Effects of flufenoxuron on the male reproductive development of Spodoptera mauritia Boisduval (Lepidoptera: Noctuidae)

Abstract

The insecticide flufenoxuron, one of the insect growth regulators used in pest control, has been presented as a viable alternative against several insects and mites by inhibiting chitin synthesis and leading to changes in the midgut epithelium. The current study aimed to examine whether flufenoxuron interferes with the structural organisation, weight, volume, fecundity and fertility of the male reproductive system of Spodoptera mauritia, a sporadic pest that occasionally inflicts significant losses to rice crops. Median effective dose (ED₅₀) indicates that flufenoxuron is effective against S. mauritia, and the moulting inhibition percentage, when calculated with probit analysis, indicates that ED₅₀ were 0.00068 µg for 144 h. Topical application of two selected doses (ED₂₅ and ED₅₀) was applied to find out the effects of flufenoxuron exposure on male gonadal development. The flufenoxuron treatment significantly impaired the organization and development of the testis follicles and other parameters like weight, volume and gonadosomatic index. Moreover, reductions in fecundity and fertility rate, 27.33 ± 13.86 and 85.36 ± 12 for treated male × untreated female, 47 ± 23.33 and 97.16 ± 22.92 for untreated male × treated female, and 4 ± 4 and zero for both treated pairs, were found in the emerged S. mauritia adult following the larval treatment, suggesting the occurrence of defects in reproductive organs in both male and female moths. These findings highlight the reproductive toxicity of flufenoxuron on the rice swarming caterpillar, offering insights into the male reproductive toxicity associated with chitin synthesis inhibition. The impairment of reproductive organ development suggests the potential use of flufenoxuron for controlling pest populations effectively.