A combination sulfuryl fluoride and propylene oxide treatment for, Trogoderma granarium (Coleoptera: Dermestidae)

Authors: MYERS, SCOTT - Animal And Plant Health Inspection Service (APHIS); GHIMIRE, MUKTI - Animal And Plant Health Inspection Service (APHIS); Arthur, Franklin; PHILLIPS, THOMAS - Kansas State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2021
Publication Date: 6/29/2021
Citation: Myers, S.W., Ghimire, M.N., Arthur, F.H., Phillips, T.W. 2021. A combination sulfuryl fluoride and propylene oxide treatment for, Trogoderma granarium (Coleoptera: Dermestidae). Journal of Economic Entomology. 114(4):1489-1495. https://doi.org/10.1093/jee/toab124.
DOI: https://doi.org/10.1093/jee/toab124

Interpretive Summary: The khapra beetle is the only stored product insect that is subject to quarantine regulations in the United States should it be detected at ports of entry. Current regulations specify fumigation with methyl bromide to eliminate infestations, but alternative fumigants are needed should further restrictions be placed on methyl bromide. We conducted studies by exposing different life stages of the khapra beetle to alternative fumigants sulfuryl fluoride and propylene oxide. The egg stage was by far the most tolerant life stage to both fumigants. Concentration-time dose ranges were developed for both fumigants at concentrations necessary to kill all life stages, including eggs. Results show that both fumigants can serve as alternatives to methyl bromide, and can be used by USDA-APHIS to develop new control programs using these fumigants to disinfest commodities when khapra beetle is detected.

Technical Abstract: Khapra beetle, Trogoderma granarium is an important quarantine pest of stored products. While it is not established in the US, frequent interceptions highlight the need for treatments to eradicate isolated populations if they occur. Methyl bromide has long been the standard fumigant used for this purpose, however increasing restrictions on its use necessitate development of new treatment options. Here we evaluate a treatment for khapra beetle using a combination of sulfuryl fluoride (SF) and propylene oxide (PPO). Experiments were conducted to determine most tolerant stages and the effective rates for each compound. Combination treatments using both products were then evaluated at several temperatures to determine effective doses for quarantine level control. The egg stage was by far the most tolerant to SF requiring concentration × time (CT) products roughly 10-fold greater than the next most tolerant stage, diapausing larvae. Diapausing larvae were significantly more tolerant to SF than non-diapausing larvae in a recently collected ‘field’ strain, but not in 30+ year old ‘laboratory’ culture. PPO treatments were shown to completely control the egg stage at CTs greater than 155 hr-mgL-1 at both 10 and 20°C. Resulting combination treatments with initial dose rates of 96 and 40 mgL-1 at 10°C and 80 and 40 mgL-1 at 20°C are proposed for SF and PPO, respectively. These combination treatments utilize SFs efficacy against the larval stage along with PPOs superior ovidical properties to provide enhanced treatment efficacy over each product alone against all life stages of khapra beetle.