Biological Fly Control

Introduction

The control of flies in poultry farms is very difficult with the requirement to store dung and ongoing resistance to some of the knockdown products available. Increased washing of deep pit sheds to control salmonella in the environment has made manure management more difficult and wet manure is an ideal environment for flies to multiply.  Many farms have seen an increase in enteritis with loose droppings . This also leads to a higher moisture level in the manure and higher fly populations.

For many years the main method of control has been to kill the adult flies with the use of various chemicals and to apply a larvicidal product to the manure. This has been effective , but increased chemical resistance together with some evidence of resistance to the larvicidal products have led to large explosions in fly populations. At some times the pit is being treated 2-3 times per week. This is both expensive and time consuming.

There is some evidence that continual use  of knockdowns is  having an effect on bird health and production. Compliance with Health and Safety is also very important.

Biological control relies on various natural wasp parasites to build up in the house and predate upon the fly pupa. The adult female wasp lays an egg into the fly pupa which then develops into a wasp maggot and feeds upon the developing fly.  After about 2 - 3 weeks ( depending on temperature and other environmental factors ) the maggot develops into a wasp and emerges from the fly pupa case.

Two species of wasps are used in this system, Spalangia cameroni and Muscidifurax raptor. These are species found in Europe and have been identified by the Natural History Museum as such. In many houses there will be a natural population of either of these wasps, and the aim of biological control is to increase the predator population to control the higher levels of the fly .