Optimisation and validation of a floor trap for the detection of insect pests in empty stores, in bagged stacks and on flat surfaces in the cereal and food trades

Abstract

The aim of the research reported here was to develop and assess a trap to monitor the principal crawling beetle pests of stored products in empty premises, in bagged stacks and on flat surfaces in grain stores and flour mills in the UK.

The study started by testing different monitoring devices in laboratory arenas. In these tests, a CSL prototype trap derived from the CSL pitfall cone trap was compared with the Igrox Insect Monitoring Peanut-free Bait Bag, the Storgard® Flit-Trak M2 trap and the newly introduced Pantry PatrolT trap. The beetles tested were six species chosen either because of their important pest status or because they might be difficult to trap. The Pantry Patrol trap gave surprisingly poor results and was therefore not considered further. The CSL prototype trap containing a carob lure was as good as, or better than, the Flit-Trak M2 trap containing both food oil and pheromone lures in catching Oryzaephilus mercator, Typhaea stercorea, Tribolium confusum and Cryptolestes ferrugineus. The CSL prototype trap containing a carob lure and the Flit-Trak food oil was as good as the Flit-Trak M2 trap in catching the other two species tested, Sitophilus granarius and Rhyzopertha dominica.

Comparisons were then made between traps in a grain store, in a flour mill and in some laboratory rooms. These tests demonstrated that the CSL prototype trap containing the carob lure and the Flit-Trak food oil was capable of catching the following additional insects: Oryzaephilus surinamensis, Tribolium castaneum, Lasioderma serricorne and psocids. They suggest that this trap was at least as good as the Flit-Trak M2 trap. The CSL prototype trap has the significant advantage over the Bait Bag that it does not contain food which might, if neglected, act as a source of sustenance for pests and therefore possible re-infestation. Of the traps tested, the CSL prototype trap is the only one which is sturdy, reusable, easy to assemble and leaves the catch easy to identify. For these practical reasons, combined with its proven effectiveness in trapping the above important species, the CSL prototype trap containing a carob lure and the Flit-Trak food oil lure was considered to be the most effective trap.

The CSL prototype trap can, in its present form, contribute usefully to integrated pest management programs by allowing users to get early warning of infestations and demonstrate the effectiveness of the appropriate avoiding action. It is proposed that future work should include simplification of the lure. Then companies to manufacture and market the trap should be identified and an information leaflet written to describe the trap and include guidelines for its use.

SUMMARY

To maintain the quality of post-harvest cereals it is essential to detect pest infestations as early as possible. Early detection would permit control strategies to be devised which reduce the use of persistent contact insecticides and consequently reduce the risk of contamination of food and the environment. The ability to detect insect infestations in empty stores after cleaning would also give an indication of the effectiveness of the cleaning process at removing residual populations of stored commodity insect pests, or indeed whether a residual pesticide treatment is even necessary.

The ideal monitoring trap for use in structures would be inexpensive, re-usable, sturdy, easy to use, and be free from oil and food baits which are potential stored commodity contaminants. Currently, commercially available floor traps do not fulfil these requirements. The bait in 'bait bags' (Pinniger and Wildey, 1979) is not completely contained, it may also be a refuge for feeding and breeding pests, and the pests themselves are not contained. The Storgard® Flit-Trak M2 (Fisher et al., 1993; US Patent 5,090,153) contains oil which could contaminate stored commodity or constitute a slip-hazard if it is spilled. The Trappit® Tribolium Trap, Agrisense® Insect Monitoring Trap and Russell Environmental Products SafestoreT Trap are not re-usable. Insects tend to gather under rather than in these types of traps and, when they do enter the traps, they are difficult to identify.

