Project Overview

Reports

Commodities

Target Pests

Practices

Over the past decade, several hornet species (genus Vespa), have been introduced outside their native range from Europe and Asia. Many species of Vespa are known to be predatory eusocial wasps that prey on a wide variety of insects, including other social hymenoptera like paper wasps and honey bees. In 2016, the greater banded hornet (GBH), Vespa tropica, was first detected in Guam after the accidental discovery of two nests. This newly invasive hornet poses threats to Guam’s agriculture and apiculture industries, as well as human health due to the stinging attacks. Since 2016, there have been numerous reports from island beekeepers that the hornets attack honey bee in large numbers, which has resulted in losses of multiple colonies. Due to the current distribution of GBH, and the lack of effective resources to combat the hornets, GBH could become permanently established in Guam. The establishment of GBH could have a significant impact on Guam’s agriculture and apiculture industries, especially because there are no effective tools to manage the hornets.

There is a serious need for an effective GBH trapping program in Guam, which could take several years and a significant amount of money to develop. The goal of this one-year project is to jumpstart this development of GBH trapping tools by 1) conducting field tests of known and experimental traps and attractants and 2) beginning research into GBH pheromones. The preliminary data collected from this project will also be used to develop a larger grant proposal that can continue to fund our research and help us meet the longer-term goals of GBH management on Guam.

Objective 1: Determine efficacy of existing semiochemicals and trap types for GBH. Current GBH survey methods in Guam are utilizing traps baited with orange juice and rice wine, which has been reported to attract other Vespa species. Unfortunately, this generic bait has not been effective for GBH in Guam, and it can attract other insects, resulting in large numbers of unwanted bycatch such as fruit flies or native insects. This one-year project will take advantage of existing research on known vespid attractants and traps and will incorporate semiochemicals identified from hornet food sources to jump start research into effective lures for GBH. This objective will be completed by the end of the project, although additional surveys may be conducted in following years to improve lure and trap efficacy.

Objective 2: Collect, isolate, and identification of putative pheromones. In parallel to the trapping study, an initial study to identify pheromones of GBH will be conducted. There are three categories of pheromones that should be investigated to create species-specific pheromone lures: alarm pheromone (used to recruit workers to assist with attacking/stinging an identified threat), marking pheromone (used to recruit workers for an attack on nests of prey insects), and queen pheromone (used to attract males from other nests to mate). We will conduct “proof of concept” field bioassays with dissected venom glands and swabbed gland samples to demonstrate the attractiveness of queen and alarm pheromones to conspecifics. Preliminary chemical analyses on the pheromone sources will be done to identify structures of the putative pheromones. Serrano is currently working on the identifications of the alarm and marking pheromones for NGH, which could help expedite the discovery of GBH pheromones if both species use the same or similar compounds. The information obtained from this objective will also serve as preliminary data to help develop new species-specific lures, thus providing another tool for GBH management.

Data that is generated from both objectives will provide a shorter and/or more targeted list of lures and traps to field test in subsequent years. This data will also be used for a grant proposal to USDA NIFA Specialty Crop Research Initiative (SCRI) to support studies needed to further develop a GBH trapping system for Guam.