Evaluation of morphometric characters of chilli thrips, Scirtothrips dorsalis (Thysanoptera: Thripidae), pertaining to different geographical regions of world

Chilli thrips is a newly introduced pest in Florida and is dispersing quickly all over the state. It is a potential threat to our fruit, ornamental and vegetable industries. It has tremendous potentiality to spread at least 6 viral diseases to its host plants. This insect has been predicted to spread all over the United States causing an annual damage of more than $2.0 billion.Thus, the rapid and accurate identification of this exotic and potentially invasive taxa is essential to implement effective plant quarantine and biological control initiatives. If disregarded, it can cause severe economic losses or environmental damage. The small size and intraspecific morphological variations of chilli thrips make the detection and differentiation from other thrips not only difficult but basically impossible for non-experts. Considering this, we report certain morphometric characteristics of S. dorsalis which may facilitate its identification. Samples of S. dorsalis have been collected from 5 different geographical regions of the world, namely India, Israel, Japan, St. Vincent and Florida. Sizes of various body segments of S. dorsalis collected from aforementioned regions were measured and compared. Considering the effect of diet on morphometric characters, we found no significant difference in size of adult fed on different hosts. The study of putative origin of Florida population and establishing relation among these 5 populations of S. dorsalis using molecular techniques is under progress.