Methyl Bromide As a Quarantine Treatment For

International Plant Protection Convention 18_TPPT_2016_Sep Reference: Barak et al, 2009 Agenda item: 11

METHYL BROMIDE AS A QUARANTINE TREATMENT FOR

CHLOROPHORUS ANNULARIS (COLEOPTERA: CERAMBYCIDAE) IN RAW

BAMBOO POLES

Barak et al, 2009 COMMODITY TREATMENT AND QUARANTINE ENTOMOLOGY Methyl Bromide as a Quarantine Treatment for Chlorophorus annularis (Coleoptera: Cerambycidae) in Raw Bamboo Poles

ALAN V. BARAK,1 YANG WEIDONG,2 YU DAOJIAN,2 JIAO YI,2 KANG LIN,2 CHEN ZHILIN,2 2 3 LING XINGYUAN, AND ZHAN GUOPING

J. Econ. Entomol. 102(3): 913Ð920 (2009) ABSTRACT At least 26 different species of insects of quarantine signiÞcance were intercepted from 1985 to 2005 on bamboo (Bambusa spp.) garden stakes from China. Three Þfths of the live insects were cerambycids in nine genera, including Chlorophorus annularis F., the bamboo borer. The current APHISÐPPQ treatment is fumigation schedule T404-d, which requires high doses of methyl bromide (MeBr) for 24 h. No speciÞc fumigation data exist for C. annularis. Chinese and American quarantine scientists cooperated in testing to determine whether this schedule, or lower doses, would be effective as a quarantine treatment for C. annularis infesting dried bamboo poles. A lower dose based on APHIS tests for solid wood packing (SWP) failed (3/511 survivors) at 56 g/m3 for 24 h at 10.0ЊC. We therefore tested Þve progressive doses at Þve temperatures intermediate between the lower SWP schedule and the much higher applied doses (e.g., 120 g/m3 for 24 h at 10.0ЊC) of schedule T404-d. Fumigations of infested bamboo poles conducted in 403.2-liter chambers with 52% vol:vol loading at doses of 48, 64, 80, 96, and 112 g/m3 at 26.7, 21.1, 15.6, 10.0, and 4.4ЊC, respectively (20 total replicates, with 4 replicates per dose), had no survivors among 2,847 larvae, 140 pupae, and 122 adults. Control replicates (three) had a total of 455 live stages (397 larvae, 31 pupae, and 27 adults). Tests conducted with a sea/land cargo container loaded to 80% capacity with bamboo poles veriÞed the ability of the schedule to maintain effective concentrations over 24 h in commercial-sized fumigations. We propose a new bamboo quarantine treatment schedule at reduced rates of applied MeBr.

KEY WORDS Chlorophorus, Bambusa, fumigation, quarantine, methyl bromide

The bamboo borer, Chlorophorus annularis F. (Co- Health Inspection Service (APHIS; Anon. 2005a), by leoptera: Cerambycidae), is of particular interest, not Smuggling Interdiction and Trade Compliance only because it may infest U.S. bamboo (Bambusa (SITC) Emergency Action NotiÞcation (EAN) spp.) and related species, but also because it has been (Anon. 2005b), and through determinations of live found in imported garden stakes that would carry a pests on products already distributed to locations in signiÞcant risk of potentially aiding the spread of the the United States. Three Þfths of the live insects were beetle as well as putting it in proximity to possibly long horned beetles (Cerambycidae) in nine genera, susceptible host material (Auclair and Kubilis 2006). including Chlorophorus spp. At least 12 other subfam- In addition, at least 26 different species of live insects ilies or genera were identiÞed in 13 different families of quarantine signiÞcance were intercepted from 1985 including Bostrichidae. Thus, bamboo is a potential through 2005 on dried bamboo garden stakes from source for the introduction of numerous pest species. China (Auclair and Kubilis 2006). Detections were Up to 1994, as many as 400 insect species that damage made by inspectors at U.S. ports of entry: U.S. De- trees and shrubs have been introduced into the United partment of Agriculture (USDA) Animal and Plant States (Haack and Byler 1993, Mattson et al. 1994), primarily as a result of shipping commercial goods in This article reports the result of research only. Mention of a pro- container-based trade. prietary product does not constitute and endorsement or a recom- According to Weidner (1982), C. annularis is nor- mendation by the USDA for its use. mally univoltine, but with drying bamboo, develop- 1 Corresponding author: USDAÐAPHISÐPPQ, Pest Survey, Detec- ment may be extended 1 or more yr. Eggs are long and tion and Exclusion Laboratory, Building 1398, Otis ANGB, MA 02542Ð 5008 (e-mail: [email protected]). oval and are laid in clusters of Ϸ10Ð30 on air dried 2 Animal and Plant Inspection and Quarantine Technical Center, bamboo. The adult is 9.5Ð17.0 mm long and is densely Shenzhen Entry-Exit Inspection and Quarantine Bureau of P.R. clothed in yellowish pubescence. The elytra have dark China, Inspection Building, No. 2049 Heping Rd., Shenzhen 518010, brown or black markings (Fig. 1a). Larvae burrow China. 3 Chinese Academy of Inspection and Quarantine Science, Building under the epidermis, lengthwise, with tunnels densely 241, Huixinli, Huixin Xijie, Chaoyang District, Beijing 100029, China. packed with frass (Fig. 1b). There are Þve larval in-

