Field Evaluation of a Newly Introduced Thiamethoxam Insecticide and Neem Seed Water Extract Against the Predator Hippodamia Variegata in Sudan

Naturally occurring biological control agents play an important role in suppressing many important agricultural insect pests under normal conditions. Regrettably, many synthetic pesticides are reported to impose negative impacts on beneficial insects. Therefore, considerable efforts are devoted in recent years to choose selective insecticides for combating noxious pests. Accordingly, field experiments were conducted on potato crop during two consecutive winter (December-March) seasons at Shambat Research Station, Khartoum North, Sudan, to study the side effects of a newly introduced insecticide Actara (thiamethoxam) 25 WG, applied at different rates, and neem seed kernel water extract (NSKWE) at two rates, on larvae of the coccinellid predator, Hippodamia variegata. The results indicated that Actara was toxic (IOBC class 4) to the larvae of H. variegata under the two experiments, while NSKWE was found to be safe to the predator. Such neem extract at its two rates (2.5% and 5%w/v) showed significantly the highest numbers of the predator in the two experiments. It is concluded that the tested neem treatments can be used safely against potato pests without adverse effect on the predatory larvae of H. variegata, but Actara should be avoided when natural enemies are active.