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May 2017. Members suggested various IPM approaches to the fall armyworm on maize to control the recent widespread infestations across Africa. From Henry Murillo:
The best option for now is to develop IPM with minimal use of strong pesticides like pyrethroids, organophospates, etc that will wipe out natural enemies. The best option for now is to develop conservation management and see what natural enemies like chrysopids, coccinellidae and parasitoids can do. I have been working with S. frugiperda in Colombia, Canada, USA and Puerto rico and if strong chemicals are not used, predators and parasitoids do very well. For example, in America from Argentina to Canada, besides many others Chrysoperla, Coleomegilla maculata and Campoletis are found predating/parasitizing S. frugiperda everywhere. I know there is at least one species of Campoletis parasiting S. exempta in Africa that I am pretty sure will move to S. frugiperda. In Colombia and Canada, corn growers spray 2-4 times per crop and in Puerto Rico and Florida (USA) growers spray 2-4 times per week (I don’t barbeque sweet corn anymore since I live in Florida).
Finally, I will second Ernst on Telenomus remus, which has been introduced from east Asia with great success in many countries (India, Israel, Caribbean islands, Brazil, Colombia etc). In Colombia, it is found very easily and in Florida (USA) it was introduced about 30 year ago and now it seems it is everywhere. I have found it in my backyard a few times.
From John Wightman:
Ernst and I (and others) worked on Spodoptera lituraas a post rainy season peanut pest in South India. It did its best to decimate this crop over a 230 x 50 km tract aided by the farmers who applied about 12 insecticide applications over a 120 day growing period. Once we had persuaded lead farmers not to spray, to attract birds their field with perches and to add a little diversity (sunflowers) the problem was as good as over – thanks to the sterling work of NGO friends aided and abetted by Peter Kenmore’s rice IPM program that ran in parallel – not to mention the millions of ladybirds that came to help by eating the Spodopteraeggs and small larvae.
From Graham Walker:
We have studied the non-target impacts (on various natural enemies) of different ‘selective’ insecticides for control of caterpillar pests over the years (direct application onto insects, and the non-target impact of insecticide residues on leaves). I would recommend Bt spot-spraying for small caterpillars, but when the caterpillars get large we know that Bt sprays are not very effective (the large caterpillars do not ingest enough residue to kill them). So, for large caterpillars I would recommend applying one of the diamide insecticides, cyantraniliprole or chlorantraniliprole. They are registered under various trade names around the world and we have found them to be less harmful to various predators and parasitic hymenoptera than other mode of action (MoA) insecticides, apart from Bt.
Another comment from Henry Murillo: I just would like to add that I have seen the Bt aizawai strain working better on Spodoptera. I am not sure if it was the strain you have been testing. Growers can also try baits. A mix of Bt or compatible insecticide with rice hulls, straw or bran plus molasses. It can be added to the whorls when Spodoptera is hiding/feeding inside. It is very attractive to them.
And Graham Walker replied: Yes, I believe baits added to the whorls are a good idea. In Vietnam, they drop in a few granules of a fipronil bait for control of S. litura. However, best to control the egg-masses and small masses of caterpillars before they become large caterpillars. We recommend a twice-weekly ‘scout and squash’ strategy.
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