0022-0493/09/0913Ð0920$04.00/0 ᭧ 2009 Entomological Society of America 914 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 102, no. 3

Fig. 1. (a) C. annularis adult on hand. (b) C. annularis larva in bamboo. (c) Container packed with bamboo poles prepared for fumigation at 80% load factor with center-load sample line. (d) Injection wand method of administering MeBr dose to closed cargo container through door seals. stars, and mature larvae (14.7Ð20.8 mm in length) failed fumigations conducted during the progress of overwinter. Pupation occurs near the surface, with studies in China and in previous in-house tests. There emergence from May to September. In South China was a need for scientiÞc data to support quarantine (Shenzhen, Guangdong Province), the greatest emer- treatments, especially with worldwide desire to elim- gence of adults occurs during May and June. inate or reduce MeBr use as a quarantine treatment In China, near Hong Kong, the beetle “is found because of its ozone depletion potential. MeBr is cur- boring in dead stems where larvae eat out the nodes rently regulated internationally through acceptance and emerge through small holes at intervals along the stem.” Reported host plants include Bambusa spinosa, B. chungii, and Phyllosstachys pubescens. (Hill et al. 160 1982). 144 PPQ T404-d Chlorophorus annularis is widespread in China and 128 Reduced T404-d Southest Asia (Anon. 1992, Xiao 1992) and damages 112 Proposed ISPM-15 bamboo in Fujian, Zhejiang, and Guangdong Prov- 96 inces of China (Qian 1991). The reported distribution 80 is as follows: China (Hainan Island, Koon 1999; Hong Kong area, Hill et al. 1982; northeast China, Koon 1999; 64 south China, Hill 1983; Taiwan, Koon, 1999, Makihara 48 et al. 1989); India (Assam, Punjab) (Duffy 1968, Koon 32 1999); and Indonesia (Java, Sumatra) (Duffy 1968). g / cu. Meter Dose Applied 16 USDAÐAPHISÐPPQ (Plant Protection and Quaran- 0 tine) has in place Schedule T-404d (Fig. 2) for the 0 5 10 15 20 25 30 methyl bromide (MeBr) fumigation of bamboo in con- Fumigation Temperature °C tainers for wood-boring insects (Anon. 2004). PPQ Fig. 2. Relation of proposed ISPM Rule 15 doses for ALB, wood packing fumigation schedules for phosphine and proposed doses for C. annularis, and currently used PPQ sulfuryl ßuoride were recently rescinded because of T404-d MeBr fumigation schedule for wood borers. June 2009 BARAK ET AL.: METHYL BROMIDE TREATMENT FOR INFESTED BAMBOO POLES 915 of the Montreal Protocol of 1998 (UNEP 1998) and Table 1. Composition of replicates of bamboo (Bambusa spp.) through the International Standards for Phytosanitary used in fumigations in 403.2-liter glass fumigation chambers Protection (ISPM) Rule 15 () with regard to solid Fumigation parameters Bamboo weight Representative mean wood packing material (SWPM). (kg Ϯ SEM) load factor percent The presence of two insect species of quarantine Applied Target (mean of four V/V (range, four signiÞcance, the other being Heterobostrychus aequalis dose (g/m3) temperature replicates) replicates) Waterhouse (Bostrichidae), caused this commodity to 48 26.7ЊC 46.3 Ϯ 0.13 52.5 (52Ð54) be considered high risk, thus requiring mandatory 64 21.1ЊC 46.10 Ϯ 0.07 52.5 (52Ð54) fumigation treatment. We report here a series of fu- 80 15.6ЊC 45.88 Ϯ 0.09 52.5 (52Ð54) 96 10.0ЊC 45.05 Ϯ 0.41 52.5 (52Ð54) migations to determine the effectiveness of a fumiga- 112 4.4ЊC 43.20 Ϯ 0.49 52.5 (52Ð54) tion schedule previously recommended for wood boring beetles in SWPM (Barak et al. 2005, 2006) for C. Fumigations were conducted during Jan.-Feb. and May 2008 in annularis in bamboo or to develop a fumigation sched- Shenzhen, China. ule as effective, or at lower doses than APHIS, PPQ T404-d, at several temperatures. infested bamboo along with the pieces with inserted larvae were added to each chamber to give a typical Materials and Methods load factor of Ϸ52% and were essentially similar in Bamboo infested with C. annularis was obtained weight (Table 1). Loading factor was determined by locally in Shenzhen from construction sites, where measuring the circumference and length of four rep- dried bamboo poles have a high risk of infestation and licate bundles and calculating