Lori A. Carvalho

Attraction of female mediterranean fruit flies to the five major components of male-produced pheromone in a laboratory flight tunnel.

Attraction and pheromonal activity of five major identified components of the male-produced sex pheromone of the Mediterranean fruit flyCeratitis capitata to virgin laboratory-reared females was assessed in a laboratory flight tunnel. Dual-choice competitive assays were run to establish a baseline response of virgin females to live male pheromone, individual components, and an ensemble of all five compounds alone (air control) and competitively against one another. Approximately 50% of the females released in the tunnel were captured on leaf models emitting pheromonal odors from five live males. Over 37% of released females responded to an ensemble of five major identified components presented in individual capillaries. Response of females to individual components was less than 10%. Competitive assays showed the live male-produced pheromone to be more attractive than either the five major component ensemble (FMCE) or individual components. Further research is likely to identify other male-produced compounds with pheromonal activity that could improve development of a pheromone-based trap for monitoring Mediterranean fruit fly populations.

Behavioural switch of female Mediterranean fruit fly, Ceratitis capitata: mating and oviposition activity in outdoor field cages in Hawaii

1 Laboratory‐reared normal, and wild female Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were assayed in outdoor field cages to assess the impact of a mating‐induced behavioural switch on mating and subsequent oviposition activity.

Evaluation of lure dispensers for fruit fly surveillance in New Zealand

BACKGROUND Fruit flies (Diptera: Tephritidae) represent a major biosecurity threat to the horticulture sector of New Zealand, which is entirely free of these invasive pests. A nationwide surveillance programme is conducted to ensure any incursion is detected as early as possible. A review of the lure dispensers used is reported here. RESULTS Lure dispenser emission trials found that the currently used lure plugs release lure more slowly under New Zealand subtropical to temperate climates than wafer dispensers. Subsequent trapping experiments at high altitude in Hawaii (as a mimic of New Zealand meteorological and expected fruit fly ecological conditions) compared Lynfield traps baited with the existing lure plug dispensers and newer wafer dispensers. Catches of wild Oriental fruit flies, Bactrocera dorsalis (Hendel), were 9.5-fold higher with methyl eugenol wafers than with the plugs. Recaptures of sterile melon flies, Bactrocera cucurbitae (Coquillet), were 2.6-fold higher with cuelure wafers than with the plugs. Recaptures of sterile Mediterranean fruit flies, Ceratitis capitata Weid., were not significantly higher with trimedlure wafers than with the plugs. CONCLUSIONS Release rate and trapping experiments found new lure dispensers differed in release rate characteristics from existing dispensers under temperate and subtropical conditions, and indicated some potential for improvement in surveillance efficacy.

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 ∼50% less attractive to male B. dorsalis than ME.

Field Attraction of Mediterranean Fruit Fly, Ceratitis capitata (Wiedemann) to Synthetic Stereoselective Enantiomers of the Ceralure B1 Isomer

Stereoselectively synthesized enantiomers of ethyl cis-5-iodotrans-2-methylcyclohexane-1-carboxylate (ceralure B1), a potent lure for male Mediterranean fruit flies, were tested in the laboratory and the field against laboratory reared sterile flies. The (−)-ceralure B1 enantiomer was significantly more attractive than the (+)-ceralure B1 antipode. Dose–response studies of the above compounds demonstrated that (−)-ceralure B1 and to a lesser extent, racemic ceralure B1, captured consistently more male flies than trimedlure, the current male attractant used in detection programs. Longevity tests demonstrated that, over a three-week period, both (−)-ceralure B1 and racemic ceralure B1 caught significantly more flies than trimedlure. The synthesis of specific enantiomers of ceralure B1 shows great promise as a male attractant that could replace trimedlure for detection and delimitation in action programs aimed at this exotic pest.

