Springtails feed on the germinating seeds of lettuce, causing severe stand losses in the northern Salinas Valley of California. Springtails are very tiny (2.5 mm long) and live in the soil, making them difficult to see. Researchers use the Berlese funnel method to sample soil. From a grower’s standpoint, the Berlese funnel method would not only be cumbersome and laborious, but also may not provide information quickly enough for making management decisions. There is no grower-friendly tool available to monitor springtails in commercial lettuce fields. As a result, growers apply pyrethroid and neonicotinoid insecticides to prevent damage.
Identifying an effective monitoring tool for springtails could be the first step toward developing a threshold for determining when to manage springtails. Potato slices are typically placed on the soil surface to attract another soil pest, garden symphylans. IPM Advisor Shimat Joseph examined the potential use of potato slices to see if they could also be used to capture springtails. Beet slices were tested because light colored springtails might be easier to see on them than on off-white potato slices and their high sugar levels might make them a more attractive bait.
Joseph compared the number of springtails found on potato and beet slices with springtails extracted from the soil using the Berlese funnel method. Results suggest that both potato and beet slices were attractive to springtails. Beet slices consistently captured greater numbers of springtails when compared to the numbers found on potato slices or in the soil. In addition, keeping beet slices out in the field for 5 days still captured springtails. Beet slices collected after 1 to 4 days captured a greater number than beet slices collected on day 5.
Growers and pest control advisers now have a tool to monitor lettuce fields for the presence of springtails. Joseph has since observed that many growers are using beets instead of potatoes to indicate whether springtails or symphylans are active before or at planting. Pest control advisers working in the affected fields are deploying these baits and it is an integral part of their decision making for managing springtails in lettuce. Rather than applying pesticides preventively, pesticide applications can be made based on whether springtails are in the field, reducing the amount of pesticide applied and saving the grower the application cost.
Joseph is working towards an IPM program for springtails by first developing a way to efficiently monitor for their presence. If numbers on beet slices can be correlated with lettuce damage, a threshold of when to make management decisions can be determined, ultimately protecting the lettuce industry, which was valued at $1.2 billion in Monterey County.
