Lethal and sublethal effects of a chitin synthesis inhibitor, lufenuron, against Glyphodes pyloalis Walker (Lepidoptera: Pyralidae)

Abstract

Glyphodes pyloalis Walker is a serious pest of mulberry trees in Iran. In this study, lethal (LC50 = 19 ppm) and sublethal effects (LC10 = 3.74 and LC30 = 9.77 ppm) of lufenuron were evaluated against 4 th instar larvae of G. pyloalis. After treating the larvae at LC30 and LC50 level, most of them died during the molting process and only a few individuals developed to the 5 th larval instar. The highest rate of mortality was observed in 5 th larval (68.42%) and pre-pupal (59.57%) stages at LC50 concentration. Also, lufenuron caused an increase in larval, pre-pupal and pupal developmental periods. The successful pupation decreased to 53.64% at the LC30. Also, no prepupa molted to pupation after treatment of larvae at the LC50. Larval weight was significantly reduced at 48, 72 and 96 h after treatment, compared to the control. Adult emergence and female longevity were also reduced at LC30. The LC30 of lufenuron negatively affected reproduction of G. pyloalis. Larval content of carbohydrate and protein were decreased significantly 48 and 72 h after treatment, however, lipid and glycogen content were decreased significantly only 72 h after treatment at LC10, LC30 or LC50. Findings indicated adverse effects on some biological and biochemical parameters at lethal and sublethal concentrations of lufenuron which necessitate further investigations for its application in an integrated management of G. pyloalis.