Location: Biological Control of Pests Research2012 Annual Report
1a. Objectives (from AD-416):
The long-term objective of this project is to develop an improved understanding of the biology, nutrition, and behavior of natural enemies of pest arthropods. Our primary target pest will be the two-spotted spider mite, Tetranychus urticae. Some of the most important natural enemies of this mite are phytoseiid predatory mites and coccinellids. We aim to implement, improve and increase the mass rearing capabilities of these organisms by developing artificial diets and novel rearing technology to enable economical biological control of this pest by augmentation of its natural enemies and to develop novel techniques of quality control and quality assurance. Our work will focus on the following: (1) Determine nutritional, behavioral, and physical conditions necessary for in vivo and in vitro insect rearing and use the results to implement mass production systems of biological control agents. (2) Determine the impact of mass rearing procedures on survival, reproduction, and gene expression. (3) Assess optimal conditioning of insects for release.
1b. Approach (from AD-416):
Research activities will focus on a specific predator, Stethorus punctillum and a generalistic predator, Coleomegilla (C.) maculata. Studying the nutritional requirements of a generalist versus a specific predator will provide insights on diet development of these 2 organisms. The generalist predator is expected to be an easier target for artificial diet development and success will have greater impact since C. maculate is an important predator of several economically damaging pest species.
3. Progress Report:
Three artificial diet formulations have been developed for the pink spotted lady beetle, Coleomegilla (C.) maculata. Full diet evaluation and comparison to a control consisting of bee pollen and Ephestia kuehniella eggs (1:1) is underway and expected to be completed before the end of the fiscal year. Lady beetles have completed development and reproduced in each of the 3 diet formulations. Three new cage designs have been introduced to improve C. maculata rearing. One of the designs improves egg collection and reduces egg cannibalism; the second design allows immature rearing in large groups using artificial diet, reducing cannibalism; in the third design, large numbers of eggs are collected from hundreds of adults fed with artificial diet where oviposition and feeding areas are divided to prevent cannibalism. Temperature dependent development studies of C. maculata at 3ºC intervals are under way and expected to be completed before the end of September. Studies on the life history of the pink spotted lady beetle revealed that this predator readily consumes all life stages of the two-spotted spider mite (Tetranychus (T.) urticae) in rearing systems under development. Plans are underway to test the foraging rate of predators (searching for spider mites) on live plants in rearing rooms and a greenhouse. A highly inbred colony with wild type phenotype was selected from the stock colony and a yellow color morph was obtained by laboratory inbreeding. A colony is currently under selection for a lighter red/gold phenotype. Olfactometer studies demonstrated that the plant-derived molecule methyl salicylate was attractive to C. maculata adults but did not stimulate egg production or feeding. Ongoing research is examining other molecules for their potential as oviposition and/or feeding stimulants. Experiments are in progress to define the influence of extreme temperature and humidity that predators (C. maculata) endure while transported from commercial producers to end-users (farmers, growers). Preliminary observations done with mini loggers indicate that temperatures fluctuate widely during transport. These fluctuations have negative consequences on the fecundity (reproduction) of predators at the point of release for augmentative biological control. In the in-vivo rearing of nematodes, diets containing 0.15% manganese and 0.16% cholesterol fed to yellow mealworms improved virulence in one nematode species. A multiple-choice study using 7 diet ingredients resulted in a better diet for the yellow mealworm using self-selection to adjust ingredient ratios. Successful production of the spined soldier bug (Podisus maculiventris) eggs allowed continuous culture of 4 imported and 4 native egg parasitoid species being evaluated for application against 3 exotic invasive insects: The brown marmorated stink bug, the bagrada bug and the kudzu bug.
Riddick, E.W., Rojas, M.G., Wu, Z. 2011. Lima bean lady beetle interactions: spider mite mediates sublethal effects of its host plant on growth and development of its predator. Arthropod-Plant Interactions. 5(4):287-296.