Walter P. Gould

Hot Water Treatment and Insecticidal Coatings for Disinfesting Limes of Mealybugs (Homoptera: Pseudococcidae)

Abstract Hot water immersion and insecticidal coatings were tested to determine if they could be used to disinfest Persian limes, Citrus latifolia Tanaka, of the mealybug pests Planococcus citri Risso and Pseudococcus odermatti Miller & Williams. A 20-min 49°C hot water immersion treatment is effective in killing mealybugs and all other arthropods tested found externally on limes, or under the calyx. No insects or mites were found to survive after the 20-min hot water treatment. In this test, 7,200 limes were treated with 1,308 insects killed and zero survivors. Treatment at 49°C for 20 min did not significantly affect quality when treated fruit were compared with untreated control fruit. Four coatings were tested at a 3% rate: two petroleum-based oils (Ampol and Sunspray oil), a vegetable oil (natural oil), and a soap (Mpede). The coatings gave up to 94% kill (Ampol) of mealybugs, which is not sufficient to provide quarantine security. The coatings might be effective as a postharvest dip before shipment.

HOST STATUS OF MAMEY SAPOTE TO CARIBBEAN FRUIT FLY (DIPTERA: TEPHRITIDAE)

Field trapping of Anastrepha suspensa (Loew) in groves of mamey sapote, Pouteria sapota (Jacq.), showed that fly populations were present in high numbers in all of the groves used for the experiments. Fly populations were highest at the beginning and end of the sampling period. More than 646 fruit of mamey sapote weighing a total of 459.9 kg were exposed to Caribbean fruit flies either in the laboratory or under natural conditions. In one test in the laboratory, 9 Caribbean fruit fly larvae were recovered from mamey sapote fruit. All of the control guava fruit had infestations, some as high as 70 larvae per fruit. In the field tests, no mamey sapote had infestations of Caribbean fruit flies, either naturally occurring or from caged infestation tests. Pressure measurements showed that mamey sapotes averaged -80 to -130 Newtons which is much harder than guavas which averaged -30 Newtons. Magana and Pantin mamey sapote collected in the field in Florida were not found to be hosts to the Caribbean fruit fly, but laboratory infestation was found to occur.

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

Cold Torpor And Flight Threshold Of Anastrepha suspensa (Diptera: Tephritidae)

The Caribbean fruit fly, Anastrepha suspensa (Loew), is a pest of quarantine significance of many subtropical fruits in Florida. Fly free zones which require bait spraying with malathion when fly populations reach actionable levels, have been developed. Bait sprays also are used whenever new introductions of fruit fly species occur. Bait sprays will not be effective if the target population is immobile due to cold. The purpose of this study was to develop temperature thresholds for laboratory-reared and wild Anastrepha suspensa through controlled laboratory studies. This research determined that the cold torpor threshold for Caribbean fruit fly was 11.4C, and the flight threshold for 50% of the population was about 20C. It also was determined that the flight threshold of wild flies did not differ significantly from that of laboratory reared flies. Bait spray experiments and regular treatments could be scheduled to avoid cold periods when flies are not active.