Following on from the recent interest in the aphid mummy found on the nursery, here is some more information about predatory bugs and how they can be used in the nursery or a garden setting.
Biological controls such as parasitic wasps and nematodes are used by nurseries to control insect pests such as aphids and spider mites. In the garden, these beneficial bugs are less under our control, but that does not mean they are not effective. On the nursery, these predators are used in controlled areas such as in the glasshouse where the atmosphere can be controlled and all exits sealed. In these conditions, nematodes can be used to control sciarid flies, thrips and vine weevils. These microscopic worm-like creatures are supplied in a gel-like carrier and then applied to the crop in water as a drench. The nematode then seeks out a host, enters the body and releases a bacterium, which will kill the pest. Parasitic wasps can be released into a controlled environment. They are applied to the crop as aphid mummies. The adult wasp, when it emerges, looks for an aphid to lay their eggs into and repeats the process. Different species of wasps attack different aphids, so correct identification is important.
We all do our best to attract pollinator insects into our gardens by providing insect hotels and planting areas that suit how they feed; unfortunately, this also attracts the bugs we don’t want to see, such as aphids and midges. So, before you reach for the chemicals, think about your first line of defence being the beneficial bugs found naturally in your garden. Don’t underestimate a Ladybird; think of these as the bouncers to your flowerbeds. They are voracious beetles that can eat 5000 aphids in a lifetime. This is due to the larvae and the adult being predators, which will also munch their way through midge larvae and small caterpillars.
Other beneficial bugs that you will come across are lacewing, the larvae, and the adults will predate on aphids. They will even go to great lengths to camouflage themselves with the carcass of dead aphids so they can sneak closer to their prey without being detected. Hoverflies, as well as being good pollinators they will predate on aphids and small prey. Another bug which will be familiar to those who work in gardens are the Flower bug (also known as the Pirate bug due to its markings) because as well as all the good work they do in the garden to feed off aphids, caterpillars and midge larvae, they do bite us too.
This use of beneficial bugs as a line of attack against pests is a good way to reduce our reliance on chemical controls. It encourages the food chain to develop in the garden as the beneficial bugs will themselves become lunch for birds and small mammals. It is also a less discriminatory method of dealing with insect pests than just blanket spraying the whole crop or garden with chemicals.
Posted 26th Jan 11:16am
