dr. bugs BY RAYMOND A. CLOYD Releasing Multiple Biological Control Agents Question: What are your thoughts about releasing more than one biological control agent to regulate an arthropod (insect and/or mite) pest population? Answer: You ask a very good question. To properly address the question, it is important to provide some introductory information. First, there are two types of biological control agents: specialists and generalists. Specialists attack or feed on one or only a few at most different arthropod pests. Generalists tend to attack or feed on several different arthropod pests. Furthermore, generalists will feed and reproduce on alternative food sources including pollen (as will some specialists). In general, parasitoids tend to be specialists, whereas predators tend to be generalists. An inadvertent effect of releasing different species of generalist predators in a biological control Raymond A. Cloyd Green lacewing larva. program is that the released predators may prey is professor and upon each other or another biological control agent; this that have been parasitized by the parasitoid, Leptomastix Extension specialist is called intraguild predation. dactylopii; and 4) the predatory mite, Amblyseius swirskii, will in horticultural Intraguild predation occurs when one biological control prey upon the larvae of the aphid predatory midge, Aphidoletes entomology/ agent feeds on another biological control agent. Consequently, aphidomyza, and will also feed on the eggs, larvae, and nymphs plant protection intraguild predation can negatively impact or disrupt biological of P. persmilis. at Kansas State control. There are numerous examples of intraguild predation The effect of intraguild predation, based on releasing University. He occurring under greenhouse conditions, including the following: multiple biological control agents, may be associated with the can be reached at 1) the predatory mite, [email protected]. formulation or how biological Neoseiulus californicus, will control agents are packaged. feed on another predatory For instance, ‘breeder piles’ mite, Phytoseiulus persimilis, Intraguild are small piles (1 to 3 grams) when the targeted pest is containing the predatory mite, absent, in this case, the predation occurs Neoseiulus cucumeris, and twospotted spider mite, bran mold mite, Tyrophagus Tetranychus urticae; 2) putrescentiae, that are adults of the predatory bug, when one biological placed on the surface of Orius majusculus, will feed the growing medium. These on sweet potato whitefly, control agent feeds breeder piles should not be Bemisia tabaci, nymphs that used in conjunction with the have been parasitized by the rove beetle, Dalotia (formally parasitoid, Encarsia formosa. on another biological Atheta) coriaria, because rove As a result, the interactions beetle adults and larvae feed between O. majusculus control agent. on predatory mites in the and E. formosa can disrupt breeder piles. biological control of the sweet It is important to note potato whitefly; 3) the "mealybug destroyer," Cryptolaemus that releasing multiple biological control agents does not montrouzieri, will feed on citrus mealybugs, Planococcus citri, always result in a disruption of biological control or intraguild 18 JANUARY 2021 GPNMAG.COM DR. BUGS BOOTH #0106 www.ipmlabs.com • 315 497 2063 [email protected] Mealybug destroyer (Cryptolaemus montrouzieri) adult. Biological controlsGreenhouse for Grower 2021 Aphids, Thrips, Fungus Gnats, APHID GUARDTM Spider Mites, Whiteflies and more… Banker Plant NEW! Predatory mite (Neoseiulus cucumeris). predation. For instance, greatly influence intraguild simultaneously releasing two predation. whitefly parasitoids; E. formosa Intraguild predation is an and E. pergandiella, and a interaction that occurs when predator, Delphastus pusillus multiple biological control agents (=catalinae), did not negatively are released simultaneously with affect regulation of silverleaf one of the biological control whitefly, Bemisia argentifolii, agent inducing mortality on populations. another biological control agent. Life stage may influence This can influence the success ALYSSUM (AURINIA) saxatile ’Gold Kobold’ intraguild predation because of biological control programs, individuals are typically more although this may not always the susceptible when small and/ case. Therefore, for a biological Exciting New Perennial or in certain life stages such control program to succeed, as eggs, larvae, nymphs, and/ it is critical to avoid releasing Varieties from Seed or pupae. For example, green multiple biological control agents lacewing, Chrysoperla carnea, or determine those biological www.jelitto.com larvae prey upon ladybird beetle, control agents that can be used Hippodamia convergens, larvae together to regulate arthropod and immatures of the parasitoid, pest populations without Aphidius smithi. Therefore, life resulting in reduced arthropod stage, which is associated with mortality caused by intraguild Production · Breeding · Seed Technology body size, is a factor that can predation. USA Office: 125 Chenoweth Ln. · Louisville, KY 40207 Phone (502) 895-08 07 · Fax (502) 895-39 34 · www.jelitto.com · [email protected] German Headquarters: P. O. Box 1264 · D-29685 Schwarmstedt Phone 01149-5071-98 29-0 · Fax 01149-50 71-98 29-27 · [email protected] .