2012 Annual Report
1a.Objectives (from AD-416):
To develop and optimize a mass rearing system for Lygus (L.) lineolaris and L. hesperus, based on colloidal artificial diets and gelling materials for egg collection to produce sufficient adult insects to maintain a constant production of approximately 50,000 eggs per week at reasonable costs and the identification of biological proteins with potential utility in developing plants resistant to Lygus species.
1b.Approach (from AD-416):
Development of chemically defined colloidal artificial diets, designed to resemble different plant hosts, will involve detailed chemical analyses of the plants by High Performance Liquid Chromatography (HPLC), Gas Chromatography (GC), Mass Spectrometry (MS), and Spectrophotometry. Based on the analysis, chemically defined artificial diets will be prepared by ARS. L. lineolaris and L. hesperus fed on the artificial diet formulations will be evaluated against L. lineolaris and L. hesperus reared on natural food sources, under controlled environmental conditions. Artificial diet formulations will be evaluated by measure of comparison of biological parameters such as developmental time, survivorship, sex ratio, fecundity, egg viability and longevity. Once an acceptable, colloidal formulation is identified biological proteins provided by cooperator will be incorporated in the formulation. The formulation then provided as diet to L. lineolaris and L. Hesperus and evaluated for deleterious effects on insect survival. Additionally, these biological proteins will be incorporated into water retaining agents at different concentrations to determine repellency levels. Development of the artificial diet based mass rearing systems will involve the optimization of mass production, dispensing, and egg collection.
A colloidal formulation resembling cotton plants was developed and both species of Lygus have been successfully reared for more than 5 generations. Colloidal formulation above mentioned has been evaluated at our labs. At the moment, the cooperator continues evaluation of biological proteins. Substantial progress has been done on insect production. Eggs of both Lygus species are continually shipped on a weekly basis starting in July 2010.
Improvements have been done to the system to fill oviposition pouches. Plant bug eggs are obtained using pouches of Parafilm filled with a semisolid gel commercially named Gelcarin®. This substance requires to be maintained at a critical temperature to become liquid, but at the same time remain in liquid state without melting the Parafilm® pouch. If the temperature is too low, the Gelcarin® solidifies instantly. A water bath system was effective to maintain the critical temperature of Gelcarin® to be dispensed inside the Parafilm® pouches without melting them. A new Gelcarin® dispensing system using a temperature-controlled pump was constructed and tested; however, significant modifications are needed to make it practical.