Simulation-based evaluation of two insect trapping grids for delimitation surveys

Area of Science:

• Entomology
• Pest Management
• Ecological Modeling

Background:

• Delimitation trapping surveys using square grids are standard for exotic insects in the USA but lack rigorous evaluation.
• Existing grid designs have not been scientifically assessed for optimal effectiveness and cost-efficiency.

Purpose of the Study:

• To investigate the effectiveness of current delimitation trapping grid designs for Acrolepiopsis assectella (leek moth) and Ceratitis capitata (Mediterranean fruit fly, Medfly).
• To develop improved, more cost-effective grid designs using simulation methods.

Main Methods:

• Simulations were used to evaluate two representative square grid designs (8-km for leek moth, 14.5-km for Medfly).
• Performance was measured by the mean probability of pest capture (p(capture)).
• Grid compositions and design factors were analyzed to propose optimized circular grids.

Main Results:

• Standard grids showed high p(capture) (0.86 for leek moth, 0.71 for Medfly), but egress testing indicated they were oversized.
• Improved circular grids significantly reduced costs: 80% for leek moth (177 traps, 4.8-km diameter, p(capture)=0.73) and 86% for Medfly (232 traps, 4.8-km diameter, p(capture)=0.66).
• Core area captures contributed substantially to the overall detection probability in standard designs.

Conclusions:

• Simulation modeling is a valuable tool for optimizing pest trapping survey designs.
• Optimized trapping grids can maintain high pest detection probabilities while drastically reducing costs.
• Current standard trapping grids for exotic insects in the USA are likely inefficient and oversized.