Page Intro: Diglyphus isaea are warm-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 2 mm. mini-wasps, like D. siberica, 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 season.
D. isaea, which are shipped as pre-hatched, pre-fed adults, are the product of choice when leafminers are first seen, or soon expected to be seen, in a warmer area. They do best in warmer conditions.
Some of the several species which can be controlled with these parasitoids include the ones controlled by the preceding biocontrol agent. They can control 18 known species from four different genera, not just the genus Liriomyza.
Life-style
These parasitoids, work by “stinging” (oviposition) the larvae of leafminers while they work in their mesophyll mines (as described under Dacnusa siberica) with their ovipositors (egg-laying apparati). The stinging conveys a paralyzing toxin to the pests. The toxin works right away — the larvae stop feeding. But these mini-wasps don’t stop there. They will also feed on the hosts (host-feeding), as do many Chalcid (KAL-cid) wasps (a wasp family). They will then lay 1-5 eggs next to the paralyzed larvae — up to 50 eggs in their life. The wasps’ larvae which hatch from the eggs, then consume the leafminer larvae from the outside-in (ectoparasitism).
The parasitoids’ larvae then construct pillars of fecal matter around the remains of the much deteriorated pests. These are thought to protect the beneficial larvae from leaf drying, etc., while they undergo pupation.
The life-span of these parasitoids is roughly 2 weeks in their immature stages, then 3 weeks as adults. The conditions for optimum performance will be between 75-90°F with a relative humidity of around 80%. 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.
Benefits
The benefits are very much the same as those of Dacnusa siberica, with exception to the time of year for best use (spring and summer) and their temperature preferences.
D. isaea, also being shipped as adults, offer the benefit of fast oviposition or egg-laying.
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.
Drawbacks
The same drawbacks which plague the previously discussed parasitoid, hamper the use of this one too. This includes the price issue. But, as is the case with D. siberica, a little bit of D. isaea goes a long way.
Also, there can sometimes availability problems, so plan well ahead.
Scouting
Reduction of pest numbers is a sure sign of success. Or, if used preventively, a pest no-show. The scout can sometimes see the loose fecal matter on the leaves (cause by the paralyzation process), or the organized fecal matter in the form of pillars used for the pupal tombs.
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.
Usages
Greenhouses, fields, interiorscapes, orchards and gardens. These wasps are reportedly successful at nearly any site, ‘cept a really cool one!
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.
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. isaea. [Intro]
