Melittobia acasta
Pest description These small, dark brown wasps (adults 1 to 1.5 mm) are generalist idiobiont ectoparasites that develop gregariously and is an occasional pest in managed stock of leafcutting bees. One or several female adults chew through bee cocoons and once inside they sting and paralyze the larva, then feed on the hemolymph from the wound and lay clutches of 4 to 12 eggs. Eggs are initially laid on the ventral side of the host and take from 15 to 28 days to develop through four instars. Several hundred progeny may be produced over multiple successive generations each year. Females prefer to oviposit when the BOB are in pre-pupa or pupa stages, and are attracted to cocoon volatiles, frass and acetic acid.
Management Use of traps when rearing alfalfa leafcutting bees is recommended from May to November to attract and control parasites that emerge from nests returning from the field. Plastic strips coated with Dichlorvos is an effective trap in climate-controlled rooms. Parasites directly exposed to strip die within 2 hours, or 7 to 8 hours if buffered by a cocoon. The strips should be used as soon as the first parasites emerge, but with great care as to not expose the bee for a prolonged amount of time. No predators upon Melttobia have been recorded.
For more information:
A.R. Anderson, R.A. Ramirez, J.E. Creech, T.L. Pitts-Singer. 2023. Melittobia acasta (Hymenoptera: Eulophidae) female longevity and life stage-dependent parasitism using commercially managed Megachile rotundata (Hymenoptera: Megachilidae) as hosts. J Ins. Sci.3: 1-8.
A.R. Anderson, R.A. Ramirez, J.E. Creech, T.L. Pitts-Singer. 2023. Life cycle of Melittobia acasta (Hymenoptera: Eulophidae) using Megachile rotundata (Hymenoptera: Megachilidae) as a host. Ann. Entomol. Soc.Am. 116: 207-218.
De Wael, L., M. De Greef and O. Van Laere.1995. Biology and control of Melittobia acasta. Bee World, 76(2): 72-76.