Browsing by Author "Mazigo, Ernest"

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    Impact of egg storage on hatchability and life history traits in anopheles gambiae sensu strict
    (University of Dar es Salaam, 2018) Mazigo, Ernest
    Mass rearing of Anopheles mosquito eggs is a critical process underlying the concept of sterile insect technique, a novel malaria vector control strategy. However, there is limited information on the impact of storing An. gambiae eggs at different conditions on their life history traits. The aim of this study was to assess the impact of storing An. gambiae s.s. eggs at 4°C and 48 ± 2% RH on hatchability, larval development, larval survivorship and emerged adult mosquito sex ratios. The study was conducted at Tropical Pesticides Research Institute. An. gambiae s.s eggs laid by 5 to 6 days adult mosquitoes were collected from Tropical Pesticides Research Institute insectaries. The eggs were then stored at 4°C and 48 ± 2% RH for 5, 10 and 15 days at density of 40, 80 and 120 eggs. Freshly hatched eggs at same hatching densities were used as controls. Experiments were repeated 6 times. We found that, hatching rates significantly decreased in eggs stored for 10 and 15 days (P < 0.05) but not in eggs stored for 5 days. There were no significant differences between An. gambiae eggs stored for 5 days and freshly hatched eggs (P > 0.05). Anopheles larvae development (L1 to pupae) was not affected by storage time across all hatching densities. We also found no significant differences in larval survivorship between freshly hatched eggs and eggs stored for 5 and 10 days at all hatching densities (P > 0.05) but not for eggs stored for 15 days. Furthermore, there was a significance decrease in proportions of adult males Anopheles mosquitoes emerged from eggs stored for 15 days (P < 0.05) but not for eggs stored for 5 and 10 days. From this study it was concluded that, storing An. gambiae s.s eggs at 4°C and 48 ± 2% RH for 5 days is an optimal condition and time that did not affect eggs hatching rates, larval development and survivorship and emerged adult mosquitoes sex ratios. Findings from the present study can be used in establishment of An. gambiae mass rearing protocols important for sterile insect technique.