Comparative biology and morphometrics of pink bollworm, Pectinophora gossypiella (Saunders) on Bt cotton and alternate malvaceous hosts - Scientific Reports

The comparative biology of pink bollworm (PBW) on Bt cotton bolls and fruit pods of malvaceous plants viz., Abutilon indicum, Abutilon hirtum and Abelmoschous ficulneus was investigated under controlled conditions. The incubation time of PBW eggs from different hosts ranged from 2.0 to 4.5 days, which was not differ significantly among treatments. The mean larval duration of all four instars as well as average larval duration of pink bollworm reared on Bt cotton was more as compared to the larvae reared on A. indicum, A. hirtum and A. ficulneus. The average male and female pupal period were longer on Bt cotton. Both adult male and female from Bt cotton lived longer as compared to adults from A. indicum, A. hirtum and A. ficulneus. The weight of the different life stages of the pink bollworm was also more significant when reared on Bt cotton. Similarly, morphometric parameters, including larval body length and width, as well as pupal size and adult body dimensions (including wing expanse), were significantly greater in PBW reared on Bt cotton than on other hosts. Larvae feeding on Bt cotton undergo physiological stress that delays development but allows extended feeding and compensatory growth, resulting in higher weight and longevity. Thus, Bt cotton induces delayed development in Bt tolerant populations, while non-cotton malvaceous hosts support faster but nutritionally inferior development. Thus, the results clearly indicate that the pink bollworm completes its life cycle on malvaceous hosts and this also might be a reason for the off seasonal survival of pink bollworm in cotton growing regions. This study could have implications for crop management strategies for controlling the pink bollworm, that can cause significant damage to cotton crops.