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Using Melittobia australica

In many geographical regions of the world, the original WOWBug, Melittobia digitata, does not occur. However, the genus Melittobia is widespread. One of the most common species, particularly in the Southern Hemisphere, is Melittobia australica. With slight modification, it is completely suitable for use with the educational materials developed for M. digitata.

The key to successful classroom use of M. australica lies in knowing that females have three developmental forms that both look and behave differently from each other (Dahms, 1984; Freeman and Ittyeipe, 1993). Within a single set of offspring, one finds:

• Walkers: First to emerge are short-winged, stout-bodied females that do not fly. They simply crawl slowly around on the host. Within hours after mating, they lay eggs on any host remains that were not used for their own larval feeding. In nature, walkers probably never leave the host cocoon.
• Jumpers: Next to emerge are short-winged females that hop rather than crawling or flying. Instead of laying eggs on the unused host material, they hop about the vicinity of the nest looking for new larvae or pupae to attack. Jumpers readily hop toward light.
• Fliers: Last to emerge but comprising most of the offspring, fliers look like normal miniature wasps, with wings that nearly reach the tips of their abdomens. After mating, they become avid chewers that are strongly attracted to light . Given the chance, they escape in large numbers, seeking new nests to attack.

Because adults live for approximately two weeks, at different time intervals the population will contain varying proportions of these overlapping lives. During the first week of emergence, most of the females that are present will be walkers. During the second week, most will be fliers.

The early-emerging walkers are easiest to handle in the biology classroom. Therefore, whenever possible, use the first 50-100 wasps to emerge from your culture, which will almost certainly be young female walkers.

Walkers and jumpers do not usually fly, but when released they scatter. To round them up, place a small vial over one. It will crawl upward into the closed end. Repeat this until you have captured them all. Then tightly close the vial with a cotton plug.

Because of their attraction to light, the late-emerging jumpers and fliers are more difficult to control.

Some experiments in WOWBugs: New Life for Life Science. yield more dramatic results with one form than with another. However, with a little experimentation, this diversity can be a bonus for teachers and students. The walkers ensure easy handling for beginners, while advanced students can compare and contrast the behavior of forms of a single species, adding new richness to the activities as originally presented.

Tips for Rearing Melittobia australica

Like its other Melittobia relatives, M. australica can be obtained from natural infestations. Laboratory rearing is simple and follows the same general procedure as for the WOWBug; also see the "WOWBug Rearing and Maintenance" film.

Females of all three forms of M. australica are equally suitable for starting cultures. However, the short-winged walkers are easiest to handle, and will lay eggs almost immediately. The flyers will not begin to oviposit on the host for a few to several days after mating.

Like the larvae of other Melittobia species, the immature stages of M. australica are quite accepting of various hosts under laboratory conditions. They can generally be maintained on any of several artificial hosts, including social bee or wasp larvae and the puparia of some species of flies.

If natural hosts are in short supply and you wish to maintain an ongoing culture, we recommend rearing them on blowflies available from Carolina Biological Supply. However, if you wish for students to view all stages of the Melittobia life cycle, it is important to use a "naked" host (i.e., one that is not covered by a cocoon or puparium). Thus, the larvae or pupae of any bee or wasp are worth trying.