Effect of kaempferol on ecdysteroid titer and oocyte size via tachykinin-4 in cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

The cotton bollworm, helicoverpa armigera (hübner) is an important pest of many crops. here, effects of kaempferol on ecdysteroid titer in the ovaries, hemolymph andoocyte size via tachykinin-4 content of h.armigera were studied. third instar larvae of h. armigera were fed on artificial diet containing different concentrations of kaempferol for 8 days. kaempferol had insecticidal activity after 6 days. the highest level of larval mortality was approximately 36% in larvae fed diet containing 10μg/g of kaempferol for 8 days. competitive elisa showed that tachykinin-4 titer decreased clearly in the adult female moth's brain and hemolymph which fed on diet containing 5 and10μg/g kaempferol during their larval stage for 8 days.it also decreased ecdysteroid in the ovary and hemolymph of adult female.moreover, oocyte size was significantly decreased. on the other hand, the injection of tachykinin-4 into the hemocoel not only increased ecdysteroid titerin the ovary but also approximately 1.4 fold increases in oocyte size was observed. in conclusion, feeding on food containing kaempferol decreased tachykinin-4 level in the brain and hemolymph that itself led to decreasing ecdysteroid titer in the ovary and hemolymph. finally the decrease in ecdysteroid titer resulted in smaller oocytes.