The Problem Studied

The rapid development of resistance by flies to insecticides, even those with novel modes of action, has led to an imminent collapse in poultry producers' ability to control them, according to Christopher J. Geden from the USDA in Gainesville, Florida.

New fly control tools are needed, and they must be environmentally safe as well as effective and economical.

The insect growth regulator, pyriproxyfen (PPF), is a synthetic analogue of an insect hormone that can be used to block fly larvae from reaching adulthood in a manner similar to Larvadex.

Direct treatment of manure is problematic because treated areas rapidly get covered over with fresh droppings.

A recent discovery in the area of mosquito control has shown an exciting new way of delivering PPF to target larvae. In this method, called autodissemination, egg-bearing females are lured into a station where they acquire a payload of PPF that they then transport and deliver to egg-laying sites.

The goal of this project, sponsored by the US Poultry & Egg Association, was to develop technology for autodissemination stations that lure flies in, treat them and release them to deliver PPF to hot-spots where larval breeding occurs.

Objectives

Dr Geden's study had three main objectives:

1. Determine the efficacy of different dust formulations of pyriproxyfen against the house fly (What kind of dust works best?)
2. Determine the amount of pyriproxyfen that the flies can transport (How big a payload can the fly carry and how potent should that payload be?)
3. Test of concept in large outdoor field cages.

Results

Three dust formulations were made by combining liquid concentrates of existing commercial products (Knack, Sumilarv, Nyguard) with diatomaceous earth and allowing them to dry. The three dusts, which had a maximum potency of five per cent PPF, were equally effective for fly control; LC50's ranged from 8 to 24ppm.

Autodissemination tests in small cages revealed that dusts with more than five per cent PPF were needed to provide adequate fly control because of the limited payload that flies can carry on their tarsi (feet). New formulations were made using technical PPF and different carriers and sticking agents. All six of these new formulations, with potencies of 22 to 80 per cent PPF, gave more than 93 per cent fly control. Treated flies retained the PPF payload for at least six hours after acquiring it.

Candidate autodissemination stations baited with molasses and Farnam fly attractant gave 86 to 92 per cent fly control in large outdoor field cages.

Impact

Dr Geden concluded from his results that the concept of using flies as autodissemination vehicles for pyriproxyfen is feasible.

The attractant station that was developed is composed of off-the-shelf components that are readily available to producers.

Further development/implementation of the technology will depend on field tests and commercial availability of a dust formulation of sufficient potency.

Pyriproxyfen has excellent potential for fly control, especially in applications for which Larvadex has historically been used by the industry.

November 2013