Sustainable Management of Spotted Lanternfly by Native and Naturalized Predators

View the project report

Commodities

• Fruits: grapes

Practices

• Pest Management: biological control

Spotted lanternfly (Lycorma delicatula, SLF) is an invasive sap-feeding insect that poses a serious threat to several agricultural and ornamental industries, especially grapes, fruit and walnut trees, and hops. The invaded range that started in one county in PA in 2014 has expanded to 11 states in the Northeast, Midwest and Mid-Atlantic regions. To prevent losses from this pest, it is necessary to find control methods that are sustainable and cost effective, for which biocontrol shows great promise. A potential source of biocontrol agents that has yet to be explored are predatory insects that are endemic to the U.S. For this project, I will identify the most effective predators of different SLF life stages through field surveys and further assess predation efficiency of commercially available or easily collected predators (e.g., convergent ladybugs, harlequin ladybugs, green lacewings, brown lacewings, wheel bugs, and spined soldier bugs). I will also determine functional response relationships between these predators and increasing SLF density to determine the most effective predators. A functional response is when the rate of predation increases with increasing prey density. My findings will be shared through direct interactions with stakeholders by our PSU Extension collaborator and PSU Extension Educators, posts on the Penn State Extension webpages (https://extension.psu.edu/spotted-lanternfly; https://extension.psu.edu/spotted-lanternfly), Penn State News, social media, and presentations I will give at grower meetings (e.g., PA Wine Marketing and Research Board, Ag Progress Days, and the PA Farm Show). I also expect to publish at least one peer-reviewed paper from this project.

1. Survey for insect predators that are consuming different SLF life stages in the field.

Justification: While we have a great deal of data on predators of adult SLF from a citizen science project, we did not receive many reports of predators of earlier life stages, including eggs and nymphs, likely due to their inconspicuous nature. Identifying wild predators that feed on different life stages will indicate which species to encourage through conservation biocontrol or release for augmentation biocontrol.

2. Identify which insect predators have the highest rate of SLF consumption by life stage over time.

Justification: By identifying which insect predators already present in the introduced range have the highest rate of SLF consumption, I will collect information that is useful for the development of a biocontrol program for the sustainable management of SLF. Predators that feed at higher rates than others will have the most promise and should be the foci for future work. I will test species that are commercially available or can easily be collected and reared for use in augmentation or supported through conservation biocontrol. For this project, I will test convergent ladybugs (Hippodamia convergens), harlequin ladybugs (Harmonia axyridis), brown lacewings (Micromus variegatus), and green lacewings (Chrysoperla rufilabris) to determine if they will feed on SLF eggs and early instar nymphs (1^sts and 2^nds) since they are generalist predators that feed on insect eggs and small soft-bodied insects. We will also test wheel bugs (Arilus cristatus) and spined soldier bugs (Podisus maculiventris) against the nymphs and adults since these predators feed on larger mobile insects. Wheel bugs are not commercially available but frequently attack SLF in the field (Johnson pers. obs). We have also observed wheel bug egg masses laid next to SLF egg masses and received reports of nymphal wheel bugs feeding on SLF nymphs and adults.

3. Determine which predators display a functional response to SLF density.

Justification: The most effective biocontrol agents typically show a functional response to their prey, increasing their consumption rate as prey density increases (Jeschke et al., 2004). Determining which of the predators tested in Objective 2 show a functional response to SLF is useful for the selection of the most effective biocontrol agents for further evaluation. This information will also guide initial predator to prey ratios to test for efficacy in a crop setting for control of SLF (such as in an orchard or vineyard).