Population dynamics of onion thrips (Thrips tabaci lindeman, Thysanoptera; Thripidae) and varietal response of onion cultivars against onion thrips

Abstract

Population dynamics of thrips was studied at three different dates of transplanting (12th Dec’ 2017, 22nd Dec’ 2017 and 12th Jan’ 2018) on the “Agrifound Light Red” onion variety. The highest population of nymphs and adults of thrips was recorded on 3rd DOT (270 ± 8.65) followed by 2nd DOT (164 ± 8.22) and 1st DOT (129 ± 8.22). The peak population was observed once in 1st transplanted onion (12th SMW) and twice in 2nd transplanted onion (12th and 14th) and 3rd transplanted onion (12th and 15th SMW). The population of T. tabaci was significant positively correlated with temperature in 1st and 2nd DOT and negatively in 3rd DOT due to extremely high temperature coupled with maturity of crop. Relative humidity, rainfall and wind velocity showed negative impact on T. tabaci population. Six varieties were selected to screen against T. tabaci population and they were grouped under four categories according to T. tabaci intensity per plant namely highly resistant ( 8.76 12.07 15.38 < 18.69) -Onion Rob & Deep SS-11. The bioagents observed in onion field during the investigation were Orius tantillus (Hemiptera), Brumoides suturalis (Coleoptera), Hoverfly (Diptera).