Field Response of Mediterranean Fruit Fly (Diptera: Tephritidae) to Ceralure B1: Evaluations of enantiomeric B1 Ratios on Fly Captures

Abstract (−)-Ceralure B1 (ethyl-cis-5-iodo-trans-2-methylcyclohexane-1-carboxylate), a male attractant for the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is significantly more attractive than trimedlure (tert-butyl esters of 4(5)-chloro-2-methylcyclohexane-1-carboxylate), the current standard male attractant used in detection programs. This article reports studies that compare the effectiveness of racemic ceralure B1, mixtures of racemic ceralure B1 and pure (−)-ceralure B1, and trimedlure in field tests conducted in Hawaii, Africa, and Spain with wild Mediterranean fruit flies and in Florida with sterile released Mediterranean fruit fly. Trapping results showed that doses of (−)-ceralure B1 of 87.5 and 75% are just as effective as the 98% (−)-ceralure B1 and the racemic form to be almost as attractive. In nearly all studies, the racemic ceralure B1 was significantly better than trimedlure. These studies suggest that the racemic ceralure B1 could be a viable replacement for trimedlure in areawide detection programs for Mediterranean fruit fly. Synthesizing racemic ceralure B1 instead of a specific stereoselective enantiomer of ceralure B1 would likely be more cost-effective to produce and also might be useful in control as well as detection of this pest.

Effect of heat shock and quarantine cold treatment with a warm temperature spike on survival of Mediterranean fruit fly eggs and fruit quality in Hawaii-grown 'Sharwil' avocado

The effects of a transient (warming) temperature spike on efficacy of an APHIS approved quarantine cold treatment, T107 (a), against Mediterranean fruit fly, Ceratitis capitata, was tested on Hawaii grown ‘Sharwil’ avocados. Avocados infested with late stage eggs were subjected to a warming temperature spike (ca. 4.2°C for 1 h) at 6–9 days into the treatment and subsequently allowed to resume the treatment until conclusion (12 days at <1.1°C, 14 days at <1.67°C or 16 days at <2.2°C). Insertion of a ca. 4.2°C temperature spike into the treatment at 6–9 days had no effect on the efficacy of the quarantine cold treatment when fruit were allowed to resume the treatment to completion. Infested fruit which did not receive a ‘heat shock’ treatment (recommended to improve fruit quality) and subjected to cold treatment for 6–16 days at either <1.1, <1.67 or <2.2°C (fruit center temperature) had no survivors in the fruit by the 9th day of cold treatment. Infested avocados subjected to a ‘heat shock’ treatment for 10–12 h at 38°C prior to cold treatment (as above) had no survivors in the fruit by the 8th day of cold treatment. Results of this study indicate that a transient (warm) temperature spike of ca. 4.2°C of the type experienced during an in-transit cold treatment of Hawaii grown ‘Sharwil’ avocados will not compromise the efficacy of the treatment. This study also reconfirmed that the T107 (a) cold treatment (as stated in the APHIS treatment manual) is efficacious against Mediterranean fruit fly eggs in ‘Sharwil’ avocados, and that use of a ‘heat shock’ to prevent chilling injury during the cold treatment did not extend survivorship of fruit fly eggs. Studies on the effects of prolonged (18–28 day) cold storage on fruit quality indicated that avocados can be stored at quarantine cold temperature (pulp, 1.1–2.2°C) for up to 24 days without significant loss of external and internal quality compared to fruit quality at 12–16 days storage. Also, shelf life, Gray Flesh discoloration (of internal tissue), and disease were not affected by the prolonged storage duration.

Performance of methyl eugenol + matrix + toxicant combinations under field conditions in Hawaii and California for trapping Bactrocera dorsalis (Diptera: Tephritidae).

ABSTRACT The oriental fruit fly, Bactrocera dorsalis (Hendel) is a major pest of many fruit crops worldwide. Current detection programs by federal and state agencies in the United States use a grid of traps consisting of liquid methyl eugenol (lure) and naled (toxicant) applied to cotton wicks and hung inside the trap. In recent years efforts have been made to incorporate these chemicals into various solid-type matrices that could be individually packaged to reduce human exposure to the chemicals and improve handling. New solid formulations containing methyl eugenol and either naled or dichlorovinyl dimethyl phosphate toxicants were compared with the standard formulations on cotton wicks in large scale field evaluation in Hawaii. Two reduced risk toxicants (spinosad and Rynaxypyr) were also evaluated. In one test the solid lure-toxicant-matrix combinations were sent to California to be weathered under California climate conditions and then sent back to Hawaii for evaluation. The polymer matrices with lure and toxicant were found to be as attractive as baited wicks and have the same longevity of attraction regardless of being weathered in Hawaii or in California. The new ingestible toxicants were also effective, although further testing of these ingestible lure + toxicant + matrix products is necessary.

