Effect of juvenile hormone inhibitors on mature nymph of the sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), in vitro

The Sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), is one of the most important pest of wheat in Iran and some neighboring countries. The nymphs and adults cause sever quantitative and qualitative damage by feeding on leaves, stems and grains. Unfortunately, pesticide application is the main method of the sunn pest control, so finding the alternative methods are important. Precocene which is a juvenile hormone inhibitor, exerts cytotoxic effects on corpora allata of insects species, resulting necrosis of parenchymal cells, the source of juvenile hormone. At laboratory studies, precocene I and precocene II with different concentrations (0, 20, 25, 32, 40 and 50 μg) were applied topically to the thoracic surface of the fifth instar nymphs. The results showed that percent mortality increased with increasing concentrations of the hormones. The highest mortality (50%) was observed in concentration of 50 μg precocene II. Treated nymphs with precocene I and II led to appearing of deformed insects in fifth instar and adults. Also, the morphological abnormalities such as strong deformation of wings and hemelytron and persistence of old cuticles were observed. Increasing nymphal period was also resulted using precocenes