Release of Ceranisus menes as a Biological Control Agent Against Thrips tabaci on Tomato (Solanum lycopersicum) Under Net House Conditions

Abstract

Onion thrips (Thrips tabaci Lindeman) are one of the main pests of tomatoes grown around the world. Adult and nymph life stages of this pest feed on tomato foliage by chewing through foliage to their vascular areas, causing silvering, chlorosis, foliar curling, and reduced photosynthesis, along with stunted plant growth. These injuries cause significant yield losses. T. tabaci also transmits many economically important tospoviruses, which makes its management very difficult on both open field and protected agricultural crops. The use of synthetic insecticides has resulted in insecticide resistance, environmental degradation, and the resurgence of insect pest populations, as well as negative effects on beneficial arthropods. Because of these problems, biologically-based environmentally sustainable control methods have become increasingly important components of integrated pest management programmes. The purpose of this study was to evaluate the potential of Ceranisus menes, a larval endoparasitoid, as a biological control agent against T. tabaci in protected agriculture. Four replicate tomato microplots were created with a total of 60 to 120 T. tabaci plot, and C. menes were released at densities of 15, 20, 25, and 30 adults at each release in sequential releases. T. tabaci populations were monitored prior to each C. menes release and again after to assess the percentage reduction of T. tabaci detected following each release. The data showed a clear density-dependent suppression of T. tabaci, with the highest parasitoid release density resulting in the greatest reduction of T. tabaci over time. The data from the cumulative release densities indicated a 60% level of suppression of T. tabaci populations within the high-density release treatment, and moderate levels of significant T. tabaci suppression occurred with the two lower release densities. The results of this study clearly demonstrate that the use of repeated releases of C. menes will substantially suppress T. tabaci populations and keep T. tabaci population densities below economic thresholds of damage in managed agriculture. These results also indicate high potential for C. menes to be an effective replacement for synthetic chemical insecticides used in tomato production systems, which is a safe and environmentally friendly manner. The integration of C. menes into integrated pest management programmes will result in sustainable reductions in the dependence of herbicides on tomato production systems while conserving and improving the populations of beneficial insects and enhancing the ecological sustainability of tomato production systems.