Emerald ash borer (Agrilus planipennis Fairemore) (EAB) is native to far eastern Asia, and was accidentally introduced to North America in the mid 1990’s. It was first detected in 2002 in Detroit MI, and has spread to 18 US states and 2 Canadian provinces. North American Fraxinus spp. show little to no resistance to the beetle, allowing it to attack and kill trees regardless of tree condition (Rebek et al. 2008). One major concern has been locating new infestations of EAB. The average time from infestation to detection is 6-12 years (McCullough et al. 2011; MFK unpublished data), ample time for the beetles to become firmly established in a new location. Much research and resources have been devoted to developing survey techniques to shorten the time between infestation and detection (Francese et al. 2006; Poland et al. 2006; Crook et al. 2009; Francese et al. 2011; Grant et al. 2011; McCullough et al. 2011; Ryall et al. 2012).

A novel survey technique called biosurveillance has been developed as part of that effort (Marshall et al. 2005; Careless 2009). This technique takes advantage of the prey specialization of Cerceris fumipennis Say, 1837 (Hymenoptera: Crabronidae: Cercerini), a native solitary digger wasp. As is typical for digger wasps, females provision larval cells with paralyzed prey. A wide range of adult beetles in the family Buprestidae are utilized by Cerceris fumipennis females (Marshall et al. 2005; Careless and Marshall 2010; Rutledge et al. 2011) to provision their nests. Included in that range are beetles in the genus Agrilus, the genus of the EAB. By monitoring the prey returning wasps bring to their nests, surveyors can sample the buprestid beetles in the area surrounding the colony, including EAB. Studies by Careless (2009) suggested that the majority of species in an area are sampled after collecting 50 beetles from a colony, and that further collecting yields diminishing returns. Thus, the goal of an EAB biosurveillance program is to collect at least 50 beetles from each colony (Carrier and Jackson 2012).

Biosurveillance has been undertaken in several states and provinces where EAB is already known to occur and in areas, like New England, where the beetle had not yet been detected (Table 1). In Connecticut, a biosurveillance program was begun in 2008 by The Connecticut Agricultural Experiment Station (CAES) with surveys for Cerceris fumipennis colonies and the monitoring of nest sites, collecting 129 beetles. The program was expanded in 2009 the discovery of 40 additional colonies suitable for monitoring for EAB, biosurveillance of 36 sites and the capture of 315 beetles. To enhance colony survey efforts in Connecticut, a citizen-scientist program was initiated in 2010 modeled on a volunteer program in Maine (Rosenholm 2012; Teerling 2012) called ‘Wasp Watchers’ that assigns volunteers to specific colonies and trains them to monitor the wasps’ prey for EAB. The ‘Wasp Watcher’ program in Connecticut has grown steadily, with 23 watchers in 2010, 29 in 2011 (12 returning) and 52 watchers in 2012 (19 returning), increasing the number of colonies monitored and beetles collected.

In 2010 and 2011, 1, 605 beetles were collected by CAES volunteers and researchers. Maine, Vermont and Massachusetts also have flourishing ‘Wasp Watcher’ programs (Rosenholm 2012). With the detection of EAB in Saugerties, NY in 2010, a collaborative effort between the USDA Animal Plant Health Inspection Service (APHIS), Plant Protection and Quarantine (PPQ) and CAES, with support of the U.S. Forest Service, was made to monitor as many colonies in Connecticut as possible. In 2011 and 2012, USDA-APHIS-PPQ personnel monitored colonies in the four western counties, while personnel from CAES monitored colonies in the four eastern counties, in addition to administering the ‘Wasp Watcher’ program. In the 2012 season, 2, 139 buprestids were collected from 81 Cerceris fumipennis colonies.

