Broad spectrum insecticide spraying for the major insect pests during the growing or "spraying season" unfortunately decimates the natural enemies of these pests and also those of “secondary pests” like thrips, mites, felted coccid and scale. And extending the spraying season as has happened in recent years for many growers further makes it increasingly difficult for natural enemies to re establish themselves and to make a useful contribution.
Recent research and observations by crop consultants has indicated that good inter-row growth and plant variety increases non-economic insect populations and subsequently the numbers of beneficial insects in the orchard.
This helps make the orchard more resitant to pests - especially, we think lace bug - and provides a buffer in the system giving more time to make spray decisions and, in some instances, these natural enemies are able to keep pest populations in check on their own.
Good inter row growth during the growing season also provides a refuge for natual enemies so that their recovery is quicker after spraying.
Lacewing larvae are important predators in this mix and get knocked around during the “spraying season”. Further, close mowing during harvest period places a restriction in the re-establishment of non-economic and predatory insects in the inter-row.
By releasing lacewings we aim to re-establish and boost the orchard population. If we wait for local populations to build, this may or may not happen.
Adult lacewings in macadamias
Lacewing adults feed on nectar, pollen and insect honey dews and lay their eggs in the canopy nearby as well as in the inter-row. Out of season macadamia flower is the means by which lace bug moves from season to season and is a likely site for lacewing egg laying.
So the release strategy is to boost lacewing populations through autumn to keep lace bug and other pest numbers down and result in a slower build up of these pests in spring, providing more time for nuts to set and so delay the demand to spray.
We think that releasing lacewing adults is more effective than releasing just eggs or larvae. Its hard to apply eggs and larvae into trees where we want them - near pest outbreaks - and where they can get a feed quickly. The adults will distribute their eggs high up into the trees and near sources of food for the hatching larvae.
In the wild, when lacewing adults emerge from their pupal case they disperse and seek a food source before laying eggs. In the laboratory, we can rear them through to adulthood and can ship them to growers when several days old.
They have been well fed and ready to lay eggs - there may be some lacewing eggs already laid in the container. Each adult female should lay over 200 eggs and live for a month or so. 100 females x 200+ eggs = 20,000+ eggs.
Laceing Info in PDF
Green lacewing larvae are voracious predators of many soft bodied insects including lace bug. Here with an aphid.
Green lacewing females lay their eggs on fine stalks and usually in groups.
Green lacewing adults are despatch in plastic containers with shredded paper and some honey for food..