The impact of the insecticide cypermethrin on the functional response, predatory behaviour and mating behaviour was studied in a non-target potential reduviid biological control agent Acanthaspis pedestris (Sta˚l). The intensity of abnormal behaviour increased as the concentration of cypermethrin was increased. The insecticide negatively affected the functional response events such as attack ratio, handling time and rate of discovery. Cypermethrin also reduced the predatory efficiency and prolonged the mating events in A. pedestris. The type II (decelerating curve) of functional response was altered into a type IV (dome-shaped curve) by cypermethrin.

Relative toxicity of two commonly used insecticides namely cypermethrin (Cymbush 10 EC) and fenvalerate (Sumicidin 20 EC) to the non -target reduviid predator Rhynocoris marginatus was evaluated. Among the two insecticides tested, fenvalerate was more toxic than cypermethrin. Both cypermethrin and fenvalerate increased the number of prohaemocytes and granular haemocytes and decreased the plasmatocytes. They also caused changes in the density of cystocytes and oenocytoids. Though both the insecticides increased the total haemocyte counts, highest impact was caused by fenvalerate.