Toxicity of fenitrothion, an organophosphorus pesticide, against summer population of sunn pest, Eurygaster integriceps Put. (Hemiptera: Scutelleridae)

The sunn pest are a group of insect representing several genera of the shield bug (Scutelleridae) and stink bug (Pentatomidae) families, with the species Eurygaster integriceps being the most economically important. The sunn pest is a major pest of wheat and barley in central and western Asia and it accounts for annual losses of 20-30% for barley and up to 100% for wheat. In the recent decades problems have intensified largely due to change in farming practices. Thus this pest threatens food security and reduces the stability of traditionally wheat-based agricultural systems. In order to control pest, the major organophosphorus insecticide used is fenitrothion. So, the aim of the current study was to determine toxicity of fenitrothion against summer population of adult sunn pest. Insecticide toxicity was measured using a topical bioassay. To do so, the toxin was dissolved in acetone and six concentrations of toxin including 25, 50, 100, 150, 175 and 200 ppm were prepared. Insects were treated on the pronotum with one micro litre aliquots of insecticide in acetone (for treatments) or acetone alone (for control). The dose-mortality relationship was assessed from above mentioned doses with 30 insects treated per dose. After treatment, insects were maintained at laboratory conditions and mortality was recorded after 48 hours. Results were corrected for control mortality with Abbott's formula and then analyzed and toxicity determined. The obtained results showed that LD10, LD50, and LD90 were 34.7, 90.43, and 235.5, respectively.