Larvicidal activity of neem oil (Azadirachta indica) formulation against larva of Aedes albopictus mosquitoes to improve animal welfare

Aside from their importance as vectors of disease agents of animals, mosquitoes are a cause of irritation, blood loss, and allergic reactions. They can also disrupt normal behaviour of livestock. For cattle mosquito bites can result in decreased weight gains and milk production. Aedes albopictus, known as “tiger mosquito”, is an asiatic insect, widespread in all continents and recorded also in Italy. The mosquito fight is directed especially against larvae. This is because the fight against adults is temporary, unsatisfied, and polluting for the environment, while larval treatment is more localized in time and space, resulting less dangerous. The aim of our work is to develop new natural antimosquitos formulations (the neem oil, p.a. azadirachtin) that result not toxic. It is important to develop new antimosquitos drugs to supply the farmacoresistance of the used products. Among various tested substances the neem oil (p.a. azadirachtin) has shown good activity. The neem oil (AZ 0.3%) was tested at different concentrations: 0.005 g; 0.01 g; 0.025 g; 0.05 g, 0.075 g on larvae at the L1-L2 stage and larvae at the L3-L4 stage and control. 4 replicas were performed. The conditions were a 14-hour photoperiod and an average water temperature of 25 ° C. At the lowest doses (0.05 g and 0.01 g) the mean total death larvae compared to the control is not statistically significant. The doses 0.025 g, 0.05 g and 0.75 g are all equally effective completely eliminating all the larvae. Highly significant differences were found between the 3 doses and the control. Analyzing the results up to the eighth day of treatment, the day when the larvae in the control tests were either completely transformed into adults (48%) or death (52%), differences in the timing of elimination of larvae between different doses was recorded. At the dose of 0.005 g at the eighth day, 48% were dead and another 1% died within 17th days. At the dose of 0.01 at the eighth day, 61% of the larvae were dead, 10% died within 56th days. At the dose of 0.025g on the eighth day 85% of the larvae were eliminated and all died at the 26th day, at dose of 0.05g after 8 days 94% were eliminated and all larvae died in 21st days, and at a dose of 0.75g all larvae died in 7 days. The results obtained may be considered interesting, because the larvicidal Neem oil could be used in the fight against Aedes albopictus with the dose 0.075 g the most effective in terms of timing.