Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2013
Publication Date: 1/1/2014
Citation: Kumar, V., Kakkar, G., Seal, D.R., McKenzie, C.L., Colee, J., Osborne, L. 2014. Temporal and spatial distribution of an invasive thrips species Scirtothrips dorsalis (Thysanoptera: Thripidae). Crop Protection. 55:80-90. Available: http://dx.doi.org/10.1016/j.cropro.2013.10/015. Interpretive Summary: In the United States, chilli thrips is a newly introduced pest species of various tropical and subtropical crops that poses a significant economic threat to U.S. agriculture and trade. Since its introduction into Florida in 2005, the pest dispersed rapidly across the state and is causing significant economic damage to horticultural and nursery production. The probability of dissemination of chilli thrips through state, regional and international trade of plant materials is high for all life stages. Within five years of the introduction of chilli thrips into the U. S., establishment has been confirmed in 30 counties of Florida and eight counties of Texas, with additional positive reports of the interception of this pest in Georgia, New York, Alabama, Louisiana and California. New information was obtained on the dispersion of this new pest in the region and its relative abundance over space and time. Populations of the thrips were found to follow an aggregated distribution under field conditions. In vertical distribution studies, high abundance of chilli thrips was reported on the host plants placed at the lowest height above ground. During two years of seasonal abundance studies, significantly high population of adults and larvae were reported in the months of July and August. Information on the temporal and spatial distribution patterns of chilli thrips could add a new dimension to the management of this pest.
Technical Abstract: Dispersion of a new invasive thrips species, chilli thrips Scirtothrips dorsalis Hood, was studied on three hosts, i.e., cotton (Gossypium hirsutum L.), peanut (Arachis hypogeal L.) and pepper (Capsicum annum L.) in the greenhouse and under field conditions in Homestead, Florida. The study of horizontal distribution showed that S. dorsalis have weak dispersal potential and aggregate in open areas. During the entire study period, thrips were found to move a maximum of 9 m from their reservoir population. In a vertical distribution study, a strong negative relationship was observed between thrips density and height, with significantly highest mean number of immature (33.6) and adults (13.8) reported on host plants placed at the lowest height (45.7 cm) above ground. During two years (2009-2010 and 2010-2011) of study, high abundance of thrips population was observed during May-October with the highest mean count during July and August in both years. Flight activity of adults was highest between 10:00-16:00 EST, during peak solar radiation (~337-653 w/m2). Results from this study will help growers and extension personnel predict and farm-scale distribution of S. dorsalis and efficiently monitor the pest for management before they become a serious problem for vegetable and ornamental industry in the United States.