COLLEGE OF CO MPUTER, MATHEMATICAL AND NATURAL SCIENCES

DEPARTMENT OF ENTOMOLOGY 4112 Plant Sciences Building College Park. Maryland 20742-4454

301.405.3911 TEL 301.314.9290 FAX www.entomology.umd.edu

January 26, 2012

Dr. Russell Wasem Chemical Review Manager Hexaflumuron Registration Review

Pesticide Re-Evalua tion Division (PRD) U.S. Environmental Protection Agency

Dear Dr. Wasem:

I have been consulting with Dow AgroScie nces on honey bee exposure issues and have been asked specifically to assess the potenti al threat of the Hex-Pro Termite Baiting System to Apis and non- Apis species. As you may know, I am not a termite expert but one of my current research areas addresses exposure risks and sub-lethal effects of pesticides on honey bee health. So I feel conf ident about reviewing this issue and offering an unbiased assessment. To actually see the baiting system in application, Ms. Jessi McKinney, Dow’s regional technical representa tive, arranged a field visit in December to a treated site, where I examined the placem ent of the in-ground and above-ground HexPro products, and discussed their uses w ith Mr. Wayne White, a certified PCO from American Pest Management Company.

My immediate impression with this baiting syst em is that it ideally represents a remedial IPM approach because the stations baited wi th untreated wood only are used first to monitor for termite activity. If act ivity is detected, the wood is replaced with a bait matrix

of hexaflumuron-treated cellulose. And then after the termite infestation is controlled, untreated wood is again placed in the station to continue monitori ng for re-infestations. As you know, the alternative approach is to apply long-residual insecticides preventatively by soil incorpor ation or soil injection around structures where termites may be active. In my opinion, these altern ative methods pose a gr eater potential for exposure to non-target organisms, including bees, especially b ecause several active ingredients are soil-applied systemics. I br ing up this point because I believe that comparative potential for bee exposure of all control methods available should be considered in your decision.

I reviewed the technical information on the Hex-Pro baiting system and Dow’s rationale statement for a Waiver of Data. With regards to the in-ground application, the bait stationwill not expose bees to the active ingredient hexaflumuron for several reasons. First, the plastic tube that houses the cellulose bait has slots to allow termites to enter. These slots are 2.5 mm wide, which are too small for hone y bees or ground-nest ing native bees to enter the bait tube. The smaller native sp ecies that nest underground in burrow and

tunnels are halictid and andrenid bees, and the smallest species found in the U.S. is 5-6 mm in size. Second, there is no reason why gr ound-nesting bees would be attracted to the bait station as a nesting site or food source. All species that nest in the ground do not utilize wood as a nesting s ite. Third, ground-dwelling bees make nests below ground as a shelter for their offspring. They construct ch ambers at the end of tunnels and provision them with nectar and pollen – food for the be e larvae. Adult bees do not forage in the ground while constructing and provisioning tunn els, and larvae feed exclusively on the provisioned food. Finally, the ne sting biology of the halictid and andrenid bees suggests

that their burrows and tunnels are unlikely to be in areas around structures where bait stations would be placed. Most mining bees prefer areas where vegetation is sparse and

the soil is loose - conditions that are not typical around the foundation of houses and

other structures.

It is my understanding that the above-ground termite baiting system is used primarily inside structures, attached flush with screws to the surface wall where termite activity has

been detected. A common site is the crawl space below s ections of structures where gallery tubes are present and provide a sealed conduit for termites to move from the colony in the ground to the source of wood a bove. The bait station is placed over these galleries and tightly sealed to the surface with a provided gasket and often with the use of caulk. This prevents entry of light whic h would repel termites and thus reduce the efficacy of the bait station. Thus, if prope rly installed, the above-ground bait product will not expose bees because there is no way for bees to gain access to the bait, even if they

were attracted to it.

In short, based on the foraging biology and nesting behavior of bees, and the physical exclusion of the bait stations, I concur with the explanations in Dow’s rationale statement

for a Waiver of Data. Afte r a review of the Hex-Pro Termite Baiting System and having observed its application in the field, I am convinced that this product, whether used in- or above-ground will pose no harm to Apis and non- Apis species. If there is a need to

discuss this issue in more de tail, I can be contacted at galen@umd.edu or 202-812-9828.

Respectfully,

Galen P. Dively

Emeritus Professor/IPM Consultant