Behavioural response of Culex pipiens biotype molestus to oviposition pheromone.

Insect behaviour relies on an olfactory sensory system that controls a range of activities, from food choice and mating to oviposition, where pheromones play a central role. In Culex mosquitoes, egg-laying is accompanied by the release of mosquito oviposition pheromone (MOP), which has been shown to affect the oviposition behaviour of conspecifics. Here, we investigated for the first time the effect of MOP on the oviposition rate of Culex pipiens biotype molestus, examining separately males and females, before and after mating and oviposition. Our results demonstrate that MOP is more likely to act as an oviposition stimulant rather than an attractant, since more gravid females laid eggs in its presence, while the number of male or female mosquitoes (virgin or mated) captured on pheromone-treated pots was similar to those treated with control water.

Entomological Surveillance Activities in Regions in Greece: Data on Mosquito Species Abundance and West Nile Virus Detection in Culex pipiens Pools (2019-2020).

Human cases of West Nile virus (WNV) infections have been recorded in Greece since 2010, with seasonal outbreaks (summer-autumn) on an almost annual basis, caused mainly by the WNV lineage 2 strain (Nea Santa-Greece-2010). National Public Health Organization (NPHO) in Greece is annually implementing enhanced surveillance of human WNV infection, in order to promptly identify human cases of WNV infection and monitor distribution in terms of time and place. Entomological surveillance activities were carried out on a national basis in 2019 and 2020, under NPHO coordination and the collaboration of several private subcontractors, along with the Unit of Medical Entomology, Laboratory for Surveillance of Infectious Diseases (LSID). The aim was to monitor mosquito species composition, abundance, and WNV circulation in mosquito pools of Culex pipiens s.l. species. Adult mosquito traps were placed in selected sites; collected samples were morphologically characterized and pooled by date of collection, location, and species types. Female Culex pipiens s.l. pools were tested for WNV and WNV infection rates (MIR and MLE) were estimated. Highest mean number of female Culex pipiens s.l. species was recorded in Central Macedonia both for 2019 and 2020. Six hundred and fifty-nine mosquito pools (147 in 2019 and 512 in 2020) of female Culex pipiens s.l. were examined for WNV presence. The highest MLE was detected in Western Macedonia in 2019 and in Thessaly in 2020. Here, we present data on the mosquito species composition in the studied areas and WNV detection in mosquitoes from areas in Greece where the specific national mosquito surveillance program was implemented, for two years, 2019 and 2020.

Wolbachia infection suppresses both host defence and parasitoid counter-defence.

Endosymbiotic bacteria in the genus Wolbachia have been linked to several types of reproductive parasitism, which enhance their own transmission, while their direct effects on the host vary from beneficial to neutral or detrimental. Here, we report negative effects of infection on immunity-related traits of Drosophila simulans and the parasitoid wasp Leptopilina heterotoma. Infected D. simulans showed a reduced ability to encapsulate parasitoid eggs, compared to a tetracycline-treated, bacterium-free line. Challenging the two lines with a fungal pathogen, Beauveria bassiana, on the other hand, revealed no differences in survival. Moreover, elimination of Wolbachia was beneficial for the parasitoid wasp, as eggs laid by uninfected females suffered significantly lower encapsulation rates. We discuss possible origins of these fitness costs and their implications for infection dynamics and the interactions between host species.