Cucumber Lure Trapping of Zeugodacus cucurbitae (Diptera: Tephritidae) in Hawaii and Taiwan: Longevity and Nontargets Captures

Abstract The melon fly, Zeugodacus cucurbitae (Coquillett), is a serious pest of tropical horticulture, causing damage to cucurbits, tree fruits, and fruiting vegetables. Melon flies are especially attractive to freshly sliced cucumber, and this has led to the identification of a nine-compound kairomone lure that can be used to trap both female and male flies. In this study, a seven-compound lure, containing (Z)-6-nonenal, (Z)-6-nonen-1-ol, 1-octen-3-ol, (E,Z)-2,6nonadienal, (E)-2-nonenal, hexanal, and 1-hexanol, was formulated into PVC plugs (100 or 300 mg/plug) for field testing in wet traps. In Hawaii, 100 mg of the seven-compound cucumber lure, loaded in either plugs or glass capillaries, attracted more flies than traps containing Solulys protein over a 9-wk period. However, both cucumber lure formulations showed marked declines in the number of flies trapped after 3 wk. Similar results were obtained during a 6-wk field trial using 100 mg cucumber lure plugs in Taiwan. Increasing the cucumber lure loading rate to 300 mg/lure increased the effective trapping life of the attractant during a second 9-wk field trial conducted in Hawaii. The synthetic cucumber lure showed female-biased sex ratios in trap captures in the Taiwanese and second Hawaiian field trials. Protein lures captures were female-biased in all three field trials. Wet traps in Hawaii containing the cucumber lure were found to capture 25–30 nontarget insects/trap/week, less than half that captured with Solulys. Captured nontarget insects represented 37 families in 10 orders. The most common families caught were Ceratopogonidae (∼9 flies/trap) and Gryllidae (∼7 crickets/trap).

Disruption of Darna pallivitta (Lepidoptera: Limacodidae) by Conventional and Mobile Pheromone Deployment

Identification of the Darna pallivitta (Moore) pheromone component n-butyl (E)-7,9-decadienoate (E7,9-10:COOn-Bu) has made it possible to investigate communication disruption to control this lepidopteran pest. Conventional communication disruption trials showed marked decreases in the mean number of male moths captured in E7,9-10:COOnBu-treated fields compared with control fields. For traps baited with E7,9-10:COOnBu, percent disruptions were 94.4% and 92.1% for septa (1 g pheromone/ha, 1-wk trial duration) and spirals (6 g pheromone/ha, 8-wk trial duration) respectively. For traps baited with virgin female moths, percent disruption was 73.3% using septa disruptors (1 g pheromone/ha, 1-wk trial duration). Mobile communication disruption using Bactrocera cucurbitae (Coquillett) as carriers for E7,9-10:COOn-Bu was evaluated in the following three areas: fly survivorship, attraction of male moths to treated flies, and moth disruption in a small-scale field trial. Topical application of E7,9-10:COOnBu showed no significant decrease in survivorship at 50 and 80 µg/fly. However, decreased survivorship was observed at 100 µg/fly and linear regression showed E7,9-10:COOnBu dose was significantly correlated with B. cucurbitae survivorship. Traps containing honey–pheromone-fed flies attracted and caught D. pallivitta over a 1-wk period, demonstrating the attractiveness of the carrier. Releasing E7,9-10:COOnBu-fed B. cucurbitae (∼2 g pheromone/ha, 1-wk trial duration) resulted in significantly reduced trap catches in treatment fields compared with control fields on the first 2 d of the field trial. Percent disruptions were 84.7% (day 1) and 56.0% (day 2). These results suggest that both conventional communication disruption and mobile communication disruption have potential to control D. pallivitta.