Trichogramma carverae

Chemicals and Trichogramma wasps

Introduction to chemicals
Key to toxicity ratings
Insecticides table
Other considerations
Fungicides table

Which chemicals can be used?

Many chemicals are hazardous to Trichogramma wasps. However, in recent times a number of "soft" biological and chemical insecticides have become available and these have made it easier to incorporate Trichogramma and other beneficial insects into IPM programs.

Although Trichogramma are sensitive to many chemcals they are often found in crops that have been sprayed with "hazardous" chemicals. How have they survived? Several factors are at work. Trichogramma spend much of their lifecycle developing inside the host egg and as such are protected to various degrees from chemical applications. Adult wasps may be killed by a spray but those developing in eggs may get through.

Also, spray penetration is rarely perfect - eggs under leaves and in crevices may not be covered by the chemical.

Although Trichogramma may survive in crops where broad spectrum chemicals are used, the use of "hazardous" products is undesirable if you wish to get the full benefit from the wasps.

The table below gives a guide to the effects of some products in use:

Key to toxicity ratings

Applied = toxicity of chemicals when sprayed on the beneficials in the field. The rating is a general overall toxicity allowing for the impact on the population of the beneficial.

Low toxicity = nil or low impact on beneficials.

Moderate toxicity = beneficial activity significantly reduced but can recover in a week or so.

High toxicity = a high proportion of the beneficial population is killed and re-establishment will not be possible for several weeks.

( ) = estimated toxicity, based on anecdotal information and known impact on similar organisms.

Residual = suggested waiting time after application of the product before introducing beneficials.

Insecticides - Check crop registrations before use
Product	Trade names	Toxicity to Trichogramma
		Applied	Residual*
Bt products	Dipel etc	nil	nil
NPV products	Gemstar, Vivus	nil	nil
Tebufenozide	Mimic	low	low
Fenoxycarb	Insegar	low	low
Methoxyfenoxide	Prodigy	very low	1 day
Indoxycarb	Steward, Avatar	low	3 days
Novaluron	Rimon	low	3 days
Diafenthiuron	Pegasus	low	3 days
Pyriproxifen	Admiral	low	3 days
Thiocloprid	Calypso	low	3 days
Abamectin	Agrimec	low to moderate	3 days
Emamectin	Affirm	low to moderate	3 days
Pymetrozine	Chess	low to moderate	3 days
Imidacloprid	Confidor	low to moderate	5 days
Fipronil	Regent	moderate	5 days
Spinosad	Tracer, Success	moderate to high	3 days
Pyrethroid, organophosphate and carbimate insecticides are generally "highly" or "very highly" toxic to Trichogramma and should be avoided if possible. Sulphur is also toxic to Trichogramma. Applications of these products will severely reduce Trichogramma numbers which may take several weeks to recover. Typically 7 to14 days needs to elapse after using these products before releasing Trichogramma. There are some differences within these groups and research is ongoing to identify those less toxic formulations.
* Estimated time to wait before releasing Trichogramma. These ratings relate to one spray. Repeated sprays are likely to result in an accumulation of residues. This is most significant in indoor conditions where it may take several months before residues have dispersed and establishment is possible.

Other considerations
If the number of larvae and/or unparasitised eggs exceeds your threshold and its deemed that a spray is necessary then use the softer options.

Be aware that the higher the number of parasitised eggs per hectare the more robust will be the wasp population and the quicker they will recover from spraying of a moderately hazardous product. Adult wasps may be killed but wasps developing inside eggs are protected to some degree.

Conversely, low numbers of hosts will only support a low population of wasps so using hazardous insecticides during such periods will severely effect wasp numbers and recovery may be slow.

See also Monitoring and Environment

Fungicides - Toxicity to Trichogramma
Disorder	Chemical	Trade Name	Toxicity to Trichs	Days to wait*
Powdery Mildew	Bitertanol	Baycor	low	2
	Benomyl	Benlate	low	2
	Bupirimate	Nimrod	low	2
	Fenarimol	Rubigan	low (?)	2
	Dimethirimol	Milcurb	low (?)	2
	Milk	-	low	2
	Thiophanate Methyl	Topsin	low	2
	Triadimefon	Bayleton	low	2
	Propiconazole	Tilt	low	2
	Penconazole	Topaz	low	2
	Triforine	Saprol	moderate	3
	Carbendazim	Spin	moderate	3
	Oxythioquinox	Morestan	moderate	5
	Wettable Sulphur	Various names	high	5
	Pyrazophos	Afugan, Curamil	high (?)	5
Downy Mildew	Copper Oxychloride	Various names	low	2
	Zineb	Zineb, Curit	low	2
	Metiram	Polyram	low	2
	Chlorothalonil	Bravo, Daconil	low	2
	Dithianon	Delan	low	2
	Propineb	Antracol	low	2
	Copper Oxy + Zineb	Zinox	low	2
	Mancozeb	Mancozeb, Dithane	low-moderate	3
Grey Mould	Iprodine	Rovral	low	2
	Dichlofluanid	Euparen	low (?)	2
	Vinclozolin	Ronalin	low	2
	Chlorothalonil	Bravo, Daconil	low	2
	Dicloran	Allisan	low	2
	Thiram	Thiram	low	2
Black Spot etc	All Copper type sprays		low	2
	Dichlofluanid	Euparen	low	2
	Benomyl	Benlate	low	2
	Bitertanol	Baycor	low	2
	Chlorothalonil	Bravo, Daconil	low	2
	Thiram	Thiram	low	2
	Ziram	Ziram, Fulisan	low	2
	Thiophanate Methyl	Topsin	low	2
	Metiram	Polyram	low	2
	Fenarimol	Rubigan	low	2
	Dodine	Dodine	low	2
	Dithianon	Delan	low	2
	Triforine	Saprol	moderate	5
	Mancozeb	Mancozeb,Dithane	low-moderate	3
* Days to wait after spraying before releasing Trichogramma. (?) Indicates that the rating is likely but not confirmed.
This Table is a GUIDE ONLY.
CHECK crop registrations before spraying.

Trichogramma carverae are produced by Bugs for Bugs

Sales enquiries contact BioResources Pty Ltd

Phone (07) 3289 4919 email: richard@bioresources.com.au