How often should the biopesticide be applied to the soil?
The frequency may depend on the economic impact of the pest or disease. If there is serious economic impact from the pest/disease, a weekly application is cost eﬀective and ensures persistence of high levels of the biopesticide where it is needed. At the other extreme, where the pest or disease is already reasonably under control – a monthly application may be suﬃcient.
How long will a biopesticide survive in the soil when drenched?
The soil is the natural habitat of a biopesticide and it may persist for several months, declining in concentration over this time because of strong competition from other microbes and soil insects that feed on fungi in the soil. However, the declining biopesticide microbe population in the soil may not provide as eﬀective crop protection against soil pests and diseases. So regular weekly applications may be necessary to provide the required level of crop protection.
How long will a biopesticide survive in the crop canopy when sprayed?
A biopesticide spray may not survive more than about 12 to 48 hours if it is exposed to the UV in sunlight in the canopy or very hot and dry conditions. However. If the spray comes into contact with the target pest and recognizes the host – it will germinate, penetrate and infect the inside of the pest, where it is immediately protected from the harmful eﬀects of challenging environmental conditions.
If the spray is directed eﬀectively to the under leaf surface on the lower part of the canopy the EPF can sometimes be seen growing on the pest cadaver (dead body). In the absence of the host, the EPF will not establish and grow on leaves.
What is the preferred prey of the diﬀerent Amblyseius spp?
Amblyseius cucumeris: Ist instar thrips juveniles and in the absence of thrips it will prey on spider mites and feed on pollen. Amblyseius swirski: Does best when both thrips and whiteﬂy are present at the same time but reproduces slowly if only one pest is present; Amblyseius californicus: spider mites in hotter dry conditions than Phytoseiulus prefers; Amblyseius montdorensis: preys well on spider mites, thrips and whiteﬂy but prefers higher humidity than A. californicus. Is the only Amblyseius to eat 2nd instar thrips and eats more whiteﬂy, thrips or spider mites per day than the other Amblyseius spp.
What is the risk of predatory mites moving out of the crop and eating other non-target insects or attacking the crop plants themselves?
There are no risks of this happening with the use of predatory mites produced by Real IPM. None of the predatory mites feed on plants. Phytoseiulus is very speciﬁc in the pest mites that it can feed on and will prey on other Phytoseiulus eggs and juveniles if spider mites are not available. Although Amblyseius spp can also feed on pollen, they cannot reproduce well without their preferred prey.
Does applying thousands of predatory mites into the ﬁeld – upset the balance of nature?
Planting all the same plant in one place (a crop) already upsets the ‘balance of nature’ and has attracted certain insects which feed on it and reproduce in it – upsetting the
‘balance of nature’ again. Using predatory mites in large numbers is necessary to regain control by eliminating the pest.
How can biopesticides help slow down resistance to chemical pesticides?
By tank mixing biopesticides with chemical pesticides, the farmer is in eﬀect designing a new ‘formulation’ of the chemical pesticide because of the addition of the many other modes of action supported by the biopesticide.
Can pests or diseases develop resistance to biopesticides?
Biopesticides diﬀer from chemical pesticides as far as ‘resistance management’ is concerned because beneﬁcial microbes have so many diﬀerent modes of action and produce a wide range of natural chemicals. Chemical pesticides are usually just one ‘active ingredient’, which makes it much easier for a pest or disease to develop resistance to this. There are no recorded incidences of resistance developing to a biopesticide – therefore they can be routinely sprayed and do not have to be ‘rotated’ with other active ingredients’ in the same way as it is necessary to rotate chemical active ingredient to avoid resistance.
How does resistance to chemical pesticides develop in pests and diseases?
Chemical pesticides generally only have one ‘active ingredient’. If the same chemical pesticide is applied too frequently – the pest or disease has the opportunity to develop ways to deactivate the pesticide’s chemical pathway. As the number of resistant pests and disease spores increase – resistance develops in a ﬁeld population.
See: www.frac.info and www.irac-online.org