Aphytis melinus, also known as “The Golden Chalcid,” is used to prevent and manage low-infestations of various armored scales. These yellow-gold, 1.2 mm. mini-wasps are best used to tackle and maintain minor to heavy infestations of several armored scale species. And, if established, they can adequately protect a planting for a season or, perhaps, more in certain situations.
A. melinus, which are shipped as pre-emerged adults, are the product of choice when armored scales that can host the Golden Chalcid (KAL-cid) are present. Armored scale insects do not produce honeydew and, therefore, the mini-wasps are not accustomed to it, even though these parasitoids are typically shipped with honey or a honeydew substitute, but this just satisfies their need for moisture.
Some of the species which can be controlled with these parasitoids include the California red (their favorite) and yellow scale insects (Aonidiella aurantii and A. citrina, respectively); the San Jose scale (Quadraspidiotus perniciosus); the ivy or oleander scale (Aspidiotus nerii); the oystershell scale (Lepidosaphes ulmi) and other economically important species including, as we discovered in 1997, the magnolia white scale (Pseudaulacaspis cockerelli).
These parasitoids, which find their hosts with their antennae or feelers, work by laying eggs underneath female scales which have loosened their position on the leaf to facilitate reproduction. They will lay up to 25 eggs, killing 5 to 25 pests as they go. They will feed on many more. The wasps’ larvae which hatch from the eggs, then methodically eat their way through the scales from the underside out through the back (ectoparasitism). New parasitoid(s) emerge out of the empty scale cadavers after they pupate. And they’re off again!
The life-span of these parasitoids is 18 days in their immature stages, then not quite a month as adults. The conditions for optimum performance will be between 76-85°F with relative humidity between 40-50%. 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.
They’re quite inexpensive and, if you’ve got the right host and conditions, they’re an incredible buy!
A. melinus are superb curative agents, thus offering growers a potential money-saving tool (they’re a lot more economical than pesticides). Additionally, they can establish themselves in nearly any situation. Once established, growers might be able to reduce the size of, or curtail, future releases due to the presence of on-site wasps; another potential money-saver.
Lastly, these parasitoids, being shipped as adults, offer the benefit of fast oviposition or egg-laying, plus a lot of host-feeding.
These mini-wasps have a low fecundity (egg-laying) rate, and they won’t overwinter in cold climates. Nevertheless, they do a good job, are supplied in a large quantities and are affordable.
Reduction of pest numbers (empty scales and lack of crawlers) is a sure sign of success. The scout can also usually find scale insect cadavers with an exit hole in them. This is a very positive sign. Trying to spot the wasps themselves, say, two weeks after a release, would be an exercise in futility.
If armored and soft scales are present together (soft scales being a honeydew producer), ants may be a problem with this parasitoid. They don’t seem to mind the sticky stuff themselves, though. Use barrier products or boric acid products to control the ants, if they are a problem.
Greenhouses and interiorscapes are the settings where these parasitoids are most often employed. However, in the right environment, these wasps can be used with great success outdoors. After all, they are reared especially for the California citrus industry.
Release Rates for Aphytis melinus
|Preventative||1-3/square feet, monthly, as needed|
|Low to medium infestations||3-6/square feet, bi-weekly, as needed|