Impact of weather on population dynamics and infestation of Leucinodes orbonalis Guenee on brinjal

Abstract

The purpose of this study was to determine the effect of weather parameters on the infestations of shoot and fruit caused by brinjal shoot and fruit borer (Leucinodes orbonalis) (Lepidoptera; Pyralidae) during Kharif and Rabi seasons of two consecutive years. The findings showed that the shoot infestation began (5.35%) in 1st week of January and severed (30.85%) in 3rd week of February and 1st week of March in the first and second years. The shoot infestation was associated positively (r=0.267) with temperature but negatively with relative humidity and rainfall (r=-0.182 and -0.235). The fruit infestation (26.57% and 21.74%) began in the 1st week of February and gradually peaked (52.69 and 46.36%) in the 1st week of March. However, it was associated negatively with relative humidity (r=-0.773 and 0.747) and rainfall (r=-0.204 and -0.202) while positively with temperature during the rabi season of the first year. The same patterns of infestations were recorded in the next year. Compared to the Kharif seasons, shoot infestation started (7.65%) in 1st week of July and the highest (31.21%) in 3rd week of August. Additionally,  it was associated negatively with temperature (r=-0.235) while positively with relative humidity  and rainfall (r=0.060 and 0.677). The infestation of the fruit started (27.35 and 21.25%) in 1st week of August and steadily increased, reaching to peak (53.26 and 47.22%) in 1st week of September. Moreover, it was associated negatively with temperature (r=-0.500 and -0483)  and positively with relative humidity (r=0.426 and 0.443). However, a negative association  (r=-0.187 and -0.180) was found with rainfall. While in the second year, the same infestation patterns were recorded as the previous year, except rainfall was positively (r=0.0283 and 0.287) associated with fruit infestation. In conclusion, the weather affects the BSFB infestation significantly or non-significantly. This finding could be helpful for farmers in planning their  cultivation practices for brinjal and pest management strategies to reduce the infestation caused by BSFB.