Pheromones are a special kind of perfume. The most well known are those produced by female moths to attract males.
Pheromones can work well as control agents against small moths where mated females don’t fly too far.
They are useless as control agents for large moths like Heliothis and armyworms that fly hundreds of kilometres in a night and mate outside any area treated with a pheromone disruption agent.
Commercialisation (Continued from last issue)
Attractive perfumes are not much use to farmers until they are turned into products that are effective, practical and easy to use.
Two small Australian companies developed commercial formulations of these perfumes for control of Heliothis on cotton.
They were liquids consisting of perfume mixes combined with sugar and various inert ingredients—essentially sprayable baits. The formulations did not contain insecticides—a small quantity of registered insecticide was added by the farmer prior to use.
For the product I developed, a strip was applied along the crop rows as a ‘water pistol squirt’ at 50 to 100 metre intervals over the crop at the rate of 0.5 to 1.0 litres per hundred metres of row (diluted 1:1 with water, this amounted to 2 litres per hectare). It could be applied from a simple ground rig or from the air, making it fast, cheap and easy to apply.
In vegetables, the liquid formulation could be applied around perimeters of fields, on headlands and on strategically placed trap rows of crops like forage sorghum within large area crops.
Does it work?
The short answer is yes.
After application, moths can be seen flying across the top of the crop from a large distance away. When they arrive, they feed enthusiastically on the bait.
We found that we could kill large numbers of moths and about half of these were young females before they had laid eggs.
The populations of adult moths crashed to almost zero in one or two nights, followed by the newly laid eggs on the crop.
The insecticide usage was reduced by 99% compared with that required for a cover spray.
Providing a fast knockdown insecticide is used, dead moths are readily visible in the treated rows and the next two or three on each side.
Needless to say, a sprayable bait targeting adult moths coming into the crop needs to be applied at the beginning of flights or regularly at lower rates as a preventive measure.
Baits for adults are not useful when the crop is already loaded with eggs and larvae.
Non target insects (cont next issue)
See this article in Tree Fruit Feb 2019