A prototype trap with a flat base has been developed at CSL which is cost-effective, re-usable, sturdy, easy to use and which allows easy identification of insects because it does not rely on oil or sticky surfaces to trap them. The CSL prototype trap was based on technology developed in the design and production of the Pitfall Cone (PC) trap. The PC trap was developed with the help of HGCA funding (Pinniger et al., 1990) to meet the need for improved insect monitoring in stored commodities (Anon., 1995; Cogan et. al., 1990). It has been shown to be at least as effective as other trap designs but with the advantage of cheapness and the ability to trap insects both on and below the surface of stored commodities (Cogan and Wakefield, 1994).

The aim of the work reported here was to develop and assess a trap which would:

detect and monitor the principal crawling beetle pests of stored products in empty premises, bagged stacks and on flat surfaces in grain stores and flour mills in the UK,
do so with an effectiveness which is at least as good as existing traps
meet all the criteria for ease of use and low cost
allow users to get early warning of infestations and take appropriate avoiding action.
The research started with tests in laboratory arenas of different monitoring devices to trap the following six beetle species: Tribolium confusum, Sitophilus granarius, Oryzaephilus mercator, Cryptolestes ferrugineus, Rhyzopertha dominica and Typhaea stercorea. The monitoring devices compared were the Igrox Insect Monitoring Peanut-free Bait Bag, the Pantry PatrolT trap, the Storgard® Flit-Trak M2 trap, and the CSL prototype trap. All these were tested with the attractant lures with which they are normally supplied. The most promising traps were then compared in two week preliminary trials in three types of premises: a grain store, a flour mill and some laboratory rooms.

The results of the laboratory comparisons of the traps showed that the CSL prototype trap with the carob lure alone was significantly better than the Pantry Patrol trap in catching all of the species tested other than S. granarius. These disappointing results for the Pantry Patrol trap were surprising given its introduction being so recent, and in consequence its use was not considered further.

The CSL prototype trap with carob lure alone was significantly better than the Flit-Trak M2 trap in detecting O. mercator and T. stercorea and it was as good as the Flit-Trak M2 trap in detecting T. confusum and C. ferrugineus. The catch of S. granarius in the CSL prototype trap was as good as in the Flit-Trak M2 trap when the former contained a mixture of the carob lure and the food oil from the Flit-Trak M2 trap. Similarly, the catch of R. dominica in the CSL prototype trap was as good with the mixture of carob and Flit-Trak food oil as it was when using the Dominicalure pheromone for this species. The fact that the CSL prototype trap with the combined carob and Flit-Trak lures was as good as the Flit-Trak M2 trap itself for both S. granarius and R. dominica suggests that it is the trap of choice.

The results of the premises trial in the grain store showed that the CSL prototype trap was at least as good as the Flit-Trak M2 trap and the Bait Bag in pinpointing infestations of O. surinamensis and S. granarius (from the number of positive traps) although the Bait Bag seemed rather better at pinpointing psocids. In terms of numbers of insects caught, the CSL prototype trap was as good as the Flit-Trak M2 trap but not as good as the Bait Bag for catching O. surinamensis. With S. granarius, the CSL prototype trap was as good as both the Flit-Trak M2 trap and the Bait Bag, although in all cases the numbers of insects were very small.

In the flour mill, the CSL prototype trap was better than the Flit-Trak M2 trap in terms of species and numbers caught and positive traps. The Flit-Trak M2 trap detected only T. castaneum whereas the CSL prototype trap detected T. castaneum, S. granarius and O. surinamensis.

In the laboratory rooms, the CSL prototype trap detected L. serricorne, O. surinamensis and psocids. L. serricorne and O. surinamensis were each detected in one room by the CSL prototype trap but not by the Bait Bag.

For use in flour mills, the CSL prototype trap has the further significant advantage that it does not depend on a sticky surface: sticky traps are currently used in flour mills but are often rendered ineffective by the dusty conditions. This conclusion is further supported by the practical reason that of all those tested, the CSL prototype trap is the only one which is sturdy, reusable, easy to assemble and leaves the catch easy to identify.

It is proposed that future work should include simplification of the lure to aid quality control. Then it would be necessary to identify companies to manufacture and market the trap. An information leaflet describing the trap should be written. This would include guidelines for its use.