Field Evaluation of a Binary Sex Pheromone for Sweetpotato Vine Borer (Lepidoptera: Crambidae) in Hawaii.

The sweetpotato vine borer, Omphisa anastomosalis (Guenée), is a primarily Asian pest of sweetpotato, Ipomoea batatas L. Damage by O. anastomosalis infestation can cause root yield losses of 30%-50%. A binary sex pheromone for O. anastomosalis, consisting of Type I [(10E,14E)-10,14-hexadecadienal (E10,E14-16:Ald)] and Type II [(3Z,6Z,9Z)-3,6,9-tricosatriene (Z3,Z6,Z9-23:H)] components, was identified in Vietnam from extracts of female pheromone glands. A structurally similar Type II compound [(3Z,6Z,9Z)-3,6,9-docosatriene (Z3,Z6,Z9-22:H)], not recovered from female pheromone glands, was also found to synergize the attractiveness of the Type I component. Additional field work has been needed to determine whether these synergistic enhancements of attractiveness also occur in other parts of the geographical distribution of this moth species. Herein, results of studies are reported which document that both Z3,Z6,Z9-23:H and Z3,Z6,Z9-22:H also synergistically enhance male response to E10,E14-16:Ald in Hawaii sweetpotato field populations. Trap catch tends to be enhanced with increase of dose and lower Type I:Type II ratios. Among the compound doses and ratios tested, trap catch increased with the addition of the Type II component by over 13 times relative to traps baited with the Type I component alone, which significantly enhanced sweetpotato vine borer detection. Using a 2.0 mg: 4.0 mg Type I: Type II loading, there was continued catch over 12 wk, during which time the Type I component weathered at a faster rate than the Type II component. This binary sex pheromone seems to have promise for both monitoring and suppression of field populations of O. anastomosalis throughout its geographical range.

Method for DNA Isolation From Sweetpotato Weevil (Coleoptera: Curculionidae) Collected in Pheromone-Baited Traps.

This study provides a protocol for the isolation of high-quality DNA from sweetpotato weevils (Cylas formicarius elegantulus (Summers)) collected from pheromone-baited aerial funnel traps. This study was based on our discovery that a 2-wk collection interval of sweetpotato weevils from pheromone traps did not permit isolation of intact high-quality genomic DNA. To test the effect of collection methods, i.e., sample collection interval and preservation method, on quality of isolated DNA, we placed freshly killed male sweetpotato weevils into aerial funnel traps in the field and removed subsamples at several times thereafter. DNA yield from freshly isolated (day = 0) samples was significantly greater than samples preserved in 70% ethanol or at -20°C, whereas there was no difference between 70% ethanol and -20°C storage. Likewise, DNA yield from freshly isolated (day = 0) samples was significantly greater than for later sampling times. Quality assessment of genomic DNA through gel electrophoresis and polymerase chain reaction (PCR) indicated isolation of high molecular weight DNA for all samples collected at t ≤ 7 d, but that DNA quality was degraded by 14 d. Our goal was to develop a reliable method for isolation of genomic DNA from field-collected sweetpotato weevil suitable for direct use in PCR. We discovered that it is critical to collect specimens from traps at an interval of 1 wk or less. Our findings allow for scheduling of sampling at reasonable intervals without the need for special materials. This has the added benefit of allowing individuals without special training to collect and prepare sweetpotato weevil specimens for genetic studies.

Field Trapping Bactrocera latifrons (Diptera: Tephritidae) with Select Eugenol Analogs That Have Been Found to Attract Other 'Non-Responsive' Fruit Fly Species.

Bactrocera latifrons (Hendel) (Diptera: Tephritidae) is a pest fruit fly species native to Oriental Asia which has invaded and established in Hawaii and Tanzania and has been recovered in detection trapping in California. It is largely non-responsive to the male lures cuelure and methyl eugenol. Alpha-ionol + cade oil is a moderately effective male B. latifrons attractant, but is not as attractive as cuelure or methyl eugenol are to other fruit fly species. An improved attractant is therefore desired. With the recent success in finding other non-responsive fruit fly species attracted to isoeugenol, methyl-isoeugenol, or dihydroeugenol in Australia and other countries, we wanted to assess whether B. latifrons might also respond to these “eugenol analogs.” Working with wild B. latifrons populations in Hawaii, we assessed the relative catch of B. latifrons in traps baited with the eugenol analogs with catch in traps baited with alpha-ionol, alpha-ionol + cade oil, or alpha-ionol + eugenol. Catch was significantly higher in traps baited with alpha-ionol + cade oil relative to traps with any of the other baits. There was, though, some male B. latifrons catch in traps baited with dihydroeugenol or isoeugenol but none in traps baited with methyl-isoeugenol.

