Population Dynamics in Groundnut and their Relationship to the Weather Parameters

Background: Groundnut crop is the most commonly, and widely grown oil seed crop during the Rabi season at Nagarkurnool district of Telangana state. However, insect pests viz., leaf miner (Aproerima modicella), tobacco caterpillar (Spodoptera litura Fab.), thrips (Scritothrips dorsalis) and jassids (Empoasca kerri Pruthi) are the major insect pests accounting major yield losses. The sowing window of the crop during rabi starts from 1st Fortnight of September to 1st FN of November. The insect pest’s incidence on different dates of sowings varied and ultimately reflecting the final yields under farmer fields. By keeping this in view to suggest a best sowing window where the crop would be less effect by the pests with estimated yields, a study has been taken up to observe the best sowing window where the final yields would be less affected by the pests and diseases.

Methods: The population dynamics of major insect pests of groundnut were investigated in five different dates of sowings at the Regional Agricultural Research Station, Palem (PJTSAU), Nagarkurnool District, Telangana, during rabi, 2019-2021. During the study, the major insect pests viz., leaf miner, tobacco caterpillar, thrips, and leafhoppers were observed in all the sowing windows.

Results: The Spodoptera litura population initially appeared during 38th SMW. Among all the sowings, the highest infestation occurred in D3 (41.23%) during 48th SMW. Leaf miner incidence was confined to early stage of the crop which was started at 38th SMW and highest incidence of 5.0 webs/plt during 41st SMW in the D1. The maximum leafhoppers population was noticed at D4 (7.2 leafhoppers/plt) and D5 (7.3 leafhoppers/plt) during 50th and 51st SMW. While the highest thrips damage occurred in D3 (3.4 thrips damaged plt/5 plts) at 47th SMW. S. litura, leaf miner, and thrips showed a positive correlation with TmaxºC, TminºC, RH-I%, and RH-II% during D1 while the leafhoppers exhibited a positive association with Tmax°C, Tmin°C, RH-I% and a negative correlation with RH-II%. Overall, the study revealed that the D2 was the optimal sowing window with the lowest insect pest population and damage caused by them, while D3 showed the highest pest population among all the sowings.