Emerald ash borers have been recovered from wasps in several areas with known EAB populations (Table 1), but this approach had not yet made the initial detection of emerald ash borer in a state or province where it had previously been undetected. However, on the morning of July 16, 2012, CAES personnel captured a wasp carrying a female emerald ash borer in the Town of Prospect in New Haven County, CT. A further six emerald ash borers were captured at that colony that same afternoon. Since EAB is a federal and state regulated pest, the USDA-APHIS-PPQ State Plant Health Director submitted the initial specimen to the PPQ identifier, James Zablotny, for identification. James Zablotny confirmed the state identification on July 17, 2012 and forwarded the specimen onto the Systematic Entomology Laboratory (SEL) in Beltsville, MD for confirmation as a new state record. Alexander Konstantinov, SEL, confirmed the identification on July 18, 2012. This represented the first new state detection using Cerceris biosurveillance for the detection of EAB. In subsequent days, an additional 26 EAB adults were captured, including EAB found on the ground near the entrance to nest holes (Fig. 1). As fewer Cerceris fumipennis colonies were being monitored in this area than in other parts of the state, additional colonies were located in Prospect and towns immediately adjacent to it (Beacon Falls, Cheshire, Naugatuck, Bethany, Seymour). Surveys of these colonies yielded two more EAB positive colonies. On July 17^th, three EAB were captured at a Prospect site approximately one km due south of the first find. One additional EAB was caught on July 24^th in the Town of Beacon Falls, about 11 km southwest of the colonies in Prospect. A ‘Wasp Watcher’ volunteer had caught nine EAB at the original Prospect colony in the first week of July, but did not recognize the beetles and so the finds were not reported until July 19^th.

In addition to the three colonies at which EAB were collected, 25 other Cerceris fumipennis colonies had 50+ beetles collected (Table 2A, B). By USDA-APHIS-PPQ criteria, collecting 50 beetles at a site is not an official ‘negative’ for EAB (Carrier and Jackson 2012), but it does suggest EAB is likely not present, or is present at very low densities. The minimum EAB density for Cerceris fumipennis detection is not known, however, we do know that EAB was found at the first Prospect colony after only 15 beetles were collected in 2012. However, that same colony was monitored in 2011, with 68 beetles representing 11 species captured (and no EAB).

As part of Connecticut’s statewide EAB surveillance efforts, USDA-APHIS-PPQ purple-prism traps were deployed around the state in 2011 (940 traps) and 2012 (544 traps) by the University of Connecticut with support from APHIS-PPQ. During routine trap monitoring, suspect specimens were collected from traps in Prospect on June 29^th, 2012 and Naugatuck on July 9^th, 2012 but had not yet been processed when EAB was first collected from Cerceris fumipennis. After confirmation of EAB was received from SEL, the EAB from the Prospect trap was identified by Claire Rutledge, the designated state-identifier, on July 18^th. During the week following the initial find in Prospect, the purple-prism traps in the area were re-checked and additional suspect specimens were collected in Prospect, Naugatuck and Bethany (all New Haven County). Because Bethany and Naugatuck would represent new towns for EAB, the specimens collected from those traps were sent to PPQ identifier Bobby Brown for confirmation of identity, which was received on July 20^th. An additional 29 traps were deployed in Prospect, Cheshire, Naugatuck and Bethany to help further define the extant of the infestation. One of these subsequently deployed traps, across the road from the second positive Cerceris fumipennis colony in Prospect, also captured an EAB (Table 2A, B).

No purple-prism traps outside of the four towns mentioned above captured an emerald ash borer (Table 3). Ash trees with heavy EAB infestations were subsequently found in the Town of Prospect and a state quarantine for New Haven County was established on August 9, 2012 followed by a parallel federal quarantine on September 12, 2012.

Together, biosurveillance with Cerceris fumipennis and use of purple-prism traps provided the first detection of an EAB infestation in Connecticut. Subsequent Cerceris fumipennis colony identification and biosurveillance also provided an initial estimate of its extent. Delimitation surveys for infested trees will continue over the winter by peeling bolts. In summer 2013, multiple Cerceris fumipennis colonies at the known limits of the infestation will be surveyed to further delimit the infestation.