Background Wolbachia are a group of maternally inherited intracellular bacteria known to be widespread among arthropods. Infections with Wolbachia cause declines of host populations, and also induce host resistance to a wide range of pathogens. Over the past few decades, researchers were curious to use Wolbachia as a biological tool to control mosquito vectors. During the present study, assessment of the prevalence of Wolbachia infections among wild mosquito populations in Sri Lanka where mosquito-borne diseases are a major health concern, was carried out for the first time. DNA was extracted from the abdomens of mosquitoes, collected from seven provinces, and screened for the presence of Wolbachia by PCR using wsp and groE primers. Group-specific and strain-specific primers were used to classify Wolbachia into the supergroups A and B, and into the strains Mel, AlbA and Pip. ResultsA total of 330 individual mosquitoes belonging to 22 species and 7 genera were screened. Eighty-seven mosquitoes (26.36%) belonging to four species (i.e. Aedes albopictus, Culex quinquefasciatus, Armigeres subalbatus and Mansonia uniformis) were positive for Wolbachia infections. Primary vector of the dengue fever, Ae. aegypti was negative for Wolbachia infections while the secondary vector, Ae. albopictus, showed a very high infection rate. The filarial vector C. quinquefasciatus had a relatively high rate of infection. Japanese encephalitis vectors C. gelidus and C. triteaneorynchus, and the Anopheles vectors of malaria were negative for Wolbachia infections. Nine sequences of Wolbachia-positive PCR products were deposited in the GenBank and compared with other available data. Aedes albopictus was infected with both Wolbachia strains A (AlbA) and B (Pip) supergroups. Phylogenetic analysis of the wsp sequences showed two major branches confirming identities obtained from the PCR screening with strain-specific primers.Conclusion Wolbachia infections were found only among four mosquito species in Sri Lanka: Aedes albopictus, Culex quinquefasciatus, Armigeres subalbatus and Mansonia uniformis. Sequence data showed high haplotype diversity among the Wolbachia strains.

Background The tropical bed bug, Cimex hemipterus , is a serious indoor public health pest in tropical regions causing intense physical discomfort and mental distress to humans. At present, the application of insecticides is the major control strategy. The present study was designed to evaluate the development of resistance and resistance mechanisms in Cimex hemipterus from Kandy district, Sri Lanka. Methods The resistance status of the collected bed bugs was determined against the discriminative dosages of DDT, malathion, propoxur, deltamethrin and permethrin by conducting bioassays according to World Health Organization guidelines. Activities of insecticide metabolizing enzymes, i.e. esterases, glutathione S-transferases (GST) and monooxygenases, and the insensitivity of organophosphate/carbamate target site acetylcholinesterase (AChE), were evaluated by biochemical assays. Regions of the gene of the pyrethroid/DDT target site, the voltage-gated sodium channel regulatory protein (VGSC), were sequenced for possible kdr mutations. Results Survival percentages of bed bug population were 71, 68 and 51% for DDT, malathion and propoxur respectively. KT 50 and KT 90 values, calculated using log-probit mortality curves for deltamethrin were 62.55 and 123.96 h, respectively. These values were much higher for permethrin where KT 50 was 201.10 h and the KT 90 was beyond the detectable range. Results were compared with previous values reported for the same population in 2002. Resistance to propoxur has increased significantly from 11 to 51% with about a 20-fold increase in the number of individuals with elevated esterase mechanism. No significant change has occurred in malathion and DDT resistance, in GST and monooxygenase activities, and in AChE sensitivity for the past 14 years. Six kdr associated mutations (Y/L995H, V1010L, I1011F, L1014F, V1016E, L1017F/S) and a non- kdr associated mutation (A1007S mutation) were found from the α-region of the VGSC gene. Out of the kdr type mutations, only L1014F has been reported previously form C. hemipterus while the others have been reported from other insects. Conclusions The bed bug population has developed high resistance to propoxur with increased esterase activities. KT 50 for deltamethrin and permethrin has increased 125- and 20-fold, respectively, over the period 2002 to 2016. To the authors’ knowledge, this is the first time that the possible involvement of a kdr type mutation in developing pyrethroid resistance in C. hemipterus has been shown in Sri Lanka.

We report the larvicidal impacts of four different morphologies of zinc oxide nanoparticles (ZnO NPs) [star-shaped (S), needle-like (N), plate-like (P), and cubical (C)] on mosquito larvae of Aedes albopictus and Anopheles vagus.

1. Resource partitioning is a critical component in competing species that coexist in a community. The biting behaviour of coexisting frog‐biting mosquito species associated with a tropical anuran community is investigated. 2. Monthly samplings were taken for 2 years at two study sites in central Sri Lanka to collect frog‐biting mosquitoes, anuran abundance, environmental data, and interactions between mosquitoes and anuran hosts. Mosquitoes were collected using mouth‐operated aspirators and sound traps broadcasting anuran calls. Mosquitoes were identified using taxonomic keys and DNA barcodes. 3. A total of 1079 frog‐biting mosquitoes from four species belonging to two genera were collected [Uranotaenia rutherfordi (5%), Ur. morphotype 1 (67%), Ur. morphotype 2 (21%), and Mansonia uniformis (7%)]. Species‐specific interactions between Uranotaenia mosquitoes and their anuran host were found. Uranotaenia morphotype 1, the most common species, was mainly attracted (99%) to Duttaphrynus melanostictus. Uranotaenia rutherfordi was mainly attracted (95%) to Pseudophilautus rus, while Ur. morphotype 2 was attracted (97%) to Polypedates cruciger. These Uranotaenia species are active at different hours at night that correspond to the peak calling activity of their anuran host. Each Uranotaenia species was active at heights that coincide with the calling sites of their host. In contrast, Ma. uniformis was non‐specific in host choice and was equally distributed in space and time with respect to host feeding. 4. Here, previously unknown feeding patterns of co‐occurring frog‐biting mosquito species and their interactions with anurans present in their community are reported, highlighting the existence of complex behavioural patterns of these mosquito communities.

It is indisputable that invasive plant species strongly impact the ecosystems they invade. Many of such impacts can be negative and threaten the local species through competition, environmental change, or habitat loss. However, introduced plants may also have positive roles in the ecosystems they invade. This review extracted information from reports on common gorse (Ulex europaeus), one of the top 100 invasive plants on the earth, including its detrimental effects and potential beneficial roles in invaded ecosystems. The reduction of native fauna and flora are the main harmful effects of common gorse identified by the literature review. Soil impoverishment and fire hazards are other negative impacts reported for common gorse that could affect agricultural systems and local economies. Despite the negative impacts, reports of positive ecological services provided by common gorse also exist, e.g., as a nursery plant or habitat for endangered native animals. We also reviewed the known human uses of this plant that could support management strategies through harvest and benefit the local communities, including its use as biofuel, raw matter for xylan extraction, medicine, and food. Finally, our review identified the gaps in the literature regarding the understanding of the beneficial role of common gorse on native ecosystems and potential human uses, especially in the tropics.