Mosquito Larvae (Culex spp.) Startle Responses to Vibration Stimuli

We explored startle responses of Culex spp. larvae to varying frequencies and durations of vibrations, before investigating habituation (a behavioural learning phenomenon). The startle response consists of a rapid movement to permit escape from a potentially dangerous stimulus. We used the automated Zantiks MWP_vb unit to analyse larval startle responses through the built-in live video tracking. Set within the unit’s controlled environmental chamber, we recorded distance travelled by the larvae. These results were used to optimise the vibration startle response for use in habituation studies. Repeated vibrations appeared to reduce larvae startle responses, although further analysis is required to confirm habituation. This study not only provides an insight into the learning ability of mosquito larvae, but demonstrates the ease, replicability and control conferred by the automated unit. Furthermore, this method is applicable to many other organisms and shows potential for more sophisticated environmental effect testing, such as behavioural toxicology.

Behavioural Toxicology of Midge Larvae Chironomous sp. after Acute In Situ Exposure of Different Industrial Effluents and Drinking Water

Behavioural activities in relation to toxicological aspects involve behavioural changes of aquatic organisms under the exposure of a contaminant. The present study aims to know behavioural activities of midge larvae Chironomus sp. at the in-situ acute exposure of different chemicals containing wastewater viz. lead-acid battery industrial effluent, mixed industrial effluent and fresh tap water (chlorinated) as drinking water in comparison to control (dechlorinated) water sample (aged tap water). The Chironomus larvae were kept in three different experimental chambers (perforated wall test vessels) with the exposure of different water samples. These samples were made with no dilution, 50 % dilution, 2.5 % dilution and control water sample. The behavioral activities for larvae of Chironomus sp. were measured at 0h, 2h, 24h and 48 h in in-situ condition. The behavioral activities viz. crawling, looping, ventilation, paralyses and subsequently death of the larvae were recorded in the field condition. A significant differences (P < 0.05, P < 0.01 and P< 0.001) were observed with increasing time of exposure while in few cases the data were increased without significance level. It was recorded that after exhibiting behavioural activities viz. crawling, looping, ventilation and paralyses finally all species were died 100 % of the population in lead acid battery effluent following both 24h and 48hr exposure. In addition, death of larvae were 70 % in mixed industrial effluent and 50 % in fresh tap water (chlorinated) after 48h exposure as compared to control sample water. In conclusion, the present results indicate that the larvae of Chironomous sp. are suitable indicators in the evaluation of the effluent quality in the studied stream, potential to know by behavioural toxicological study for heavy metals and organic pollution. Although it is a preliminary observation by assessing behavioural toxicology but future study in relation to biochemical and genetic damage of Chironomous larvae with the exposure of toxic water samples will provide bigger view.