Natural Field Infestation of Mangifera casturi and Mangifera lalijiwa by Oriental Fruit Fly, Bactrocera dorsalis (Diptera: Tephritidae).

Mango, Mangifera indica (Anacardiaceae), is a crop cultivated pantropically. There are, however, many other Mangifera spp ("mango relatives") which have much more restricted distributions and are poorly known but have potential to produce mango-like fruits in areas where mangoes do not grow well or could be tapped in mango breeding programs. Because of the restricted distribution of many of the Mangifera spp, there has also been limited data collected on susceptibility of their fruits to infestation by tephritid fruit flies which is important to know for concerns both for quality of production and for quarantine security of fruit exports. Here, we report on natural field infestation by the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae), of two mango relatives native to Indonesia: Mangifera casturi and Mangifera lalijiwa. Rates of infestation of fruits of these two Mangifera spp by tephritid fruit flies have not previously been reported.

Assessment of Navel Oranges, Clementine Tangerines, and Rutaceous Fruits as Hosts of Bactrocera cucurbitae and Bactrocera latifrons (Diptera: Tephritidae).

Export of Citrus spp. fruits may require risk mitigation measures if grown in areas with established tephritid fruit fly (Diptera: Tephritidae) populations capable of infesting the fruits. The host status of Citrus spp. fruits is unclear for two tephritid fruit fly species whose geographic ranges have expanded in recent years: melon fly, Bactrocera cucurbitae (Cocquillett), and Bactrocera latifrons (Hendel). In no choice cage infestation studies, B. latifrons oviposited into intact and punctured Washington navel oranges (Citrus sinensis [L.] Osbeck) and Clementine tangerines (C. reticulata L. var. Clementine), but eggs rarely developed to the adult stage. B. cucurbitae readily infested intact and punctured tangerines, and to a lesser extent punctured oranges, but did not infest intact oranges. Limited cage infestation and only a single literature report of field Citrus spp. infestation suggest that risk mitigation of Citrus spp. for B. latifrons is not needed. Risk mitigation options of Citrus spp. for B. cucurbitae, including heat and cold treatments and systems approaches, are discussed.

Melon Fly, Bactrocera cucurbitae (Diptera: Tephritidae), Infestation in Host Fruits in the Southwestern Islands of Japan Before the Initiation of Island-wide Population Suppression, as Recorded in Publications of Japanese Public Institutions.

Bactrocera cucurbitae (Coquillett) is a tephritid fruit fly native to the Indo-Malayan region. Its distribution, though, has extended to include Africa, temperate Asia, and a number of Pacific islands. It became established in Japan in 1919 in the Yaeyama Islands and spread north in the Southwestern Islands of Japan. It was subsequently eradicated from these islands by an eradication program that extended from 1972 to 1993. As part of an effort to develop a worldwide database on the status of fruits as hosts of melon fly, the infestation data gathered from host fruits collected in this eradication program, before the initiation of suppression activities, are summarized here. Bactrocera cucurbitae infestation was documented in 24 plant taxa of four plant families (Caricaceae, Cucurbitaceae, Moraceae, and Solanaceae), with the following four new hosts identified: Ficus erecta Thunb., F. pumila L. (Moraceae), Solanum erianthum D. Don (Solanaceae), and Zehneria liukiuensis Jeffrey ex Walker (Cucurbitaceae).

Green light synergistally enhances male sweetpotato weevil response to sex pheromone.

