Location: Temperate Tree Fruit and Vegetable Research
Project Number: 2092-22430-003-065-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2024
End Date: Sep 29, 2027
Objective:
Objective 1: Determine click beetle seasonal phenology of major pest species across Washington state.
Objective 2: Assess the efficacy of currently registered and experimental insecticides on click beetles.
Approach:
Objective 1: Trapping will target regions that grow potatoes and other affected crops and will occur for two years during the growing seasons. At each trapping site we will place several pitfall traps that will be baited with pheromones of several species. Traps will be monitored biweekly during growing seasons, and lures will be refreshed monthly. Captured beetles will be counted and identified using taxonomic keys or by using molecular analyses.
The development of phenology models will begin following species identification from first year trapping surveys. Beetle capture data will be separated by species, and relative abundance of each will be plotted to degree-days. Daily maximum and minimum temperatures will be collected from nearest AgWeather station or temperature monitoring devices. Various degree day calculation methods will be tested, and horizontal and vertical threshold cut-offs will tested on increments until an optimal fit is determined for each species. At the end of the third sample year, the 50% percent of beetle abundance data will be used to parameterize the model and the remaining 50% will be used for validation.
Objective 2: We will examine repellents and selective insecticides. For both experiments, live beetles will be collected using two general methods: light traps such; and from within a plot or the surrounding vegetable either by hand or using a reverse leaf blower.
Repellent Choice Test. These experiments will be established in an enclosed screen house. Wheat grass will be planted into planting trays and organized in a randomized complete block design. In spring, wheat trays will be sprayed with kaolin, mineral oil, or left untreated as a check (10 trays per treatment). At least 200 beetles will be released into the center of the screen house following sprays. Beetles will be counted in wheat tray treatments every 24 hours for two weeks. As click beetle individuals will be removed as they are found to prevent double counting and for identification to species. Wheat tray will be kept alive in the screenhouse until autumn, at which point they will be sampled for wireworm larvae.
Selective insecticide assays. Greenhouse bioassays will be used to test selective insecticides against click beetles. Insecticides tested will include two diamides, an insect growth regulator, two organic materials, and a pyrethroid, against an untreated check. Bioassay arenas will be established using plastic cups, planted with wheat. Collected beetles will be randomly assigned to groups of 10 to be released into each container. Immediately after beetles are introduced into containers, the assigned treatment material will be sprayed over beetles and wheat using an atomizer, then arenas will be covered with a mesh lid. Spraying beetles and plant material will best mimic a field exposure. Arenas will remain in a screen house to utilize natural environmental conditions of ventilation, temperature, and light. Mortality will be checked every 48 hours for two weeks. For both experimental assays, differences between treatments and untreated checks will be assessed using paired contrast statements.