volume. Internal bam- reinfestation by natural populations of C. annularis. boo temperatures for each replicate were monitored The bamboo was divided into piles of small, medium, by inserting a type T thermocouple into a hole drilled and large diameter. Small pieces were ϳ4 cm and large into the center of the thickest wall of a large piece, as much as 8 cm in diameter. The bamboo was cut to which was plugged with electricianÕs putty. When the length (Ϸ116 cm) to Þt the fumigation chambers. bamboo reached the desired temperature, the cham- Certain pieces with good indication of high infestation ber lids were put on, and the vacuum was tested. were set aside to be selectively added to the typical The fumigant doses were computed volumetrically batches of bamboo to increase insect numbers within by calculating the volume of the required grams of a replicate. The typical replicate used 57Ð60 individual MeBr gas after compensating for ambient pressure and bamboo stems. Replicate batches of bamboo to be temperature according to the “ideal gas law” (V ϭ fumigated were weighed and separated in bags for nRT/P). The MeBr was transferred to 10- or 22-liter temperature conditioning and temporary storage. In gas bags (Calibrated Instruments, Hawthorne, NY) addition, two pieces of bamboo with intact internodes, using a 2-liter gas-tight syringe (Hamilton, Reno, NV) free from cracks and splits, were artiÞcially infested from a reservoir bag to a dose bag through a three-way with Þeld-collected larvae by drilling a small hole in valve (The Swagelok Company, Solon, OH). To in- each internodal cavity, inserting one larva, and taping troduce the fumigant to the chambers, a slight vacuum the hole with gas proof tape. This produced a situation was created with a vacuum pump and measured with in which fumigant gas would need to entirely pene- a digital manometer (Dwyer Instruments, Michigan trate the bamboo walls to the interior, thus potentially City, IN) until pressure was Ϸ20Ð32 mmHg below reducing the exposure of the larvae to fumigant gas. ambient atmospheric, enough to accommodate the gas Fumigations were conducted in four 403.2-liter volume plus an additional 10 mmHg to speed gas chambers constructed of tempered glass of Ϸ8.0 mm infusion. The gas bag was attached, and the valve was thickness, which measured 0.56 m high by 0.6 m wide opened, thus allowing the gas to quickly ßow into the by 1.2 m long internally. Each chamber end was Þtted chamber. After all gas was infused, the valve was left with two Ϸ6.35-mm (0.25 in) brass ball valves with open only long enough to equalize the remaining hose barbs, used to draw a vacuum, introduce the pressure differential. The concentration ϫ time value fumigants, and to monitor concentrations. Three ad- (CxT) was computed for each fumigation. ditional brass 0.25-in (6.35 mm) Swagelok compres- Fumigant concentrations in the test chambers were sion Þttings were added to provide access for ther- monitored at intervals of 5 min and 0.5, 1, 2, 4, 8, and mocouple wires and electricity to the small 220-V 24 h after gas introduction, using a Spectros Instru- equipment ventilation fans inside the chambers to ments infrared MeBr monitor (Spectros Instruments, facilitate gas circulation. Hopewell, MA) The instruments were calibrated All chambers were previously tested for tightness against a standard gas mixture made to a concentration by drawing a differential pressure of about Ϫ50 mmHg of Ϸ60 g/m3 MeBr. Accuracy was tested in the labo- and observing a decrease no greater than to Ϫ25 ratory and found to be typically within 1% from 20 to mmHg in at least 1 min. The ability to hold vacuum was Ͼ400 g/m3. essential for infusion of the dose and maintaining the Initial fumigations were begun at two doses (48 fumigant concentration. g/m3 at 21.1ЊC and 56 g/m3 at 15.6ЊC) known to kill the The four chambers were kept in a 6.1-m-long re- wood boring cerambycid A. glabripennis, in solid Popu- frigerated marine cargo container capable of holding lus spp. wood in experiments conducted previously in a set point of Ϯ0.1ЊC. To conduct a fumigation, the Lanzhou, China, during 2002Ð2003 (Barak et al. 2005, 916 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 102, no. 3

