Principle Investigator: Gadi V.P. Reddy

Project Personnel: Debra Miller, Kendall Franks and Govinda Shrestha

Western Triangle Ag Research Center,

Montana State University,

9546 Old Shelby Rd., P. O. Box 656,

Conrad, MT 59425

Aim of the Study

The aims of this study was to develop pheromone baited traps which will help in monitoring and mass trapping the pea leaf weevil population in the Golden Triangle areas of Montana.

 

Four images in a circle showing the life cycle of a pea leaf weevil.

Fig. Pea leaf weevil life cycle Materials Methods

 

Experiments were carried out at four locations: Conrad, Valier, Ledger and Chester in the Golden Triangle areas of Montana. Trap design were shown in figure-1. The rubber septa with pheromone lures were used. Traps without pheromone lures were used as controls. Tests were replicated three times at each site to yield 12 replications. Pheromone lures were loaded with 4- methyl-3, 5-heptanedione as described in Blight et al. (1984). These lures were obtained from Chem Tica Internacional S.A. (San José, Costa Rica).

 

Effect of trap design

In the first experiment, four different types of traps (pitfall, delta, ground and ramp traps) were placed at borders in the field. Overall, 96 traps were used (4 trap designs, each with and without lures × 3 replications × 4 sites). Each week, the trapped adult weevils were removed, counted and their numbers recorded. We interchanged trap positions weekly at each location to avoid positional effects on trap catch. The study was conducted from May-August 2016.

 

A bar graph showing the efficacy of each trap design.

Figure 2. Mean (±SE) number of pea leaf weevils caught by different trap designs

 

A double bar graph of the efficacy of pea leaf weevil traps.

Figure 3. Mean (±SE) number of pea leaf weevils caught in pitfall traps baited with different lures.

Results

Effect of trap design

Among the trap tested, pitfall traps caught higher number of weevils than other traps tested. This was followed by ramp, delta and ground traps.

Effect of lure type

The pitfall traps baited with pheromone impregnated rubber septa caught higher number of catches than the bubble septa and trap without pheromone septa.

Conclusions

The results indicated that the trap and lure type affect the response of pea leaf weevil to pheromone-baited traps. In particular, the pitfall traps with rubber septa lures gave the highest catches of pea leaf weevil. These results are useful and should be taken into consideration when monitoring and management strategies are developed.

Acknowledgements

This work was funded by the Montana Specialty Crop Block Grant Award#15SCBGPMT0005. Kendall stipend was funded by MAES summer Interns Program and WTARC Entomology/Insect Ecology at WTARC, Conrad.

References

Blight, M.M., J.A. Picket, M.C. Smith, and L.J. Wadhams. 1984. An aggregation pheromone of

Sitona leneatus, Naturwissenschaften 71: 480-481.