Liriomyza (Diptera: Agromyzidae) leafminer and parasitoid species composition on pepper and effects by selected insecticides in south Texas

Liriomyza (Diptera: Agromyzidae) leafminer and parasitoid species composition on pepper and effects by selected insecticides in south Texas.

In South Texas dipterous leafminers are increasing in numbers reaching pest status in some vegetable crops, and the application of insecticides as the sole pest-management strategy is failing. Conservation biological control can be used to help in the control of the pest by incorporating the use of insecticides that seclude natural enemies. In order to develop such program it is necessary to define which Liriomyza species are causing the outbreaks and which parasitoid species are contributing to the mortality of the pest. During the fall 2007 and spring 2008, four insecticides (abamectin, novaluron, spinetoram, and lambda-cyhalothrin) were applied on peppers. Random collected leaves and plant phenology were used to monitor insecticide efficacy, and infested leaves were also collected to monitor insecticide effects on parasitoids species. In addition, an intensive survey of leafminer and parasitoid species composition was performed throughout the Lower Rio Grande Valley (LRGV) of Texas to determined leafminer species and parasitoid guilds present in this area. The data shows differences in efficacy among the four insecticides; lambda-cyhalothrin is the least efficient and novaluron shows the greatest efficacy. Insecticide effects on parasitoids varied among treatments. Parasitoid survey shows species from four different families, and some of them have not previously been recorded on LRGV area, such as: Opius browsvillensis, Opius thoracoseiia (Braconidae), Ganaspidium pusillae Weld, Ganaspidium nigrimanus Kieffer, Agrostocynips robusta Ashmead, Disorygma pacifica Yoshimoto (Figitidae) and Heteroschema (Pteromelidae) among others.