a 128 b 144 128 112 4.4 C° 112 g/m3 Dose 112 g/m3 112 96 10.0° C 96 g/m3 Dose 96 g/m3 15.6° C 80 g.m3 96 Dose 80 g/m3 80 21.1° C 64 g/m3 80 Dose 64 g/m3 64 26.7° C 48 g/m3 64 48 48 32 g/cu. Meter MeBr 32

16 16 Average Concentration g/m3 Concentration Average 0 0 04812162024 0 4 8 12162024 Elapsed Time in Hours Elapsed Time in Hours c 1,300 d 1,300 1,200 1,200 Dose vs. CxT 52% Load Real Data Avg. Dose vs. CxT 83% Load 1,100 1,100 T404-d Derived Avg. 1,000 1,000 900 900 800 y = 10.45x 800 R2 = 0.98 700 700 600 y = 10.17x

24 CxT, hr g-h/cu. Meter 600 24 Hr CxT,g-h/cu. Meter 500 R2 = 0.99 500 400 40 48 56 64 72 80 88 96 104 112 120 48 56 64 72 80 88 96 104 112 120 Applied Dose g/cu. Meter MeBr Applied Dose g/cu. Meter MeBr Fig. 3. (a) Average sorption curves for bamboo at Þve temperature and doses, with a 52% loading factor. (b) Sorption curve at 15.6ЊC, with four doses and an 83% loading factor. (c) Relation of CxT products with 52 compared with 83% loading factor. (d) Comparison of average CxTÕs calculated from replicated real bamboo fumigation with 52% load factor, with CxTÕs derived from minimum concentrations as a percent of applied doses from T404-d schedule, at the Þve doses tested.

2006). Based on results of these initial fumigations, the gation and allowed to naturally warm to 26Ð27ЊC be- Þnal conÞrmatory fumigations were conducted at fore the fumigation. These fumigations were con- doses of 48, 64, 80, 96, and 112 g/m3 at temperatures ducted in the chambers in an air-conditioned room. A of 26.7, 21.1, 15.6, 10.0, and 4.4ЊC, respectively, with a batch of bamboo of similar weight served as the con- loading factor of 52% vol./vol. (Fig. 2). Because the trol. Four replicates were fumigated. sorption characteristics were similar at all tempera- After fumigation, and after 2Ð3 h of aeration, the tures, we also tested sorption and periodic concen- bamboo was placed, by replicate, into woven polypro- trations with a higher load factor of 82% at one tem- pylene bags for a postfumigation holding period of 4Ð5 perature, 15.6ЊC, at four doses (64, 80, 96, and 112 d. After this time, the bamboo was carefully split by g/m3), with one replicate each because of limited hand, and all stages found were counted and evalu- bamboo material of good quality. ated. Larvae were considered dead if they were limp Ambient outdoor temperatures during the work and had no movement. Larvae that were turgid or had during 11 January to 3 February 2008 ranged between body movement were considered as alive. We did not Ϸ8 and 12ЊC, so that insects were acclimated to cooler conduct egg fumigations, because the work of Oogita temperatures. To increase cold acclimation and po- et al. (1998) indicated that naked eggs of two common tentially increased insect tolerance to fumigation, bags wood-infesting cerambycids (Callidiellum ruﬁpenne of prepared replicates were held in the refrigerated Motschulsky and Monochamus alternatus Hope) were container so that they were subject to the next lower susceptible to MeBr at low levels from 5 to 15 g/m3 for fumigation temperature for an additional 2Ð4 d. 24 h and that larvae, not adults, were the most tolerant Additional fumigations at a higher temperature stage tested. Furthermore, the eggs of C. annularis are (26.7ЊC, 48 g/m3, 24 h) were similarly conducted dur- fragile, being laid naked on the surface or in cracks of ing May 2008, during which time temperatures were bamboo, thus being more susceptible to fumigation warmer and pupae naturally would be found, although and also not likely to survive commodity handling or pupae are less tolerant than larvae. The bamboo was commerce. stored in a cold room at Ϸ7Ð8ЊC to prevent premature Bamboo moisture content was determined from adult emergence, until near fumigation time. The taking 24 crosscuts from the centers of randomly se- bamboo was removed from storage 4 d before fumi- lected pieces of representative sizes (mean circum- June 2009 BARAK ET AL.: METHYL BROMIDE TREATMENT FOR INFESTED BAMBOO POLES 917

