“The more clearly we can focus our attention on the wonders and realities of the universe about us, the less taste we shall have for destruction.”

Rachel Carson 1954

Conception, realization and experimentation of an auto-dissemination trap to control insect pest in perennial crops (Ordonez & Goedert, 2003-pending patent)

Bio-control of Coleopters with micro-organisms is difficult as few biological compounds are really able to totally substitute chemical pesticides available at present on the market.
Entomopathogenic fungi such as the green muscardine, Metarhizium anisopliae (Metschnikov), Sorokin and the white muscardine, Beauveria spp., have been studied as bio-control agents against the larvae and adults of Coleopters (Kempkes et al, 2004). Nevertheless, the problems involved with pathogenic disease dissemination in the larvae habitat have made their use arduous.

Experiments consisting in releasing the adults of Coleopters which transport pathogenic fungus were carried out at the end of the seventies (Zelazny et al, 1978). In the nineties, traps to disseminate entomo-pathogenic fungi against cabbage insect pests showed the effectiveness of this method (Pell et al, 1993). Insect pathologists now know that it is possible to propagate a disease by using infected individuals which can disseminate fungi as well as bacteria (Payne J., 1991), thus controlling the level of a certain insect’s population. For instance, Klein et al (1999) developed an auto dissemination trap to contaminate Japanese beetles (Popillia japonica Newman) with green muscardine (Metarhizium anisopliae (Metschnikov), Sorokin).

Larvae of the pest insects (Coleopters) can be unreachable with the usual treatments; therefore the auto-dissemination of entomopathogenic fungi techniques can be efficient.

Image

J.C. Gregoire from ULB, Belgium has invented a bottle-trap system for monitoring bark beetle forest pests (1999). Based on his trap system, we have designed and realized an auto-dissemination trap (prototype conceived and developed by Ordonez and Goedert, 2003).

Image

Description of our auto-dissemination trap:

To Gregoire’s trap system we have coupled an inoculation chamber. The composition of the trap is as follows:

1. A plastic funnel by which the insects penetrate into the trap. To the funnel we hang a sexual pheromone which attracts the insects.

2. A body with a plastic cylindrical tube is horizontally fixed. At the extremity of the tube, a pane lets the light pass through so that the insects attracted by the sexual pheromone (and eventually captured) will move towards an inoculation chamber fixed in the middle of the tube. The other extremity of the pipe is closed by a grid in which an alcohol scent is passed.

3. A bottle containing alcohol is fastened to the body of the trap. This feature is also a lure to attract the insects.

4. The inoculation chamber is a cylinder of 3 cm in height and diameter fixed on the body of the trap. The inoculation chamber is loaded with an entomo-pathogenic fungus powder formulation (60% of an active ingredient), plus an additive (30%) that helps to homogenize the active ingredient powder and a desiccant (10%).

For our first bio-essays we have placed in-between the inoculation chamber and the glazed end a bottle with holes which is used to collect some of the captured insects.
The principle of operation of our auto-dissemination trap is simple:

Insects are fattaly drawn initially by the odour emitted by the synthetic pheromone (distance pheromone) placed on the funnel and then by the alcohol vapours which act as attracters or alike resting pheromone (as it recalls to insects the terpens compounds secreted by decaying trees). Insects fatally drawn yet fall on a grid fixed onto the tube. The other role of the grid is to allow the rain water that is collected by the funnel to run-off.

Once the insects are caught into the trap body they will search for the light coming from the other end of the tube. In its walking progression, they will mandatorily pass by the inoculation chamber and the only possibility they will have is to fall into the bottle with the holes.

In 2004 we captured Coleopters in a conifers forest. When the insects were brought to the laboratory conditions, we observed the presence of the pathogenic fungus – kind of confirmation of Koch postulates –.

With this prototype trap we are searching to prove that dissemination is an efficient system to reach Coleopters larvae, particularly in the conifers plantation. Tests on perennial crops were carried out.