Sweetpotato, commercially grown in over 100 countries, is one of the ten most important staple crops in the world. Sweetpotato weevil is a major pest of sweetpotato in most areas of cultivation, the feeding of which induces production in the sweetpotato root of extremely bitter tasting and toxic sesquiterpenes which can render the sweetpotato unfit for consumption. A significant step towards improved management of this weevil species was the identification of a female-produced sex pheromone [(Z)-3-dodecenyl (E)-2-butenoate] to which males are highly attracted. Reported here are results of research that documents a nearly 5-fold increase in male sweetpotato weevil catch in traps baited with this pheromone and a green light provided by a solar-powered, light-emitting diode (LED). The combination of olfactory and night-visible visual cues significantly enhanced trap effectiveness for this nighttime-active insect species. These results provide promise for improved sweetpotato weevil detection and suppression in mass trapping programs.

Release and establishment of the parasitoid Diachasmimorpha kraussii against the tephritid fruit fly Bactrocera latifrons in Hawaii.

Diachasmimorpha kraussii (Fullaway) (Hymenoptera: Braconidae) was first released against Bactrocera latifrons (Hendel) (Diptera: Tephritidae) in Hawaii in March 2003. Over a three month period, eight releases, totaling 7,696 females and 3,968 males, were made in a turkeyberry, Solanum torvum Swartz (Solanales: Solanaceae) patch known to have a well established B. latifrons population. The establishment of D. kraussii was assessed through fruit collections conducted over a three-year period beyond the last release. D. kraussii was recovered 2 weeks, 31 months, and 39 months after the last parasitoid release, with collections not only from the release site, but also from a control site about 5.0 km distance from the release site. Recovery from fruit collections three years after the last parasitoid release confirmed that D. kraussii had become established in Hawaii. Parasitism rates were low, only 1.0-1.4%, compared to rates of 2.8-8.7% for the earlier established egg-larval parasitoid, Fopius arisanus (Sonan).

Distinguishing male and female Chinese rose beetles, Adoretus sinicus, with an overview of Adoretus species of biosecurity concern.

The Chinese rose beetle, Adoretus sinicus Burmeister (Coleoptera: Scarabaeidae: Rutelinae: Adoretini), is a broadly polyphagous scarab beetle that is economically important and causes damage to a wide variety of host plants including agricultural crops and ornamentals in Southeast Asia, China, the Hawaiian Islands and several other Pacific Islands. The species has become established in numerous regions and is of biosecurity concern because importation of this species to other regions poses a threat to agriculture due to its generalist herbivore feeding habits. Field and laboratory research directed towards control of the species is hampered by the lack of characteristics that allow accurate determination of the sexes on live beetles in the field. Here, three recognizable and reliable non-destructive morphological differences between the sexes of A. sinicus are documented: (1) the form of the terminal sternite; (2) the length to width ratio of protarsomere 1, and; 3) the ratio of the combined length of protarsomeres 2-4 to the length of protarsomere 1. Because many Adoretus species are of biosecurity concern, and because tools to identify Adoretus species are lacking, we review the natural history and research on control associated with A. sinicus as well as the genus as a whole.

Assessment of attractiveness of cassava as a roosting plant for the melon fly, Bactrocera cucurbitae, and the Oriental fruit fly, B. dorsalis.

Application of bait spray to crop borders is a standard approach for suppression of melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) populations and may also be of value for suppression of oriental fruit fly, B. dorsalis (Hendel) populations. Establishment of preferred roosting hosts as crop borders may help to improve suppression of both fruit fly species by providing sites for bait spray applications. In an area-wide B. cucurbitae suppression trial, the question was raised as to whether cassava, Manihot esculenta Crantz (Euphorbiales: Euphorbiaceae), could be used as a B. cucurbitae roosting host. M. esculenta was of interest as a roosting host because, in contrast to many other identified preferred roosting hosts, it would also be a crop potentially increasing the productivity of the crop production system overall. As a short-lived and shrubby perennial, M. esculenta potentially constitutes a crop with more persistent roosting foliage than an annual crop such as corn, Zea mays L. (Cyperales: Poaceae), that has often been planted as a roosting host for B. cucurbitae control. Using protein-baited traps set amidst potted plants placed adjacent to a papaya Carica papaya L. (Violales: Caricaceae) orchard known to have established populations of B. cucurbitae and B. dorsalis, the effectiveness of M. esculenta as a roosting host was assessed by comparing its attractiveness to that of castor bean, Ricinus communis L (Malpighiales: Euphorbiaceae), previously identified as one of the most attractive roosting hosts for B. cucurbitae, and to corn, a crop which has been planted as a roosting host for help in B. cucurbitae control. The results showed that use of M. esculenta as a roosting host is comparable to use of R. communis by both B. cucurbitae and B. dorsalis. These results provide encouragement to incorporate M. esculenta on a farm as a trap crop (i.e. site for bait spray application). This has the advantage of having the trap crop be a crop on its own (as opposed to castor bean) and, among prospective crops that could be used as a trap crop, has foliage more persistent than an annual trap crop such as corn.

