Emergence, feeding and oviposition behaviour of Anopheles arabiensis: a vector from Mamfene in KwaZulu-Natal (South Africa)

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Abstract Background Malaria is a disease of public health importance. To eliminate malaria from KwaZulu-Natal, new strategies are needed to increase the impact of existing interventions. Greater attention is being given to controlling the larval stages, as a complementary measure to indoor residual spraying. However, there is limited information available on bionomics of this South Africa mosquito vector. To fill ithe knowledge gaps in vector bionomics, this study interrogated the emergence, feeding and oviposition behaviour of Anopheles arabiensis. Methods To observe the number of eggs laid per F1 An. arabiensis female, 300 fully gravid mosquitoes were individually placed into breeding tubes which were observed hourly from 18h00 to 06h00 and number of eggs laid by each female was recorded. Egg hatch rate was measured. Immediately after oviposition, the female mosquitoes were offered a blood meal to determine the duration post laying it took to refeed. To observe emergence times and sex ratios, a total of 4000 F1 pupa were placed in large containers which were observed hourly from 18h00 to 06h00. The newly erupted mosquitoes were collected and placed in bug-dorm cages. A sample of the newly erupted female mosquitoes were removed from the cages and placed individually into a test container and offered a blood meal. The female was then observed for a probing behaviour indicating its willingness to feed. Results Oviposition studies revealed two peaks corresponding with late evening and just before dawn. Most eggs were laid in the first half of the night (18h00 – midnight). Most mosquitoes erupted just after sunset and the sex ratios showed twice as many females as males emerged from pupae. Females readily took a bloodmeal after oviposition or just after emerging. Hatch rate to viable first instar larvae was 74.5%. Conclusions This study provided information on egg laying, hatch rates, emergence times, feeding behavior and sex ratios. The sex ratio of emerging mosquitoes is biased to females. The feeding behaviour suggests that the use of control interventions close to known vector breeding sites would be a tool to eliminate many males and females seeking sustenance soon after emergence or oviposition.

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