Confidence Limits and Sample Size in Quarantine Research

Couey, H. Melvin; Chew, Victor

doi:10.1093/jee/79.4.887

Cited by 143 publications

(27 citation statements)

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“…Table 1 lists the projected exposures, ( Ct ) p , to cause a specified percentage mortality in the treated population, a , in this case 95%, 99%, and 99.9968% (respectively, LE 95 , LE 99 , and LE P9 ) and the corresponding estimates of the bounds [upper (UL) and lower (LL) limits] at the 95% confidence level (CL). Probit 9 (P9) projections, where a = 99.9968% mortality, 43 are often prone to bounds that span an order of magnitude, or greater, which can decrease confidence in the utility of probit analysis. Moreover, it is difficult to confirm probit 9 projections when test insects are difficult to rear in numbers approaching 100 000, such as the case for BMSB (diapausing and nondiapausing).…”

Section: Resultsmentioning

confidence: 99%

Ethyl formate dilution in carbon dioxide for fumigation control of the brown marmorated stink bug Halyomorpha halys, Stål (Hemiptera: Pentatomidae)

Kawagoe

Abrams

Lourie

et al. 2022

Pest Management Science

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BACKGROUND The brown marmorated stink bug (BMSB), Halyomorpha halys, has caused significant agricultural damage to numerous hosts, so agricultural producers seek to limit its spread. Where established, BMSB can also cause substantial urban and commercial disturbance, as overwintering adults may seek refuge inside dwellings, covered spaces, vehicles, and consignments. Phytosanitary authorities are most concerned with the importation of ‘hitchhiking’ adults in this refugia, with certain countries requiring a quarantine treatment to mitigate risk. This study explores fumigation with ethyl formate, applied as 16.7% by mass dilution in carbon dioxide, for control of adult BMSB. RESULTS The induction of diapause, to simulate overwintering physiology, resulted in 2‐ and 3‐fold increases in the tolerance of adults toward this ethyl formate fumigation at 10 ± 0.5 °C (truex¯±2s) lasting for 8 and 12 h, respectively. However, a decreased tolerance (0.7‐fold) of diapausing specimens was observed for a 4‐h duration. Diapausing and nondiapausing adult BMSB can be controlled at the probit 9 level if the headspace concentration of ethyl formate, [EF], in the carbon dioxide mixture is maintained ≥7.68 mg L−1 for 12 h at 10 ± 0.5 °C (truex¯±2s). If the duration is shortened to 4 h, [EF] must be maintained ≥14.73 mg L−1 over the course of fumigation. CONCLUSION The toxicity of ethyl formate in this mixture can be distinct for different physiological states of the same life stage, as evidenced by a ca. 3‐fold increase in the Haber's z parameter for adult BMSB when in diapause. Respective to the physiological state of adults, this study identifies how the applied dose and/or treatment duration can be modulated (i.e. tuned) to ensure adequate toxicological efficacy toward BMSB infesting hosts or refuge at temperatures ca. >10 °C. Published 2022. This article is a U.S. Government work and is in the public domain in the USA.

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Section: Resultsmentioning

confidence: 99%

Ethyl formate dilution in carbon dioxide for fumigation control of the brown marmorated stink bug Halyomorpha halys, Stål (Hemiptera: Pentatomidae)

Kawagoe

Abrams

Lourie

et al. 2022

Pest Management Science

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“…a = 100 × n r . Mortality was also expressed as a function of the number of specimens treated via probit analysis of Finney (1944) at the 95% confidence level (CL), as further derived in Couey and Chew (1986). All specimens, treated as well as nontreated controls, were frozen and archived at SJVASC, with a subset dissected for confirmation of diapause.…”

Section: Methodsmentioning

confidence: 99%

Confirmatory evaluation of eFUME for control of brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae)

Corbett

Cullum

Abrams

et al. 2023

Journal of Economic Entomology

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The governments of Australia and New Zealand require a phytosanitary treatment to control adult brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), as overwintering aggregations have been intercepted in the importation pathway of various nonhorticultural consignments, including vehicles. The commercialized fumigant, eFUME, a 16.7% by mass dilution of ethyl formate in carbon dioxide, resulted in complete control of ca. 1,000 field-collected, naturally diapausing adult H. halys in each of 3 independent trials at 10 ± 0.5 °C (x¯ ± 2s) when ethyl formate levels in enclosure headspace were maintained steady-state at ca. 14.5 mg/liter for 4 h to yield Ct exposures ranging from 57.9 to 63.1 mg/liter h. Consistent with previous findings where greenhouse reared H. halys were controlled using laboratory formulations of this ethyl formate—carbon dioxide mixture, these confirmatory methods and results further inform technical and operational features of commercial practice.

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“…The lower bound estimate of mortality level ( Y ) at 95% CI for each replicate was derived from the formula: Y = 10log(0.05)/ x where x is the number of estimated treated individuals in the replicate. The formula was derived from Equation 3b in Couey and Chew (1986) for the case of zero survivors in a specified sample size.…”

Section: Methodsmentioning

confidence: 99%

Efficacy of an existing Ceratitis capitata (Diptera: Tephritidae) cold disinfestation treatment schedule for Ceratitis cosyra

Manrakhan

Daneel

Serfontein

et al. 2023

Journal of Economic Entomology

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The efficacy of an existing cold disinfestation postharvest treatment targeting Ceratitis capitata (Wiedemann) in citrus was determined for the marula fly, Ceratitis cosyra (Walker). The cold tolerances of C. capitata and C. cosyra were first quantified in artificial diet at 3.5 °C at different exposure periods for up to 18 days. Ceratitis capitata was found to be more cold tolerant than C. cosyra. At 3.5 °C, the duration to achieve 99.9968% mortality was calculated to be 11.57 days for C. capitata and 9.10 days for C. cosyra. Under an existing C. capitata cold treatment schedule at 1 °C for 14 days, the conditions required for complete mortality of the third larval stage of C. cosyra in orange, Citrus sinensis (L.) Osbeck cv. Valencia, were then determined. No survivors of C. cosyra in oranges were recorded beyond 11 days of cold treatment at 1 °C. The efficacy of this C. capitata treatment for disinfestation of C. cosyra was thereafter confirmed in large scale trials in Valencia oranges. In the large-scale trial at the lowest mean temperature of 1.19 °C for 14 days, there were no survivors from a total of 85 490 treated C. cosyra third instars in oranges. Since C. capitata was shown to be more cold tolerant than C. cosyra and a large scale test demonstrated at least 99.9965% efficacy after 14 days at 1.19 °C, compared with the established effective C. capitata cold treatment of 14 days at 1.11 °C, cold disinfestation treatments for C. capitata should be at least equally effective against C. cosyra.

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Confidence Limits and Sample Size in Quarantine Research

Cited by 143 publications

References 0 publications

Ethyl formate dilution in carbon dioxide for fumigation control of the brown marmorated stink bug Halyomorpha halys, Stål (Hemiptera: Pentatomidae)

Ethyl formate dilution in carbon dioxide for fumigation control of the brown marmorated stink bug Halyomorpha halys, Stål (Hemiptera: Pentatomidae)

Confirmatory evaluation of eFUME for control of brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae)

Efficacy of an existing Ceratitis capitata (Diptera: Tephritidae) cold disinfestation treatment schedule for Ceratitis cosyra

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