Evaluation of readmission ink as a marker for dispersal studies with the oriental fruit fly, Bactrocera dorsalis.

In this text we present a new marking dye, readmission ink, Blak-Ray, for the purpose of insect movement studies. The dye was tested in a controlled experiment with Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) in anticipation of a long distance movement study planned for the following year with the same species. 700 individuals of both sexes were marked with the dye and placed in holding containers. Both the percentage of mortality and the ease of dye detection were monitored throughout a five-week period. Results showed minimal fly mortality and exceptional ease of dye detection.

Area-wide suppression of the Mediterranean fruit fly, Ceratitis capitata, and the Oriental fruit fly, Bactrocera dorsalis, in Kamuela, Hawaii.

The United States Department of Agriculture's Agricultural Research Service initiated an area-wide fruit fly management program in Hawaii in 2000. The first demonstration site was established in Kamuela, Hawaii, USA. This paper documents suppression of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in a 40 km2 area containing urban, rural and agricultural zones during a 6 year period. The suppression techniques included sanitation, GF-120 NF Naturalyte Fruit Fly Bait sprays, male annihilation, Biolure traps, and parasitoids against C. capitata and B. dorsalis. In addition, small numbers of sterile males were released against B. dorsalis. Substantial reductions in fruit infestation levels were achieved for both species (90.7 and 60.7% for C. capitata and B. dorsalis, respectively) throughout the treatment period. Fruit fly captures in the 40 km2 treatment area were significantly lower during the 6 year period than those recorded in three non-treated areas. The strategy of combining suppression techniques in an area-wide approach is discussed.

Ring-fluorinated analog of methyl eugenol: attractiveness to and metabolism in the oriental fruit fly, Bactrocera dorsalis (Hendel).

Oriental fruit fly, Bactrocera dorsalis (Hendel), males are highly attracted to the natural phenylpropanoid methyl eugenol (ME). They compulsively feed on ME and metabolize it to ring and side-chain hydroxylated compounds that have both pheromonal and allomonal functions. Side-chain metabolic activation of ME leading to (E)-coniferyl alcohol has long been recognized as a primary reason for hepatocarcinogenicity of this compound in rodents. Earlier, we demonstrated that introduction of a fluorine atom at the terminal carbon of the ME side chain significantly depressed metabolism and specifically reduced formation of coniferyl alcohol but had little effect on field attractiveness to B. dorsalis. In the current paper, we demonstrate that fluorination of ME at the 4 position of the aromatic ring blocks metabolic ring-hydroxylation but overall enhances side-chain metabolism by increasing production of fluorinated (E)-coniferyl alcohol. In laboratory experiments, oriental fruit fly males were attracted to and readily consumed 1,2-dimethoxy-4-fluoro-5-(2-propenyl)benzene (I) at rates similar to ME but metabolized it faster. Flies that consumed the fluorine analog were as healthy post feeding as ones fed on methyl eugenol. In field trials, the fluorine analog I was approximately 50% less attractive to male B. dorsalis than ME.

Assessment of attractiveness of plants as roosting sites for the melon fly, Bactrocera cucurbitae, and oriental fruit fly, Bactrocera dorsalis.

