Using wet traps to attract truffle beetle
Truffle beetle (Thalycrodes mixta, Family Nitidulidae), is still a concern in one WA truffle orchard. As part of the aim to protect truffles from the beetle, we are studying the seasonality of the beetle. An important aspect of this is continuing to fine-tune monitoring techniques. Previously we were using pitfall traps and flight intercept traps and this spring we are assessing wet traps as well.
Wet traps use the same equipment as the pitfall traps that we have described in previous newsletters, the difference being a solid base container is used and 100mL of a 50:50 beer: molasses mix plus one teaspoon of yeast is added. These molasses-yeast traps are used by beetle specialists to capture nitidulid beetles in a variety of environments, and are particularly effective for that family alone (thus excluding the bycatch common in pitfall-based survey methods).
We have installed wet traps in four orchards this spring to compare against standard pitfall traps baited with truffle. Monitoring took place over spring and early summer, the period of peak beetle activity last year. We found truffle beetle only in one orchard this spring/summer, which had confirmed truffle beetles in the 2016 and 2017 seasons. The wet traps are performing well. Beetles were found in wet traps nine weeks earlier than in the dry traps and so far over 98% of truffle beetles collected this spring and summer have been from wet traps.
Trials in Spain looked at using pitfall traps for mass trapping as a control method for the European truffle beetle, Leiodes cinnamomea. Preliminary results found that in orchard sectors with mass trapping there was less damage and less severe damage to the truffles. They recommended installing traps at a density of 30/ha. It is not known if a similar mass trapping control system would work for the Australian truffle beetle. Although, it is good to know that the beer, molasses, yeast combination is more attractive to the beetles. This is encouraging for both improved monitoring and potentially as a means of management by reducing beetle numbers.