Page Intro: Dacnusa siberica are cool-weather leafminer parasitoids. On this page you will find a description, life-cycle info, benefits, drawbacks, scouting info, advisories, usages, beyond the page, and other good stuff such as ordering.
Description
These 3 mm. mini-wasps are best used for preventing the establishment of several leafminer species. They can also tackle minor infestations. And, if established, they can adequately protect a crop throughout the (off-)season.
D. siberica, which are shipped as pre-emerged, pre-fed adults, are the product of choice when leafminers are first seen, or soon expected to be seen, in a cooler area. They do best in cooler conditions, as the species’ name implies: siberica, brrr!
Some of the several species which can be controlled with these parasitoids include the Florida, chrysanthemum or serpentine leafminer (Liriomyza.trifolii), the tomato leafminer (L. bryoniae) and many others of economic importance. [Intro]
Life-style
These parasitoids, work by laying eggs directly into the larvae of leafminers. And they can lay up to 72 eggs, killing a like number of the larvae. They do this while the larvae are working in their mines or tunnels. These mines are created as the larvae consume the leaf’s mesophyll (the cells which make the center of the leaf sandwich). The wasps’ larvae which emerge from the eggs, slowly weaken and kill the leafminer larvae from within (endoparasitism). New parasitoids exit the mines instead the fattened, full-term leafminer larvae, which usually drop to the ground to pupate (see Advisories).
The life-span of these parasitoids is roughly 2 weeks in their immature stages, then 1 week as adults. The conditions for optimum performance will be between 55-75°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 [colder] or warmer temperatures and humidity fluctuations may hamper reproduction and development a certain degree. [Intro]
Benefits
The life-cycle of these parasitoids is considerably shorter than that of their hosts. They can, therefore, overwhelm the pests in a matter of time with few, if any, other considerations. Patience is it. Under most conditions these mini-wasps will prosper and come out on top.
As described under Life-style, the tunneling which occurs is the damage of importance. It creates a visual eyesore. These parasitoids will help lessen the immediate damage, but they can’t reverse the damage — that’s why these wasps are a good late-winter/early-spring preventive. The main benefit, however, if used when leafminers are present, is to diminish the number of future pest generations.
If bad enough, the mines can become more than just a visual problem, they can hinder the plants’ photosynthesis. They can kill a plant! Therefore, ornamental crops are not the only applicable crops to use these on. Vegetables, too, are a candidate.
Dacnusa siberica are superb preventive agents, thus offering growers a potential money-saving tool. Additionally, they can establish themselves in nearly any situation. Unless things get too hot. (For warmer situations, see Diglyphus isaea, the warm-weather leafminer parasitoid). Once established, growers might be able to reduce the size of releases made due to the presence of on-site wasps: another money-saver.
D. siberica, being shipped as adults, offer the benefit of fast oviposition or egg-laying. And they can do this is in temperatures so low that many other biocontrol agents would stop in their tracks, shivering. [Intro]
Drawbacks
Despite the pages and pages of information I’m offering about this species of good critter, I know relatively little. My exposure to practical experiences is very limited. Try it with all of Europe’s widespread successes confidently behind you, but do so with the cautiousness and curiousness of a researcher.
These parasitoids are produced in Europe. This, among other things, adds to their expense. This drawback may disadvantage smaller growers (because a little bit goes a long way and minimums are not small). I am told that they are well worth the money, though.
These parasitoids are incapable of handling large infestations in an acceptable period of time; not cost-effectively, anyway. There can sometimes be rare availability problems from year to year, so plan well ahead. [Intro]
Scouting
Reduction of pest numbers is a sure sign of success. Or, if used preventively, a pest no-show.
The scout can sometimes also find adults on affected leaves. They’ll be seen tracing the mines with their antennae; this is how they find the location of their hosts. Exit holes may also be seen, but this extremely difficult to properly determine. [Intro]
Advisories
Yellow sticky traps may present a problem with these wasps. I am unsure of this and ask that you exercise cautious observation when the traps are in use. If parasitoid numbers on the traps get too high, remove the traps or use them for only two or three days per week.
As explained under Life-style, the leafminer larvae drop to the ground to pupate. And now for some good news: they can be parasitized by parasitic nematodes. [Intro]
Usages
Greenhouses, fields, interiorscapes, orchards and gardens. These wasps are reportedly successful at nearly any site, ‘cept a hot one! [Intro]
Beyond the Page
In greenhouses and other similar environments, it should be noted that supplemental control of leafminers can be realized with the use of parasitic nematodes. [Intro]
Rates, Instructions, and Purchase
Need more information? Check out our release rates or our short-term storage, handling, and release instructions. You may also purchase D. siberica. [Intro]