128 for forming into 138 bundles, as well as 90 bundles of poles of 1 m length. The container was loaded to Ϸ80% 112 g/m3 MeBr at Five Rates 48 g/m3 64 g/m3 of its internal height. The container had an internal 3 3 96 80 g/m3 volume of 33.2 m ; therefore, Ϸ26.6 m of bundled 80 96 g/m3 bamboo with a combined weight of 3,900 kg was 112 g/m3 loaded into the container. The weight to volume ratio

MeBr MeBr 64 3

3 was therefore 117.47 kg/m compared with 112.37 48 kg/m3 volume with the small chamber tests. Gas sam- 32 ple lines (6.35 mm OD and 4.8 mm ID polyethylene) Avg. g/m were placed in three locations within the Þlled con- 16 tainer, following traditional recommendations (front- 0 high, center-middle of load, and low-back near the 0 6 12 18 24 ßoor). A large electric fan of Ͼ33-m3/min capacity Elapsed Time in Hours was placed on top of the load near the back doors to maximize MeBr circulation. The sample lines and fan 1800 cord were set in a small quantity of putty and placed 24-hr CxT at Five Doses through the door frame, and the doors were closed. 1500 This formed a tight seal of the door gasket around the Dose vs. CxT lines. The lines terminated at a monitoring station Ϸ10 1200 m from the container. Air vents were sealed with tape. 3 MeBr was applied from a pressurized cylinder using y = 14.214x 900 R2 = 0.9861 the Methyl Bromide Carburetor, which is a micropro- cessor-controlled digital applicator/scale combina- tion with an electrically heated, oil-Þlled volatilizer CxT g-h/m 600 (Guangzhou Import & Export Commodity Inspection 300 Technology Institute, Guangzhou, China). Desired 32 48 64 80 96 112 doses were entered into the digital control panel, Applied Dose g/m3 which automatically opened and closed an electronic valve once the desired amount of gas was dispensed Fig. 4. Sorption curves and accumulated CxT exposure from the cylinder. The volatilizer was preheated to for bamboo poles fumigated at Þve doses over a 24-h period. 90ЊC before gas introduction. A gas introduction line Bamboo was fumigated in a standard height 6.1-m (standard, attached to the volatilizer outlet, Þtted terminally with 20 ft) cargo container loaded to 80% height with cut and bundled bamboo poles. a small diameter metal wand, was used to inject the MeBr between the door seals just behind the fan (Fig. 1d). Fumigations were conducted at ambient temper- ference, 17.92 Ϯ 0.98 [SEM] cm; mean length, ature (27Ð32ЊC) at doses of 48, 64, 80, 96, and 112 g/m3. 116.22 Ϯ 0.096 cm; mean wet weight, 0.91 Ϯ 0.095 kg). The end of the introduction was considered the start Wet basis moisture content was determined according time of the fumigation. MeBr concentrations were to ASTM test method D-4442-92 (ASTM 1992). monitored with all three sample lines after 5 min and A series of commercial-sized fumigations were also at 0.5, 1, 2, 4, 8, and 24 h after introduction. After 24 h, conducted in a new 6.1-m-long standard height gen- the container was opened and aerated continually for eral cargo container Þlled with bamboo poles (Fig. 1c at least 24 h, after which there was no detectable MeBr and d). The purpose was only to conÞrm that efÞca- through the middle-load sample line. The container cious periodic concentrations could be maintained was readied for fumigation at the next higher dose. with Chinese commercial fumigation techniques in a Results were tabulated and displayed with Mi- container in good condition. We purchased a quantity crosoft Excel (Anon. 2000), and statistical analysis of similarly sized bamboo poles from a local bamboo (means and SEM) was performed using Statistix 8 market and cut the poles into lengths of 3.0 and 2.5 m (Analytical Software, Tallahassee, FL).

