a single termite host. The virulent parasite M. anisopliae debilitated the termite immune system, but the facultative, fast growing parasite A. nomius dominated the mixed infection process. The resource utilization strategy of A. nomius during the infection resulted in successful conidia production, while the chance for M. anisopliae to complete its life cycle was reduced. Our results also suggest that the occurrence of opportunistic parasites such as A. nomius in collapsing termite laboratory colonies is the consequence of a previous stress, not the cause of the stress.