Michael K. Hennessey

SPINOSAD BAIT FOR THE CARIBBEAN FRUIT FLY (DIPTERA: TEPHRITIDAE)

The establishment of the Caribbean fruit fly, Anastrepha suspensa (Loew), in Florida resulted in the need for quarantine treatments of citrus for shipment to certain states and countries. The state of Florida has established a fly-free protocol that permits shipment from areas in compliance without further treatment. One option of the protocol calls for the use of a toxic bait cover spray; however, sprays containing malathion are required to contain 190,000 ppm active ingredient. Thus, alternative pesticides are needed because of environmental, human health, and property damage concerns with malathion. Spinosad, an extract of a bacterial broth, is a contact and stomach poison for target pests. It was combined with a sugar-yeast hydrolysate mixture and tested as a bait spray on colony-reared adult flies in a no-choice test. The EC 99 values were estimated to be 9.4 and 5.8 ppm for sexually mature females and males, respectively. These relatively low values indicate that spinosad is an excellent candidate for field testing.

Confidence Limits and Sample Size for Determining Nonhost Status of Fruits and Vegetables to Tephritid Fruit Flies as a Quarantine Measure

Abstract Quarantine measures including treatments are applied to exported fruit and vegetable commodities to control regulatory fruit fly pests and to reduce the likelihood of their introduction into new areas. Nonhost status can be an effective measure used to achieve quarantine security. As with quarantine treatments, nonhost status can stand alone as a measure if there is high efficacy and statistical confidence. The numbers of insects or fruit tested during investigation of nonhost status will determine the level of statistical confidence. If the level of confidence of nonhost status is not high, then additional measures may be required to achieve quarantine security as part of a systems approach. Certain countries require that either 99.99 or 99.9968% mortality, as a measure of efficacy, at the 95% confidence level, be achieved by a quarantine treatment to meet quarantine security. This article outlines how the level of confidence in nonhost status can be quantified so that its equivalency to traditional quarantine treatments may be demonstrated. Incorporating sample size and confidence levels into host status testing protocols along with efficacy will lead to greater consistency by regulatory decision-makers in interpreting results and, therefore, to more technically sound decisions on host status.

Residential Composting of Infested Fruit: A Potential Pathway for Spread of Anastrepha Fruit Flies (Diptera: Tephritidae)

Abstract Composting plant waste is a beneficial practice commonly used by American gardeners, but disposal of infested fruit directly into the environment creates a potential pathway for introduction of insect pests. This study estimates the likelihood of adult emergence for exotic fruit flies (Tephritidae) from residential composting in south Florida. Ripe grapefruits, Citrus × paradisi Macfad., were infested with the Caribbean fruit fly, Anastrepha suspensa (Loew). Half of the infested fruit was placed onto outdoor compost piles and half was maintained under controlled laboratory conditions. Adult fly emergence was recorded daily for 30 d from both the compost piles and control bins. Compost temperature, air temperature, relative humidity, and precipitation were monitored, and the study was repeated 4 times under different seasonal conditions. Despite high mortality of flies from the composted fruit relative to control fruit, the overall risk of a potentially mated female emerging from composted fruit was calculated to be ∼10%. Of the environmental factors evaluated, compost temperature was found to have a significant effect on adult emergence. Mortality approached 100% in piles with maximum compost temperatures ≥48°C. This report provides experimental data in support of quantitative risk analysis for a tephritid-compost pathway.

MORTALITY OF ANASTREPHA SUSPENSA (DIPTERA: TEPHRITIDAE) IN CARAMBOLAS TREATED WITH COLD WATER PRECOOLING AND COLD STORAGE

The Caribbean fruit fly, Anastrepha suspensa (Loew), is a pest of quarantine significance of carambolas. The fruits are subjected to cold storage quarantine treatment when shipped to areas outside of the known range and where the fly could survive. In this study, rapid cooling in cold water increased mortality of Caribbean fruit fly larvae in carambolas over passive air cooling. Air-cooled carambolas required more than 24 h to cool to the treatment temperature of 1.1°C, while water-cooled fruits required only about 45 min. After 1 day, Anastrepha suspensa larvae had greater than 65% mortality in water-cooled carambolas, while mortality of larvae in air-cooled fruits was only 20%. Mortality of larvae in water-cooled fruits was 98% at 4 days, and 100% (1,900 larvae treated) after 9 days. Twenty six larvae were recovered from air-cooled fruits after 4 days (1,900 larvae treated), and one larva after 11 days of treatment. Larval mortality from cold-water-treated fruit reached probit 9 in 8 days, about 2/3 the time (13 days) required for the same level of mortality of larvae in air-cooled fruits. This difference in mortality is probably due to the rapidity of the cooling. It may be possible to use this modification to shorten the current cold treatment of 12 days at 1.1°C for Florida carambolas.

Anastrepha edentata and Other Fruit Flies (Diptera: Tephritidae) Detected on Key Largo, Florida

Several Anastrepha species (Diptera: Tephritidae) are quarantine pests of commercial fruits in the New World. Florida is home to one such pest, the introduced Anastrepha suspensa (Loew) (Caribbean fruit fly), plus three other Anastrepha species that are not considered of economic importance (Foote et al. 1993; Sutton & Steck 2005). One of these latter species, Anastrepha edentata Stone, is particularly mysterious, as no host has ever been reported from anywhere in its known range of South Florida and Puerto Rico (Norrbom 2004). We attempted to document its phenology and discover its host(s) through bait trapping and rearing from fruit collections in Dagny Johnson Key Largo Hammock Botanical State Park, Key Largo, Florida, during 1994-1996. Some fruit samples were also taken from Long Key State Park, Long Key, Florida, during the same period and during earlier periods. Both areas are subtropical West Indian hardwood forests. Ten to 16 plastic McPhail traps baited with torula yeast/borax tablets dissolved in water were suspended on the branches of small trees. Traps were hung 2 m off the ground, placed at 50-100-m intervals along a narrow, unpaved trail in the park, and were checked weekly from 25 Feb 1994 to 23 Feb 1996. In total, 21 A. edentata adults were trapped on 10 different occasions (Table 1). This is the first substantial collection of the species since 1934-1937, when the fly was first discovered and trapped in relatively large numbers during an intensive fruit fly survey in South Florida (Brown 1937; Clark et al. 1996). The fly has been captured on only a handful of other occasions (see Norrbom 2007 and records of the Florida Department of Agriculture, Division of Plant Industry (FDACS/ DPI) and Florida State Collection of Arthropods (FSCA)), despite extensive, routine fruit fly trapping in nearby suburban Key Largo plus other Florida Keys and large areas of Monroe