Effectiveness of Sulfuryl Fluoride Fumigation for the Control of Phosphine-Resistant Grain Insects Infesting Stored Wheat.

A field experiment was conducted in eight 13.6-MT steel bins containing 6.8 MT each of wheat to assess efficacy of sulfuryl fluoride or SF fumigant to control phosphine-resistant and susceptible Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst). Approximately 400 adults of each type of beetle were added to each bin. Additionally, muslin bags containing immature stages and adults, with their respective diets, were also placed in bins. Four bins were fumigated with SF and others were untreated control bins. The SF dosages in treated bins ranged from 1,196­1,467 mg-h/liter. Mortality of adults in each bag was assessed 5 d postfumigation; diet minus adults was incubated in a jar, and number of adults counted after 8 wk. No significant change occurred in number of insect-damaged kernels in SF-treated bins. In trier samples from SF-treated bins, R. dominica numbers declined from 24 prefumigation to 0 at 3- and 6-wk postfumigation; T. castaneum numbers were unchanged. In WBII traps from SF-treated bins, numbers R. dominica and T. castaneum declined from 25 and 33, respectively, prefumigation to 0 or near 0 at 3- and 6-wk postfumigation. Mortalities of resistant and susceptible adult R. dominica, and adult and large larvae of T. castaneum in SF-treated bags was 100%. For all four types of beetles, adult numbers in jars associated with SF-treated bins were 0 or near 0. Results show SF is effective against all life stages of phosphine-resistant R. dominica and T. castaneum, and can be used for phosphine resistance management.

Exposure of Brown Recluse and Brown Widow Spiders (Araneae: Sicariidae, Theridiidae) to a Commercial Sulfuryl Fluoride Fumigation.

The body of pesticide research on spiders is sparse with most studies using topical or residual applications to assess efficacy. Data on the effects of fumigation on spider survivorship are scarce in the scientific literature. In this study, we exposed adult male and female brown recluse spiders, Loxosceles reclusa Gertsch & Mulaik, and female brown widow spiders, Latrodectus geometricus C. L. Koch, to a commercial fumigation event using sulfuryl fluoride directed at termite control. General consensus from the pest control industry is that fumigation is not always effective for control of spiders for a variety of reasons, including insufficient fumigant dosage, particularly, for contents of egg sacs that require a higher fumigant dosage for control. We demonstrated that a sulfuryl fluoride fumigation with an accumulated dosage of 162 oz-h per 1,000 ft(3) at 21°C over 25 h (≈1.7 × the drywood termite dosage) directed at termites was sufficient to kill adult brown recluse and brown widow spiders. The effectiveness of commercial fumigation practices to control spiders, and particularly their egg sacs, warrants further study.

Fumigation of bed bugs (Hemiptera: Cimicidae): effective application rates for sulfuryl fluoride.

The bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), has resurged recently as a domestic pest in North America with very limited options for decisive control. We report efficacy studies with sulfuryl fluoride (SF) toward use as a structural fumigant to control bed bugs. Laboratory studies were conducted in which eggs, adults, and nymphs from a pesticide susceptible laboratory population were fumigated for 24 h using SF at 99.8% purity in airtight, 3.8-liter glass containers under two temperatures, 25 degrees C and 15 degrees C. Bed bugs were placed in separate ventilated glass vials and wrapped in mattress padding before fumigation. The gas concentration within each jar was determined using quantitative gas chromatography-mass spectrometry. Dose-response trials using eggs of known age (48-96 h) were conducted at five or six target concentrations measured as concentration x time accumulated dosages (g-h/m3) and one untreated control at each temperature. Each target dose was replicated in four different fumigation containers (replicates), with at least 32 eggs per replicate. The number of hatched and unhatched eggs postfumigation, and number of live and dead nymphs that resulted from hatched eggs, were evaluated daily for at least 1 wk after egg hatch. The lethal accumulated dosage (LAD99) for bed bug eggs was 69.1 (95% fiducial limits [FLs] of 62.9-79.5) g-h/m3 at 25 degrees C and 149.3 (95% FLs of 134.4-177.9) g-h/m3 at 15 degrees C. Confirmatory trials with dosages of 1.5x the LAD99 were conducted at 25 degrees C and 1.5x the threshold mortality dose at 15 degrees C with at least 15 adults, 13 late-instar nymphs and 79 eggs of known age per replicate. At 25 degrees C, a target dosage of 103.7 g-h/m3 resulted in 100% mortality of adults and late-instar nymphs. Nymphs emerged and survived from two of 439 eggs treated with SF dosages that were 6-7 g-h/m3 less than the target dosage. No nymphs emerged from eggs fumigated with dosages > 97.9 g-h/m3 in the validation study. Therefore, the threshold dosage for complete egg mortality (97.9 g-h/m3) was used, rather than the LAD99, to calculate the monitored field dosage rate of 148.2 g-h/m3 (= 1.5 x 97.9 g-h/m3) for control of all life stages of bed bugs at 25 degrees C. Based on these results, at 15 degrees C, 1.5x the threshold dosage for complete egg control (189.7 g-h/m3) was used to calculate a target dosage of 285 g-h/m3 for the confirmatory trial, which resulted in 100% mortality of adults, late-instar nymphs, and eggs.

