On the Biological Regulators of Bloodsucking Blackflies(Diptear:Simuliidae)of Mixed Forests of Belorussian and Ukrainian Woodlands

This article considers the natural regulators of blood-sucking Simuliidae subzone of mixed forests on the territory of Belarus and Ukraine.In the mixed forests,the major regulators of preimaginal phases of bloodsucking blackflies are microsporidia(Polidyspirenia simulii,Polidyspirenia sp.,Thelohania fibrata,Amblyospora bracteata,A.varians),fungi and mermithides(Gastromermis boophthorae).Caddisfly larvae(Hydropsyche angustipennis,Neureclipsis bimaculata,Polycentropus flavomaculatus,Cyrnus flavidus,Oligostomis reticulata,Brachycentrus subnubilus and Rhyacophila nubila)and fishes(Scardinius erythrophthalmus,Rutilus rutilus,Carassius carassius,Gobio gobio)significantly reduce the number of blackflies larvae and pupae.Adult blackflies are eaten by spiders(Araneus diadematus)dragonflies,robberflies,wasps,frogs(Rana temporaria and Rana terrestris),and insectivorous birds(Delichon urbicum,Hirundo rustica,Apus apus).Bactolarvicid and BLP-2477 are among the most effective biological products.

Evaluation of the physicochemical indices of blackflies(Diptera:Simuliidae)breeding sites in Delta State,Nigeria:Implication for onchocerciasis control

Objective:To determine the ecological parameters affecting the distribution of Simulium damnosum immature stages in some rivers within the endemic areas of Delta State,Nigeria.Methods:Onchocerca larvae were observed and identified for each river.An average sized colander with fine mesh was used to scoop the area to obtain the larvae along with other benthos.Physiochemical characteristics of the water at breeding sites were analyzed for a 12 months period.Correlation analysis was performed to establish the association between the larval densities and physicochemical parameters of blackfly.Results:The seasonal variation in the physical and chemical characteristics of these environments impaired the population dynamics of blackflies.The physicochemical parameters significantly varied among breeding sites(P<0.05),in which the temperature of surface water ranged between 23.2°C and 30.3°C,water flow velocity ranged between 0.4 and 1.3 m/s,dissolved oxygen ranged between 5.1 and 9.0 mg/L and pH ranged between 5.4 and 7.4.The mean collection of Simulium larvae was the highest in River Otor(44.1)and the least in River Namormai(19.1).There was significant difference(P<0.05)in the number of larvae collected from the sampled rivers.Also,the number of larvae collected significantly correlated with surface water temperature,water flow velocity,dissolved oxygen and pH.Conclusions:This study identified significant correlations between physicochemical parameters and blackfly larvae densities thus providing a precontrol evidence-based data for the control of onchocerciasis in the endemic areas of North Delta.

Physico-chemical indices of breeding sites of Simulium damnosum in the lower Cross River Basin, Nigeria

To determine the factor influencing the abundance development and distribution of Simulium damnosum(S.I) immature stages in the lower Cross River Basin, Nigeria, the physico-chemical characteristics of water at breeding sites were analysed longitudinally over a 12 month period. Analysis of the water samples showed that water current correlated positively and significantly(p<0.05), with dissolved oxygen(r = 0.95 vs 0.10); conductivity(r = 0.95 vs 0.81); hydrogen ion concentration(r = 0.03 vs 0.46); and biochemical oxygen demand(r = 0.80 vs 0.64); from Agbokim Waterfalls and Afi River respectively. The result indicates that these parameters and low ionic concentration are the most essential requirement for the development of S. damnosum pre-imaginal stages. Amplitudes of annual variability as measured by co-efficient of variation varied between the parameters. From the trends in hydrological variables it was deduced that the integrated impact of precipitation, input of surface runoff and municipal effluents played an overriding role in determining the absolute levels and temporal pattern in the water quality attributes. Of the 3578 pre-imaginal stages of S. damnosum collected, 52.52% and 47.4% were collected from Agbokim Waterfall and Afi River respectively. There was a significant difference(p<0.05) in the number of pre-imaginal stages collected from both sites. The highest number of pre_imaginal stages of S. damnosum collected were at the peak of rain(July—September) indicating that S. damnosum in the River Basin is a wet season breeder. The need for long term laboratory colonization of blackfly immature stages becomes imperative especially how these parameters could be exploited in control programme through the testing of larvicides without adverse ecological damage to the aquatic habitat.

Differential effects of environmental climatic variables on parasite abundances in blue tit nests during a decade

Models on climate change have predicted an increase of temperature over the earth’s surface with potential drastic effects on living organisms.We analyzed the relationships between climatic conditions(temperature,rainfall,and wind speed)and the abundance of blood-sucking flying insects(biting midges and blackflies)and nest-dwelling ectoparasites(mites,fleas,and blowflies)collected from blue tit nests during bird breeding seasons for a period of 10 years.Average temperature,rainfall,and wind speed showed significant differences among years.Temperature and wind speed increased during the period of study while rainfall decreased.Biting midge,blackfly,and blowfly abundances increased across years but not flea and mite abundances.Hatching date decreased and brood size increased across years.Independently of year variation,parasites were related to climatic variables.For example,biting midge,blowfly,mite,and flea abundances were positive and significantly related to average temperature.We also found a positive and significant relationship between abundances of Haemoproteus infections and biting midge abundances during the first year of life of birds out of nests.However,abundance and prevalence of Lankesterella infections in yearlings were positive and significantly related to mite abundances during the year of birth of birds.Leucocytozoon and Lankesterella infections were also significantly related to climatic variables and Haemoproteus and Lankesterella infections increased across years.In addition,body condition of adult females and males were negatively related to flea larvae and blowfly abundance respectively.Nestling body condition was also negatively related to biting midge abundance.Changes in climatic conditions across years could therefore affect several parasites of birds but also to birds themselves.