In this third article in our series about using beneficials to solve challenges naturally and avoid harmful chemicals in the farm environment, we look at solutions for a common problem – bollworms. A bollworm is not a worm, but the larvae (caterpillars) of a number of different moth species. Voracious eaters, they do give farmers a real hard time.
The African bollworm, offspring of the moth, Helicoverpa armigera is considered a significant pest in southern Africa impacting on a wide variety of crops. While not really an issue in our vineyards, bollworms can present a challenge in our veggie gardens and orchards. There are many poisons available on the market to counteract bollworm but the creature has a strategy to counteract their effectiveness. The larvae embed themselves inside fruits or pods or bolls, in the case of cotton, which can protect them from toxins that are sprayed on the surface of crops. But effectiveness is not the only challenge. Many of the pesticides that have been routinely used have now been deemed unsafe to use on crops for consumption such as vegetables.
As a result, the control of bollworms through the use of beneficials; that is organisms rather than chemicals is starting to gain traction even in the mainstream. On farms, such as Avondale, where organic and biodynamic practices are favoured over conventional techniques that have harmful side-effects, we turn to Nature for the solutions to bollworm. There is a beneficial bacterium known as Bacillus Thuringiensis subspecies Kurstaki, and a virus, Helicoverpa armigera Nucleopolyhedrovirus (Granulovirus) that can help a farmer to effectively keep bollworm in check without creating any residual harm.
When the Granulovirus is sprayed onto the crops, the bollworm larvae ingest virus particles as they begin to eat. A protein lattice, known as an occlusion body, releases virus particles in the mid-gut of the larvae. The virus uses the larvae metabolism to replicate itself in the nucleus of the hosts’ cells so that it can invade all the tissue which results in death of the bollworm at no other cost.
This is another example of how using Nature’s own strategies can help farmers achieve their production goals without the use of harmful chemicals.