Aphidoletes aphidimyza, the aphid midge, is an aphid predatory midge that’s effective for the infestation management and control of several aphid species. The predacious larvae of these delicate, 3 mm. mosquito-like midges are best used for controlling substantial populations of more than 60 species of aphids including those mentioned for the Aphidius spp. — and, if timed correctly, the hemlock woolly adelgid (Adelges tsuga) as well. If established, they can adequately protect a crop from aphids throughout the season.
A. aphidimyza adults are very nomadic — traveling to where the action is — decimating populations of even some obscure aphid species. The midges are shipped as puparia (the last immature stage) in a vermiculite medium. The tubs they are normally shipped in serve well as emergence units.
The A. aphidimyza female adults, being nomadic, as mentioned above, actively seek out colonizations of aphids. Mated females, when they find these groupings, will lay eggs amongst the aphids — up to 250 of them. The eggs hatch into orange larvae which grow to 3 mm. These larvae kill aphids by injecting a toxin through their legs. They then eat the aphids or move on. Either way, the aphids die. Doing this, A. aphidimyza can destroy up to 50 aphids per day! The life-span of these predators is roughly 4 weeks in their immature stages, then less than 2 weeks as adults. The conditions for optimum performance will be between 64-77°F with a relative humidity of around 70%. But these are optimum conditions and not necessarily a prerequisite of successful implementation. Please note, however, significantly cooler or warmer temperatures and humidity fluctuations may hamper reproduction and development a certain degree.
If released into high infestations, A. aphidimyza larvae tend to kill much more than they’ll eat. This makes them capable of handling heavy pest pressure. These midges are extremely versatile; they are successfully used in many environments, including street trees, orchards, interiors, etc. They’re able to search in very high places. One contact successfully used them in 60 foot pecan trees in south-central Texas.
A. aphidimyza undergoes diapause (a quiescent state, hibernation) when temperatures dip below 40°F for extended periods or the photoperiod is less than 12 hours (D). Another drawback with this predator is the difficulty in finding it (see Scouting). Additional consideration should be given if pesticides are part of your IPM program; these midges are very sensitive.
These predators are hard to scout. The best thing to look for is adult presence. They may be seen during overcast weather or in the evening flying. Sometimes you can glimpse their mating dance, in which great numbers will be hovering in a tight cloud of bodies. This cloud will appear to be suspended in midair. The larvae may be seen at times. Since they are orange, they do contrast quite well with most foliage. Another sign of their activity is the high numbers of decimated aphids which can be left in their wake, plus a reduction of live aphids.
To counteract the natural urge for these predators to undergo diapause you must 1) keep the temperature above 40°F and, 2) provide supplemental lighting during the appropriate time of year. A 60 watt bulb for every 60 foot radius will do the trick. Bear in mind, however, most organisms, regardless of nature, will normally slow down a degree in the winter months. Ants, if present, should be controlled with something like boric acid. They will defend aphids from predators and parasites to protect their honeydew food (as it is with the Aphidius spp.). And this is very critical with A. aphidimyza. But at least heavy honeydew doesn’t bother these predators as much as it does with others. In fact, the adult midges will sometimes feed on the ‘dew themselves.
A. aphidimyza’s larvae drop to the ground or medium to pupate. And because of this your site must be adequate to provide for that activity: It must have a friable medium, or something that they can enter, sod is okay. Moreover, it is advisable to not use these predators on lettuce as the larvae might possibly drop between the leaves when they pupate. Hydroponic systems might also be inappropriate for the same reason.
Additionally, it is probably a good idea to suspend the use of parasitic nematodes — they may attack some of the pupae. If you are going to use A. aphidimyza, first determine that your site can foster their reproductive habits. (Note: Try using Stratiolaelaps scimitus for fungus gnats instead.)
Greenhouses, street trees, fields, interiorscapes, orchards and gardens. We’ve seen the successful implementation of this species in just about every conceivable situation.
Release Rates for Aphidoletes aphidimyza
|Comments||Higher release rates will result in more rapid control. Regular releases are recommended for continuous control!
|With aphid colonies present||0.5 to 1 per square meter
Aphidoletes aphidimyza – aphid predator (1,000)
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