The use of toxic protein bait sprays to suppress melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), populations typically involves application to vegetation bordering agricultural host areas where the adults seek shelter ("roost"). Although bait spray applications for suppression of oriental fruit fly, Bactrocera dorsalis (Hendel), populations have traditionally been applied to the host crop, rather than to crop borders, roosting by oriental fruit flies in borders of some crop species, such as papaya, Carica papaya L. (Brassicales: Caricaceae), suggests that bait spray applications to crop borders could also help in suppression of B. dorsalis populations. In order to develop improved recommendations for application of bait sprays to border plants for suppression of melon fly and oriental fruit fly populations, the relative attractiveness of a range of plant species, in a vegetative (non-flowering) stage, was tested to wild melon fly and oriental fruit fly populations established in a papaya orchard in Hawaii. A total of 20 plant species were evaluated, divided into four categories: 1) border plants, including corn, Zea mays L. (Poales: Poaceae), windbreaks and broad-leaved ornamentals, 7 species; 2) weed plants commonly found in agricultural fields in Hawaii, 6 species; 3) host crop plants, 1 species- zucchini, Cucurbita pepo L. (Violales: Curcurbitaceae), and 4) locally grown fruit trees, 6 species. Plants were established in pots and placed in an open field, in clusters encircling protein bait traps, 20 m away from the papaya orchard. Castor bean, Ricinus communis L. (Euphorbiales: Euphorbiaceae), panax, Polyscias guilfoylei (Bull) Bailey (Apiales: Araliaceae), tiger's claw, Erythnna variegata L. (Fabales: Fabaceae), and guava, Psidium guajava L. (Myrtales: Myrtaceae) were identified as preferred roosting hosts for the melon fly, and tiger's claw, panax, castor bean, Canada cocklebur, Xanthium strumarium L. (Asterales: Asteraceae), Brazilian pepper tree, Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae), ti plant, Cordyline terminate (L.) Chev.(Liliales: Liliaceae), guava and several Citrus spp. were identified as preferred roosting hosts for oriental fruit fly. Guava had not previously been identified as a preferred roosting host for melon fly. Other than for the use of panax as a roosting host, there has previously been little attention to roosting hosts for oriental fruit fly. Establishment of preferred roosting hosts as crop borders may help to improve suppression of both fruit fly species by providing sites for bait spray applications. Further research is needed to assess the use of vegetation bordering other host crops as roosting hosts, especially for oriental fruit fly.

Movement of sterile male Bactrocera cucurbitae (Diptera: Tephritidae) in a Hawaiian agroecosystem.

The melon fly, Bactrocera cucurbitae Coquillett, invaded the Hawaiian Island chain in 1895. In 1999, a program sponsored by the USDA-ARS to control melon fly and other tephritid pests in Hawaii over a wide area was initiated on the islands of Hawaii, Maui, and Oahu. To control these flies in an areawide setting, understanding how flies move within the landscape is important. To explore the movement of this fly, we examined the movement of marked, male, sterile, laboratory-reared B. cucurbitae on the island of Hawaii in an agricultural setting. Two releases of dyed, sterile flies consisting of approximately 15,000 flies, were released 6 wk apart. Released flies were trapped back by using Moroccan traps baited with a male attractant. These two releases suggest that in the Hawaiian agricultural areas where the areawide control is being sought, melon flies do not move extensively when there are abundant larval host and adult roosting sites. Over the course of this study, only one fly made it the maximum distance that we could detect fly movement (approximately 2,000 m in 2 wk). From these data, it seems that the flies dispersed throughout the study area but then moved very little thereafter. This is very apparent in the second release where the recovery rate after the second week was still fairly high, suggesting that if there are plenty of host fields and roosting sites the flies are unlikely to move.

Comparative evaluation of spinosad and phloxine B as toxicants in protein baits for suppression of three fruit fly (Diptera: Tephritidae) species.

Spinosad and phloxine B are two more environmentally friendly alternative toxicants to malathion for use in bait sprays for tephritid fruit fly suppression or eradication programs. Laboratory tests were conducted to assess the relative toxicity of these two toxicants for melon fly, Bactrocera cucurbitae Coquillett; oriental fruit fly, Bactrocera dorsalis Hendel; and Mediterranean fruit fly, Ceratitis capitata (Wiedemann) females. Field tests also were conducted with all three species to compare these toxicants outdoors under higher light and temperature conditions. In laboratory tests, spinosad was effective at much lower concentrations with LC50 values at 5 h of 9.16, 9.03, and 4.30 compared with 250.0, 562.1, and 658.9 for phloxine B (27, 62, and 153 times higher) for these three species, respectively. At 16 ppm spinosad, LT50 values were lower for all three species (significantly lower for C. capitata and B. dorsalis) than 630 ppm phloxine B LT50 values. At 6.3 ppm spinosad, the LT50 value for C. capitata (3.94) was still significantly less than the 630 ppm phloxine B LT50 value (6.33). For all species, the 100 ppm spinosad concentrations gave LT50 values of < 2 h. In comparison among species, C. capitata was significantly more sensitive to spinosad than were B. cucurbitae or B. dorsalis, whereas B. cucurbitae was significantly more sensitive to phloxine B than were C. capitata or B. dorsalis. LC50 values were reduced for both toxicants in outdoor tests, with greater reductions for phloxine B than for spinosad for B. dorsalis and B. cucurbitae. Fly behavior, though, is likely to keep flies from being exposed to maximum possible outdoor light intensities. Comparable levels of population suppression for any of the three species tested here will require a much higher concentration of phloxine B than spinosad in the bait.