Table 2. Periodic methyl bromide concentrations obtained at ﬁve temperatures and ﬁve doses during 24-h fumigations of bamboo stakes in 403.2-liter glass chambers

Fumigation parameters MeBr concentration ͓mean (SEM)͔ at time from start loading factor 52% vol./vol. Concentration Bamboo Applied time product Њ Target temperature 3 temperature ( C) dose 0.5 h 1 h 2 h 4 h 8 h 24 h (g-h/m ) (mean Ϯ SEM) (mean Ϯ SEM) (g/m3) ͓mean (SEM)͔ 26.7ЊC 48 38.43 (0.45) 33.15 (0.09) 28.58 (0.23) 24.45 (0.21) 20.83 (0.37) 15.75 (0.26) 503.1 (7.04) 26.3 Ϯ 0.12 21.1ЊC (20.94 Ϯ 0.054 ЊC) 64 49.53 (1.10) 42.03 (1.06) 35.63 (1.090) 30.65 (1.01) 26.75 (0.89) 21.73 (0.70) 653.9 (20.40) 20.9 Ϯ 0.05 15.6ЊC (15.58 Ϯ 0.043ЊC) 80 69.03 (0.59) 55.88 (1.36) 46.63 (1.24) 39.0 (1.40) 33.28 (1.21) 27.1 (0.76) 826.6 (24.57) 15.58 Ϯ 0.04 10.0ЊC (10.27 Ϯ 0.042ЊC) 96 73.05 (3.12) 61.13 (1.84) 53.68 (2.26) 45.2 (2.14) 38.13 (1.82) 29.7 (1.32) 930.0 (40.97) 10.3 Ϯ 0.04 4.4ЊC (4.84 Ϯ 0.064ЊC) 112 93.05 (2.8) 78.2 (2.36) 66.68 (2.12) 55.0 (1.43) 47.4 (1.04) 37.55 (0.59) 1162.6 (25.48) 4.8 Ϯ 0.06

There were four replicates at each concentration. Fumigations were conducted during Jan.-Feb. and May 2008 in Shenzhen, China. The CxT was calculated from the concentrations below. 918 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 102, no. 3

Table 3. Periodic methyl bromide concentrations obtained at four doses at 15.6°C during 24-h fumigations of bamboo stakes in 403.2-liter glass chambers with an 82% load factor

MeBr concentration at time from start loading Fumigation parameters factor about 82% vol./vol. Concentration time Bamboo temperature 3 Temperature Applied product (g-h/m ) (ЊC) ͓mean (SEM)͔ 0.5h1h2h4h8h24h ͓mean (SEM)͔ dose (g/m3) 15.78ЊC (0.048) 64 59.9 49.8 41.2 33.8 27.9 20.7 688.5 15.7 (0.15) 80 74.9 59.4 48.7 39.9 33.3 25.4 829.8 15.7 (0.06) 96 72.4 63.2 53.5 45.3 39.3 31.3 960.5 16.0 (0.06) 112 102.4 85.6 70.6 58.0 48.3 37.2 1198.8 15.7 (0.02)

There was one replicate at each concentration. Fumigations were conducted during Jan.-Feb. 2008 in Shenzhen, China.

Results and Discussion place rapidly over the Þrst 4Ð8 h. Readings were taken Initial tests, intended to prove the efÞcacy a MeBr after 5 min, but presumably, differences in stack tight- fumigation schedule proposed for inclusion into In- ness, sample lead placement, and fan placement made ternational Plant Protection Convention (IPPC) a 5-min reading variable, and thus these were only ISPM Rule 15 for SWPM developed for Asian long- used to conÞrm successful gas introduction. MeBr horned beetle, were successful at the dose of 48 g/m3 concentrations at sample times starting at 0.5 h are at 21.1ЊC, but at a dose of 64 g/m3 at 15.6ЊC, there were shown in Table 2, along with the calculated CxT values 3/537 larval survivors, which, as a mortality rate of and internal bamboo temperatures. 99.44%, is unacceptable for quarantine consideration. Figure 3b shows a similar sorption curve at 82% For this reason, the entire series of initial doses needed chamber loading compared with 52%. Periodic MeBr to be increased a signiÞcant amount. This was not concentrations were initially higher, presumably be- unexpected, because the previous SWPM fumigation cause of less free headspace, but after 24 h, the Þnal for Asian longhorned beetle (Barak et al. 2005) in- concentrations were similar to those in the chambers volved sawn wood with multiple boring holes and with 52% loading. A comparison of CxT products ob- coarse grain and therefore potentially greater pene- tained with load factors of 52 and 82% (Table 3) tration of the wood compared with the smooth, hard indicated that the sorption as a proportion of dose is epidermal surface of bamboo poles. Figure 2 compares predictable across temperatures and similar in slope the lowest intended initial doses, the current T404-d (Fig. 3c) and that the higher load factor resulted in schedule, and the intermediate schedule we decided slightly higher CxT products most likely caused by less to validate. The subsequent doses were increased by free air volume. 16Ð32 g/m3 from 21.1 to 4.4ЊC, which were still less than the T404-d schedule of 8Ð32 g/m3 from the high The PPQ Schedule T404-d minimum concentra- to lower temperatures. tions were compared with the treatment dose, and this The fumigation parameters for doses chosen for the proportion (concentration as a percent of applied next tests are shown in Table 1. Temperatures were dose) was used to calculate the CxT that would be maintained, and weights were consistent throughout obtained at the applied concentrations we used. These the tests. Moisture content of 24 representative sec- data are presented in Fig. 3d. The CxT data from our tions of bamboo poles was 10.18% wet basis (Ϯ0.102; tests was similarly also plotted, and the result shows range, 9.5Ð11.62%). The rapid sorption of MeBr by that similar sorption curves exist when the CxT de- bamboo is shown in Fig. 3a. The sorption curve was rived from T404-d is compared with our data from similar at the Þve temperatures tested. Sorption took bamboo. These data support the validity of speciÞed

