PS 41-25 - Evaluating the impact of spotted lanternfly populations on non-target organisms in circle traps

Background/Question/Methods

Spotted lanternfly (Lycorma delicatula; SLF) first invaded southeastern Pennsylvania in 2014 and it has continued to spread throughout the northeastern United States. This larger planthopper can be seen in large aggregations at feeding sites, especially on tree-of-heaven (Ailanthus altissima). To minimize SLF impact, various trapping methods have been developed, including sticky and circle traps. There have been studies documenting the impact of sticky traps on non-target organisms, but none documenting circle trap impact. This study aims to address the following questions: 1) what non-target organisms are being caught in SLF circle traps on tree-of-heaven and 2) how do spotted lanternfly populations affect the amount and type of bycatch in the circle traps? Circle traps were placed on tree-of-heaven at 45 sites throughout the Philadelphia Metropolitan Area and samples were collected three times throughout the summer and fall of 2021. For each sample, SLF and bycatch were identified down to order and counted. Using these data, we summarize the non-target counts and evaluate the variation across traps to non-target insects.The results inform about patterns across the invasion range in Pennsylvania and New Jersey.

Results/Conclusions

Of 132 circle trap samples, bycatch were identified to 15 distinct orders. The most common orders were Hymenoptera and Diptera, which made up 60% and 19.5% of total bycatch, respectively. Hymenopterans and dipterans may be more likely to get caught in circle traps due to their affinity and ability to use SLF honeydew as a resource. However, a total of 7,326 hymenopterans and 2,392 dipterans were captured compared to over 49,000 SLF suggesting the circle trap is effective at catching SLF and minimizing non-target organisms. As the relative abundance of SLF increased, bycatch decreased. This relationship could indicate that SLF are outcompeting other insects for space on tree-of-heaven. These results have broader implications on the importance of documenting bycatch, SLF interactions, and the use of the circle trap to curb SLF populations and reduce harm to other individuals.