Hot house pest problem arrives with rain
A VERITABLE plague of silverleaf whitefly has taken coastal hot house farmers by surprise, and left others relishing the fact that they adopted integrated pest management as part of their hydroponic crop profile.
However, even the greatest population of predatory wasp or mite has trouble keeping an appetite for this many tiny bugs.
The blame lies with the current weather conditions and with the acres of soybean growing in abundance throughout the district.
It seems a bit of rain after such a long period of dry has created a breeding frenzy and hothouse growers close to a source have been caught in a challenging situation.
Graham Grant, of Wardell Hydroponic Lettuce, is a firm believer in integrated pest management, using predatory insects to keep control of problem critters, like whitefly.
In normal times the predators keep on top of the prey, provided green trimmings are disposed of properly and housekeeping is looked after. Standing water, for instance, creates an excellent breeding ground.
But when bug populations start to increase, the vigilant grower starts to spray - at first with "soft" chemicals, and when the problem bugs start to explode with "hot" chemicals that also kill the predatory protectors.
"Integrated pest management, using predatory bugs likes wasps, is just one tool in the box," Graham said.
"It is an involved subject, a whole philosophy in which we have to monitor and understand the lifecycle of insects.
"For instance, some predatory bugs attack fully-grown pests while others target juveniles."
In Graham's case he has been able to create a semi-barrier around his greenhouse by spraying soybean growing on his property. Green waste is now dumped in a spot seeded with predatory bugs.
Did you know?
As a normal course of action, sticky cards are placed around the farm to monitor bug populations.
Predators include wasps, mites and lady beetles.
Certain bacteria keep problem bugs at bay by attacking them from their insides.
Bugs quickly develop resistance to a particular insecticide, requiring a constant change of tactics in the war against them.