Table 4. Results of methyl bromide fumigation of bamboo garden stakes at ﬁve temperatures and doses for 24 h

Fumigation parameters Chlorophorus annularis larval counts Pupae Inserted larvae CxT Target temerature (ЊC) Applied Larvae Total in 3 (adults) Survivors survivors/live (g-h/m ) (mean Ϯ SEM) dose (g/m3) (mean Ϯ SEM) replicates (alive/dead) (mean Ϯ SEM) 21.1ЊC 128 (single rep.) 0/0 4.4ЊC 0 (controls) 177 (single rep.) 397 397 16/16 10.5 Ϯ 5.5 0 0/0 27.6ЊC 92 (single rep.) Ñ 31/0(27/0) 26.7ЊC (26.33 Ϯ 0.121ЊC) 48 126.5 Ϯ 19.9 506 0 NA 503.1 0/140 21.1 (20.94 Ϯ 0.054ЊC) 64 176.75 Ϯ 8.93 671 0 0/59 14.75 Ϯ 4.85 653.9 0/0 15.6 (15.58 Ϯ 0.043ЊC) 80 147.25 Ϯ 17.0 589 0 0/88 22.0 Ϯ 1.87 826.6 0/0 10.0 (10.27 Ϯ 0.042) 96 123.0 Ϯ 10.6 492 0 0/28 7.0 Ϯ 1.0 930.0 0/0 4.4 (4.84 Ϯ 0.064ЊC) 112 147.25 Ϯ 11.7 589 0 0/25 6.25 Ϯ 0.85 1162.6 0/0 Sum, all temperatures 2,847 (not 0 (not 0/164 (no controls) NA 31/0 controls (less controls) controls) controls) (0/140) test

NA, not applicable. June 2009 BARAK ET AL.: METHYL BROMIDE TREATMENT FOR INFESTED BAMBOO POLES 919

Table 5. Measured concentrations and calculated CxT expo- Table 6. Recommended methyl bromide doses at four tem- sure of methyl bromide during 24-h fumigations of bamboo poles peratures and periodic min. concentrations, for quarantine level in a 6.1-m container at ﬁve doses control of C. annularis F. in bamboo garden stakes

Applied Methyl bromide concentration at time Minimum Accumulated Fumigation dose indicated 3 concentrations CxT (g-h/m ) parameters 3 MeBr exposure (g/m3) (g/m )at 5 min 0.5 h 1 h 2 h 4 h 8 h 24 h (calculated CxT) Fumigation Applied (g-h/m3) 48 66.4 53.4 47.8 42.1 35.8 29.8 20.1 702.3 temperature dose 0.5h2h4h24h 64 79.8 69.1 60.5 53.6 45.7 38.2 27.6 912.1 (ЊC) (g/m3) 80 94.5 84.1 76.5 67.4 58.0 50.5 38.4 1,201.5 96 105.2 92.8 87.6 76.9 66.1 55.7 41.3 1,330.0 26.7 48 39 29 25 16 537 112 127.4 111.0 100.9 87.0 74.3 63.2 53.6 1,565.5 21.1 64 50 36 31 22 690 15.6 80 69 47 39 27 870 The container was loaded to 80% of capacity, 117.47 kg/m3 bamboo 10.0 96 73 54 45 30 985 load factor. All values and CxT are the average of three sample lines. 4.4 112 93 67 55 38 1,223