Active ingredients in cade oil that synergize attractiveness of alpha-ionol to male Bactrocera latifrons (Diptera: Tephritidae).

Cade oil, a commercially available essential oil produced by destructive distillation of juniper, Juniperus oxycedrus L., twigs, is known to synergize the attractancy of alpha-ionol to male Bactrocera latifrons (Hendel). Through chemical fractionation and outdoor olfactometer-based bioassays, seven compounds in cade oil were identified that potentially could provide some level of synergism. Tests with sterile laboratory flies showed that four of the seven compounds (eugenol, isoeugenol, 2-methoxy-4-ethylphenol, and 2-methoxy-4-propylphenol), together with a closely related compound not found in cade oil, 2-methoxy-4-methylphenol, are capable of synergizing the attractiveness of alpha-ionol to male B. latifrons under field conditions. The similarity in structures of these five synergistic compounds shows that there is a response to a core 2-methoxyphenol structure, with fly response little affected by some variation in the composition of the side chain on the number 4 carbon. Because identified synergists were structurally similar, only one compound, eugenol, was selected for further field studies. In an 8-wk weathering test, using released sterile flies, traps baited with alpha-ionol + eugenol had catches comparable with catches at traps baited with alpha-ionol + cade oil, with catches generally increased with a higher eugenol loading. For both eugenol and cade oil, catches tended to be better when these synergists were deployed on separate wicks from the alpha-ionol. Eugenol and alpha-ionol, however, were unable to provide attraction comparable with that of cade oil and alpha-ionol in tests with wild fly populations.

Efficacy and residues of phloxine B and uranine for the suppression of Mediterranean fruit fly in coffee fields.

The field efficacy of a bait containing phloxine B, uranine and Provesta 621 protein was tested against Mediterranean fruit fly (Ceratitis capitata; Medfly) by aerial and ground spraying in about 84 ha of coffee fields in Kauai, Hawaii, USA. Concurrently, soil and crop samples were collected from the aerially sprayed field and its unsprayed control field for residue studies. Efficacy of the sprays was assessed through trapping with both protein-baited and trimedlure-baited traps and through the infestation level of coffee cherries collected at least three-quarters ripe. The C capitata population was low at the start of the aerial and ground spray studies, but dramatically increased in the control fields. This increase coincided with initial ripening of coffee cherries. During times of peak population levels, C capitata populations were reduced by more than 91% in the ground-sprayed field and 99% in the aerial-sprayed field, relative to the populations in their respective control fields and based on protein-baited trap catches. Results of residue analyses indicated that uranine dissipated quickly compared with phloxine B on coffee and soil. Coffee samples collected at pre-spray periods had phloxine B residues of 7.2-25.5 ng g-1 on berries. Phloxine B concentrations were much higher on coffee leaves (163-1120 ng g-1). Lower concentrations of the dye were found from coffee samples collected during rainy days. Average phloxine B concentrations immediately after spraying were 56 and 2840 ng g-1 in coffee berries and leaves, respectively. Dissipation of phloxine B on berries was fast, with a half-life (t1/2) of 3 days. Dissipation of phloxine B on leaves was fitted to two linear phases: the initial (0-4 days) with a shorter t1/2 of 3 days and the later phase (4-28 days) with a longer t1/2 of 15 days. Average concentrations of phloxine B in the top soil ranged from 50 to 590 ng g-1 at pre-spray. Phloxine B initial concentration (770 ng g-1) reached a plateau immediately after the last spraying, but showed a steady decline over time with t1/2 of 16 days. Fast dissipation of the dyes in the field indicates that these chemicals may be environmentally compatible and therefore a promising alternative for fruit fly control.