Quality Assessment of Biological Control Agents
Friday, 26 March 2010 10:30
Just like you need to inspect incoming plants to assess their quality, it’s also important to inspect biological control agents as you receive them. Here are some tips for assessing the quality of the various types of natural enemies. Also, ask your biological control supplier on how to best evaluate any incoming shipments.
* Check number of shipment days and how cold or warm the ice packs are.
* Keep the package out of extremes of sun, heat or cold. Release as soon as possible.
* Predators and parasitoids that are shipped as mobile stages (predatory mites, some wasps) should be inspected upon arrival to determine if they are actively moving.
As an example, to assess the quality of predatory Mites such as Neoseiulus cucumeris or P. persimilis, spread a small sample of the mites on a white sheet of paper. Check with a 10 to 16x hand lens to make sure the predatory mites are active and moving rapidly. You should also check the rim of the container in which the predatory mites are shipped for the presence of live individuals. Shipments of N. cucumeris may also contain grain mites which serve as a food source. Grain mites are white, have long protruding hairs on their back and are generally less mobile than the tan-colored N. cucumeris.
Biological control agents shipped as eggs or pupae should be checked for viability by placing a small sample in a clear, airtight, dry container. Keep the container in a shaded, unsprayed area for two or three days, and carefully looking for the active larvae or adults.
Storage
Most natural enemies have a very short shelf-life, especially those that are shipped without a food source, and thus should be applied immediately. Natural enemies that are supplied with a food source can be stored for a few days before use; however, it is strongly recommended to use natural enemies immediately upon arrival. Storage time depends on the particular natural enemy and environmental conditions. If natural enemies must be stored, maintain them at 50-60ºF and 50-70% relative humidity. Do not place parasitoids or predators into refrigerators or in direct sunlight since refrigerator temperatures (35-45ºF) and exposure to sunlight are detrimental to both natural enemy types. In general, the longer that natural enemies are stored, the lower the survivability of the individuals. One common cause of natural enemy mortality during storage is desiccation, which may be avoided by placing containers of natural enemies in a plastic bag along with a moist sponge, and then securely sealing the bag.
From: New England Greenhouse Floriculture Recommendation Guide
For more information: Greenhouse IPM with an Emphasis on Biocontrol by Penn State University - Appendix D: Quick Methods for Evaluation Biocontrol Shipments. This is a overview chart of how to determine viability, and to determine establishment and reproductive success in the greenhouse for a number of biological control agents.
Also, check with your supplier for additional information.
Leanne Pundt, University of Connecticut