Observed concentrations were rounded up to nearest whole gram Schedule T404d minimum concentrations compared per cubic meter at the selected times. This CxT was calculated from these values, using the applied dose as beginning time. with our current data. The mortality data from our series of fumigations are shown in Table 4. Although the controls had high numbers of live larvae dissected from untreated bam- high numbers needed to be selected and inserted into boo batches, all treatments had no survivors from a the commercially purchased bamboo used here to total of 2,847 larvae, 140 pupae, and 122 test insects. obtain meaningful numbers. They describe several Three control replicates had high numbers of live situations where population and risk parameters larvae, pupae, or adults (397, 31, and 27, respectively) would require control levels of 99.532 with as few as with little or no natural mortality. Two other beetle 639 insects per test. The numbers of test insects species, both adults and larvae, were sometimes found needed to conÞrm probit-9 or extreme high control is in bamboo samples. All were dead. These were the not practical with species such as C. annularis. In our cerambycid Purpuricenus temminckii (Guerin-Menev- test, with 520 conÞrmed dead insects, the failure to ille) and the bostrichid Bostrychopsis parallela Þnd one survivor could indicate a control level of (Lesne). 99.81%, with the highest count replicate at 99.86%. In The results of the fumigations of a 33.2-m3 cargo total, we had 3,011 recovered dead stages, with no container Þlled with commercial-sized load of bam- survivors. The goal of ISPM Rule 15 is to “reduce the boo poles (Figs. 1c, d, and 4) at the Þve tested doses risk of introduction and/or spread of quarantine pests” are shown in Table 5. All gas sample leads within a and to describe measures that “signiÞcantly reduce the container indicated essentially equal concentrations, risk of pest spread.” We believe this recommended presumably indicating proper fan operation and gas schedule meets that requirement. circulation. In all cases, the periodic concentrations and total CxT product exposure exceeded that of the Acknowledgments small chamber tests. This was in part because of the higher load factor (4.5% greater) in the shipping con- This work was supported by APHIS PPQ CPHST Project tainer compared with the experimental chambers, T7Q02 and Shenzhen Entry-Exit Inspection and Quarantine which restricted the volume of free headspace. Be- Bureau of China (SZ2008020). The authors thank the fol- cause of this success, we propose a treatment schedule lowing people in China for valuable support of this project: C. Zhinan, Z. Guiming, and X. Caiyu of he Animal and Plant with required minimum concentrations at intervals of Inspection and Quarantine Technical Center of Shenzhen 0.5, 1, 2, 4, and 24 h, and the resultant CxT product, Entry-Exit Inspection and Quarantine Bureau (Shenzhen suitable for bamboo borer in bamboo poles, as de- CIQ), C. Xinru from Shekou CIQ, and Prof. W. Yuejin of the scribed in Table 6. The proposed schedule has signif- Chinese Academy of Inspection and Quarantine Science, icantly lower applied doses of MeBr than the current Beijing (CAIQ). We also thank the following for commen- T404-d and will result in large reductions in the use of tary and review of the manuscript: S. Myers, PPQ, Otis MeBr. Reduction of MeBr use would amount to Ͼ584 PSDEL, Otis ANGB, MA, and J. Leesch, USDAÐARS, Parlier, kg/1,000 fumigations of 6.1-m-long standard height CA. containers, provided the fumigations were distributed across all Þve doses equally. References Cited The probit-9 standard for quarantine efÞcacy (99.99683%) was developed for tropical fruits with Anon. 1992. Iconography of forest insects in Hunan, China. heavy infestations of fruit ßies (Follett and McQuate, Science and Technology Press, Hunan, China. 2001). They also propose that these standards may be Anon. 2000. Microsoft excel. Microsoft, Redmond, WA. Anon. 2002. International standards for phytosanitary mea- too high for situations of lower risk and less abundant sures. Guidelines for regulating wood packaging material populations. The bamboo borer, as well as possibly in international trade. FAO, Rome, Italy. other wood-boring Cerambycids, Þt this situation, be- Anon. 2004. USDAÐAPHISÐPPQ treatment manual. Sched- cause it was difÞcult to obtain large numbers of test ule T-404, wood products including containers as such. subjects, and hand-selected sticks of bamboo with USDAÐAPHISÐPPQ, Frederick, MD. 920 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 102, no. 3

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