We’re bugging out!

  • What are ‘good bugs’?

  • What is Integrated Pest Management?

  • What is the APPF’s approach to a harmonious plant growth environment?

Science fiction couldn’t write it better… ‘A wasp homes in on its prey, detecting the distress signals of an infested plant and the honeydew secretions of hungry aphids. It locates and injects a living aphid with an egg, which in time, hatches inside the aphid and consumes it from the inside. Two weeks later an adult wasp will burst out from the mummified shell of the now dead aphid…’

Sounds awful right? But this is nature, integrated pest management and agroecology at work. And if you have a crop to protect, it’s exciting!

Most are insects are beneficial. In natural ecosystems, pest species are kept under control by climatic conditions, food availability and natural enemies. In a production environment, natural enemies, known as beneficials, are organisms that feed on or otherwise kill the target pest. They may be predatory insects or parasitoids, fungi, bacteria, viruses or insect feeding birds.

Predators:

  • are organisms that feed directly on their prey, eating a wide range of pests such as mites, aphids and other insects that are mostly slower moving or at vulnerable growth stages, such as eggs and pupa
  • includes both insects such as lacewings, ladybird beetles, predatory shield bugs, pirate bugs, and hoverflies, as well as spiders and predatory mites (arthropods)
  • are known to attack insects such as aphids, thrips, moth eggs, and small, medium and large caterpillars
  • will supplement their diet with nectar, pollen and fungi as adults
  • are easily killed by broad-spectrum insecticides and some narrow-spectrum insecticides
  • may be reared commercially

Parasitoids:

  • use pest insects as hosts
  • are generally tiny wasps but may also be parasitic flies
  • lay their eggs within or on the host pest at a critical life stage, completing their entire development with that host by consuming it
  • are recognised as important pest management tools
  • need to supplement their diet with nectar as adults, so some flowering weeds may be important for their continued presence
  • are easily killed by broad-spectrum insecticides and some narrow-spectrum insecticides
  • can be reared commercially
  • are monitored by collecting and rearing the relevant pest stages to see whether parasitoids emerge

Why is the APPF ‘bugging out’?

Every day we watch closely over the environments of the plants in our care, monitoring heat, light, water, soil and so on. But it is a well-known fact, no matter how well managed your growth environment is, bugs have a way of finding their way in. These troublesome types may include Western Flower thrips (Frankliniella ocidentalis), various aphids, two-spotted mites (Tetranychus urticae) and greenhouse whiteflies (Trialeurodes vaporariorum) to name a few.

Around the world, growers, farmers, researchers and horticulturalists have used chemical spraying to manage these pests, however, many pests are now showing clear signs of acquired resistance to chemical controls. Use of stronger chemicals such as organophosphates usually only deliver a temporary drop in numbers and increase exposure risks to the operator, staff and researchers who may later handle the plants.

With a clear view to ensuring the safety of our plants, our staff, our users and our environment, our horticulture team investigated the Integrated Pest Management (IPM) principles being embraced by the commercial horticulture industry across protected and field crops. By using IPM, also known as Integrated Crop Protection (ICP), the growers are able to achieve better value out of fewer insecticides while improving the control of pests.

What is Integrated Pest Management (IPM)?

IPM has three elements: prevention, monitoring and intervention. It requires the careful consideration of all available pest control techniques and subsequent integration of appropriate measures that discourage the development of pest populations, keeping pesticides and other interventions to levels that are economically justified and reduce or minimise risks to human health and the environment. IPM emphasises the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms. (Food and Agriculture Organisation of the United Nations, 2012).

So, what is the APPF doing for IPM?

The APPF Adelaide node now runs a regular fortnightly program, releasing predatory mites and insects into the greenhouses.

“We rotate a variety of predators that prey on all lifecycle stages, from larvae through to adult pests. The use of pesticides in this regime is, of course, counterproductive, as there is often a 3-8 week period where residues will kill the beneficial predators. When introducing an IPM plan make sure you learn what the different life-cycle stages look like for both beneficial insects and pests – you don’t want to accidentally wage war on the ‘good guys’,” explained Robin Hosking, Manager, Horticulture.

“As an example of the effectiveness of our IPM, we have greenhouse rooms that have not been sprayed for 3 months and the pests are well controlled. Previously I had been spraying these rooms as often as weekly to fortnightly.”

IPM Technologies provided IPM training to the APPF.

The APPF sources its good bugs from Bugs for Bugs and Biological Services.

 

LEARN MORE

Watch:

Pests, good bugs and where to find them:

More information on biological control/IPM:

A LITTLE MORE ABOUT Aphidius colemani

Aphidius colemani are parasitic wasps about 2-3mm long and black with brown legs. They look very similar to a small black ant with wings, but the antennae are long and slender. The wasp deposits an egg into the aphid in a matter of seconds. The aphid continues to move and feed for 3 days after the egg has been deposited. When the egg hatches, the Aphidius larva begins feeding on the aphid, eventually killing it. The parasitoid develops within the aphid body which at this stage is called a “mummy”. The mummy looks like an over inflated bronze aphid. The Aphidius chews a hole through the back of the mummy and emerges as an adult wasp ready to deposit eggs in live aphids. Complete development time is temperature dependent, but is about 12 days at 25°C. This is longer than the development time of aphids, but each Aphidius female can parasitise over 300 aphids in her lifetime which can last 2-3 weeks when food and water are available. Where wasps are present surviving aphids react by emitting an “alarm” pheromone which causes the colony to flee, often falling to the ground where they die. Appropriate for garden and greenhouse use, Adphidius can be used both as a preventive measure and to combat infestations. Proof they’re at work can be found by searching for the brown, mummified shells left of dead aphids.

2018-04-19T16:47:57+00:00