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Trichogramma
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Trichogramma |
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Trichogramma Wasp - a beneficial insect for the control of armyworms, cutworms, cabbage loopers, codling moth, leaf rollers and more
General information on the Trichogramma wasp, a widely used beneficial insectControlling insects biologically is challenging because it requires certain detailed knowledge of the target pest, frequent monitoring of the pest populations (every 2-3 days), and anticipatory strategies. In other words, with agricultural chemicals, it is often an instant cure whereas to rely on biological controls alone one must think ahead. One must recognize and/or anticipate a threatening pest population buildup... although that requires recognizing what a threatening situation IS (or could be). Plants can tolerate some pests and the economic threshold should be a consideration. In other words, the dollar gain should exceed the dollar cost (for controls). However it is important not to let the population of injurious pests get out of hand. First, once it does, irreversible damage has probably already occurred for which not even pesticides can rectify and, secondly, beneficial insects cannot control a huge population of injurious pests... they would be overwhelmed. The safe bet is to assume certain pests will be there (you must determine which) and have their natural enemies already at work keeping the pests at bay. Yet, timing the release of predators is extremely important and utilizing methods to keep them from straying off... a common problem (especially with ladybugs). Learning how to effectively control insects biologically takes time however, several seasons for sure... and experience is the key to success. While a challenging affair, it is more-so a noble battle, and for the determined (those who persevere)... victory is sweet. A.O. Kime - former Arizona and California agricultural Pest Control Advisor (1970-1992) and family farmer (1973-1998) TRICHOGRAMMA - ONE OF THE 'BIG FOUR' BENEFICIAL PREDATORSWhile there are dozens of beneficial insect predators, most have limited
applications, but four predators stand out as having a
multitude of applications. So for the time being, we are providing information
only on those four. Click any of the links below for information on the other three... ------------------------------------------
Trichogramma wasps(trichogramma pretiosum) < adult stinging a moth egg These extremely tiny wasps (also called 'minute' Trichogramma wasps) will sting a variety of moth eggs to deposit their own eggs and, as a result of the wasps hatching instead, the pest embryos are destroyed. While the moth itself is not destructive, it is the next (and last) metamorphic stage following their caterpillar stage, which is destructive. Within 10 days, an adult Trichogramma wasp will emerge but it will only live for about 14 days... which is one of several factors to consider when timing their release. Of the 145 described species worldwide, nine species of Trichogramma wasps are reared commercially or in government-owned facilities around the world which are released on an estimated 80 million crop acres annually. Former USSR countries, China and Mexico lead in the production of Trichogramma wasps. The species most commonly found within crops and orchards are atopovirilia, brevicapillum, deion, exiguum, fuentesi, minutum, nubilale, platneri, pretiosum, and thalense. While most releases of this wasp have been for the purpose of controlling the European corn borer, cotton bollworm and sugarcane borers, they have also been purposed to control some 25 other species of caterpillars including armyworms, cutworms, cabbage loopers, codling moth, leaf rollers, corn earworms, cotton budworms and tomato hornworms. These pests threaten vegetables, fruit trees, sugar beets, corn, rice, sugarcane, cotton, pine trees and spruce. Many crops are threatened by several of these pests simultaneously. However with the success of bacillus thuringiensis (a bacteria) in controlling cabbage loopers in lettuce, the wasp is seldom used for that purpose anymore. In sheer numbers, this tiny beneficial wasp is the most widely-used (worldwide) of all beneficial insects and its commercial usage dates back to the 19th century. Studies and field tests to find ways to improve the wasp's effectiveness and to expand its usage have been ongoing for over a hundred years. Because the Trichogramma wasp held so much promise initially, it has been studied and field-tested more than any other beneficial insect. At first, it was expected Trichogramma wasps would be the ultimate remedy for a variety of pest problems, but problems were encountered. The various conditions in the field, be it predators, temperatures or pesticide residues, were not always favorable for a release of the wasps. Yet, with only a 2-3 day window for optimum release, to delay a release often means NO control for pest control programs relying solely on biological controls. While regular releases can be more effective, which helps insure an adequate population of Trichogramma, to use that method one must weigh the costs. Recommendations may call for between 40,000 to 200,000 wasps (commercially delivered within parasitized host eggs) applied per acre weekly for 2-6 weeks to coincide with the heaviest moth egg-laying periods. For smaller plots, 12,000 per 500 sq. ft. Summary: Lifecycle: From egg to emergence is about 10 days. Effectively hatched full-grown, Trichogramma will only live for about 14 days. Positive points:
Negative points:
Since pest control results after releasing Trichogramma wasps have been reported to be inconsistent, varying considerably (it is said), its place as part of an integrated pest management (IPM) program would logically be questioned. Yet, in theory, the results should be consistently positive... perhaps thwarted only by the characteristics of the wasp which poses problems in managing their use. Their tiny size (3-4 can fit on the head of a pin) makes them vulnerable to other predators and the timing of their release must nearly be perfect. Compounding these problems is the short lifespan of a Trichogramma wasp (14 days). Further, the slightest amount of active pesticide residue is often fatally toxic... and IPM programs also incorporate the use of pesticides. However, intimate knowledge of the field situation, experience and a well thought-out plan should, more times than not, overcome most of these problems. Actually, poor results and the resulting 'bad press' is curious... Trichogramma being released on 80,000,000 acres (annually) says the results must be mostly positive. Are these inconsistent results confined to the USA? Perhaps the Asians and Mexicans are using a better system? Perhaps this might explain it... I hold the belief (although with only scant evidence) that Asian and Mexican farmers rely more on biological controls, and in many cases, rely entirely on biological controls. Considering the cost of pesticides and the application equipment required, this may often leave poor farmers little choice in the matter. If this is generally true, they would therefore use Trichogramma wasps every year regardless. And there are many more than 80 million acres being farmed by poor farmers worldwide (in just America alone, there are nearly one billion farmland acres). On the other hand, American farmers have choices... plus the results of pesticide usage to compare with Trichogramma results... hence the 'bad press'. Yet, I believe, success depends on the individual. It takes much more attention to detail than perhaps most American farmers find tasteful (acceptable). Further, field trials conducted by scientists, who are non-farmers, will invariably show poor results even in the best of conditions. As farmers, they're hopeless cases. Credits: Clicking on any thumbnail image above will take you to the photograph source (another website). The 9th U.S. Circuit Court of Appeals has ruled that a thumbnail image is ‘fair use’ provided it contains a hyperlink to the webpage where the full-size photograph was obtained, Nonetheless, if any owner of the copyright objects to our usage, upon notification we will immediately withdraw the thumbnail image.
Flew a tiny wasp with a tongue-twisting name, he visited my garden for which I sought fame. While he saved my lettuce, tomatoes and corn, when his stinger broke he used a brown thorn. A.O. Kime
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