AVERMECTINS: EFFECT OF SUBLETHAL DOSES ON OOCYTE DEGENERATION IN FEMALE CADRA CAUTELLA WALKER¹ (LEPIDOPTERA: PYRALIDAE)

Oocyte degeneration in Cadra cautella was reduced by 40 to 70% following injection with sublethal doses of avermectin B₁a and ivermectin. When the reproductive tract was dissected following treatment with avermectin, however, muscular contractions of the bulla seminalis were visually unaffected. This suggests that the inhibition of oocyte degeneration occurs not in the bulla seminalis, the site of oocyte degeneration, but elsewhere in the reproductive system, possibly in the ovaries or the oviducts. The differential response of the organs in the reproductive tract suggests that these organs may have potential in evaluating toxins affecting the visceral muscles.