Chilli thrips Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) population phenology and spatial distribution in citrus screenhouse production systems

Chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), is an invasive polyphagous pest that can cause direct and indirect damage to various crops, and it has recently become an issue in CUPS (Citrus Under Protective Screen). This study aims to determine (1) the seasonal phenology of chilli thrips in this production system, and (2) the spatial distribution of chilli thrips in these systems. The present study examined the seasonal abundance of chilli thrips in citrus under protective cover at 3 different sites from February 2022 to February 2023. To monitor the chilli thrips population, the study evaluated three different methods. This included alcohol washes, yellow sticky cards, and tap counts. Results from the first year showed that chilli thrips density increases during late March and early April, as well as September. The number of adult thrips found early in spring captured by sticky cards was significantly higher than the number of thrips observed through alcohol washes. 

To date, the spatial distribution study has shown that chilli thrips has clumped distribution on CUPS, and the population of adult chilli thrips along the edges of the screenhouses was significantly higher than in the center of CUPS. Further research will elucidate if this is due to migration into the screenhouse.

The knowledge generated from this study will enable citrus growers to manage chilli thrips in CUPS in the future with greater accuracy. This understanding is crucial for developing an effective management program.