Sulfuryl fluoride as a quarantine treatment for emerald ash borer (Coleoptera: Buprestidae) in ash logs.

Fraxinus spp. logs infested with Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) were fumigated with sulfuryl fluoride (SF) in 432-liter chambers at 15.6 and 21.1 degrees C for 24 and 48 h. Concentration x time (CxT) exposures (g-h/m3) of SF obtained were 3,382 (24-h exposure) and 5,466 (48-h exposure) at 15.6 degrees C and 3,329 (24 h) and 4,385 (48-h exposure) at 21.1 degrees C after doses of 144, 128, 128, and 104 g/m3, respectively. After aeration, logs were placed in modified fiber drums for 8 wk to capture emerging beetles. No adults emerged from any of the fumigated logs, whereas 933 adults emerged from control logs. Eggs were fumigated at CxT exposures similar to log fumigations (3,240 and 4,262 g-h/m3, respectively) and again at doses 16 g/m3 lower, at 21.1 degrees C for 24 and 48 h. No hatch was observed at CxT dosages > 4,262 g-h/m3. No larvae continued development on artificial diet after hatching from eggs fumigated at all tested dosages, whereas 10 control larvae developed to instar I or II. Chamber fumigations with 31 and 46% load factors provided additional sorption and concentration data. A. planipennis-infested logs in tarped, 149.1-m3 cargo containers were fumigated at dosages used in successful trials. Logs were monitored for 8 wk for adult emergence. There was no adult emergence, but 621 adults emerged from a similar quantity of control logs. CxT dosages of SF for 100% control of A. planipennis at 15.6 and 21.1 degrees C for 24- and 48-h exposure can be obtained under commercial fumigation conditions. A quarantine treatment schedule for SF is proposed.

Efficacy of Sulfuryl Fluoride Against Fourth-Instar Pecan Weevil (Coleoptera: Curculionidae) in Pecans for Quarantine Security.

The efficacy of sulfuryl fluoride was evaluated for control of fourth-instar pecan weevil, Curculio caryae (Horn), at 25°C for a 24-h exposure. Larvae, collected as they naturally emerged from pecans, were used to artificially infest pecan nuts. Infested nuts were fumigated with six concentration by time (CT) treatment dosages of sulfuryl fluoride (0-750 g-h/m3) within air-tight, glass containers. The sulfuryl fluoride concentration in each fumigation container was analyzed 30 min after sulfuryl fluoride introduction and just prior to termination of the experiment. Mean sulfuryl fluoride CT dosages were calculated from sulfuryl fluoride measurements and were used for probit analysis. The lethal accumulated dosage (LAD99) of sulfuryl fluoride for pecan weevil was 1052.0 g-h/m3 with a 95% C.I. of 683.21-2,573.0 g-h/m3. For the confirmatory trial, we used two sulfuryl fluoride CT dosage treatments, 1,100 and 1,300 g-h/m3, and a nonfumigated control. All larvae were dead in both fumigation treatments by 14-d postfumigation. Due to higher mortality in the nonfumigated control in the confirmatory trial compared to that of the dose-response trial, 1300 g-h/m3 was selected as the sulfuryl fluoride CT dosage for a proposed quarantine treatment schedule. Fumigating pecans with sulfuryl fluoride can control larval pecan weevil infestations in commercially traded nuts and maintain compliance with quarantine regulations both within and outside the United States.