Efficacy of two synthetic food-odor lures for Mexican fruit flies (Diptera: Tephritidae) is determined by trap type

Sterile mass-reared Mexican fruit flies, Anastrepha ludens (Loew), were trapped in a citrus orchard by using multilure traps and cylindrical sticky traps baited with Advanced Pheromone Technologies Anastrepha fruit fly (AFF) lures or Suterra BioLure two-component (ammonium acetate and putrescine) MFF lures (BioLures). The cylinder trap/AFF lure combination was the best trap over the first 6 wk, the multilure trap/BioLure combination was best during weeks 6-12, and the multilure trap/AFF lure combination was best during the last 6 wk. The multilure trap/BioLure combination was best overall by 36% over the cylinder trap/AFF lure combination, and 57% over the multilure trap/AFF lure combination. Cylinder traps with BioLures were the least effective trap/lure combination throughout the experiment, capturing only half as many flies as cylinder traps with AFF lures. Captures with cylinder traps baited with either lure and multilure traps with BioLures were female biased. For the most part, both lures remained highly attractive and emitted detectable amounts of attractive components under hot field conditions for the duration of the 18-wk experiment. Total emission of ammonia was 4 times greater and 1-pyrroline at least 10 times greater from AFF lures compared with BioLures. Correlations of trap and lure performance with ammonia emission and weather were determined, but no conclusions were possible. Results indicate that BioLures would be the lure of choice in multilure or other McPhail-type traps and AFF lures would be superior with most sticky traps or kill stations that attract flies to outer (not enclosed) surfaces.     

Attraction of the West Indian fruit fly to mango fruit volatiles

In this study, we investigated the attraction of West Indian fruit fly, Anastrepha obliqua (Macquart) (Diptera: Tephritidae), to volatiles of three mango [Mangifera indica L. (Anacardiaceae)] cultivars in field cage tests. The number of flies captured with Multilure traps baited with Amate mature green mangoes was significantly higher than that captured in traps baited with Coche and Ataulfo fruits. There was no significant difference between the number of flies captured in traps baited with Coche or Ataulfo mangoes. Gas chromatography‐mass spectrometry analysis of mango fruit volatiles identified 24, 22, and 19 compounds for Amate, Ataulfo, and Coche mango cultivars, respectively. A principal component analysis of the volatiles revealed that the Amate mango was more distant from the Ataulfo mango, and the latter cultivar was closer to the Coche mango. The compounds myrcene, α‐pinene, β‐selinene, and trans‐β‐ocimene were the most abundant in Amate mangoes, whereas 3‐carene, β‐selinene, terpinolene, and α‐pinene were the predominant compounds of Ataulfo cultivars. In the Coche mango, the predominant compounds were 3‐carene, β‐selinene, terpinolene, and limonene. Traps baited with a blend of myrcene, α‐pinene, and trans‐β‐ocimene captured more A. obliqua females and males than control traps. Flies were more attracted to the Super Q volatile extracts of Amate mango than to the three‐component blend formulated in a ratio of 1:1:1. However, there was no significant difference between the number of flies caught by traps baited with Amate mango extracts and that caught by traps baited with the three‐blend component when this was formulated according to the relative proportions in the mango extracts. Traps baited with myrcene, the major component, caught fewer flies than traps baited with Amate mango extracts.     

Comparison of two synthetic food-odor lures for captures of feral Mexican fruit flies (Diptera: Tephritidae) in Mexico and implications regarding use of irradiated flies to assess lure efficacy

Feral Mexican fruit flies, Anastrepha ludens (Loew) (Diptera: Tephritidae), were trapped in a citrus orchard in Mexico by using two types of synthetic food-odor lures, the AFF lure (Anastrepha fruit fly lure, APTIV, Inc., Portland, OR) and the BioLure (two-component MFF lure, Suterra LLC, Inc., Bend, OR). In Multilure traps (Better World Manufacturing, Inc., Miami, FL) containing water, BioLures captured about the same numbers of flies as AFF lures. In Multilure traps containing antifreeze solution, BioLures captured 2 and 5 times more flies than AFF lures in two experiments. BioLures, and AFF lures did not differ in attractiveness when used on sticky traps (Intercept trap, APTIV, Inc.; and sticky cylinder trap). Multilure traps captured >4 times as many flies as sticky traps with the exception that captures of females did not differ between Multilure and sticky traps baited with AFF lures. The percentage of females captured in Multilure traps was greater when traps were baited with BioLures compared with AFF lures, but the reverse was true for sticky traps. Sticky cylinder traps captured a higher percentage of females than Multilure traps. The most effective trap/lure combination was the Multilure trap baited with BioLure and antifreeze. In comparison with tests of these two lures in Texas, results were similar for Multilure traps, but they differed for sticky cylinder traps in that AFF lures were consistently more attractive than BioLures in Texas, but not in Mexico.     

Efficacy of 1,4-diaminobutane (putrescine) in a food-based synthetic attractant for capture of Mediterranean and Mexican fruit flies (Diptera: Tephritidae)

Field trials were conducted in Guatemala to evaluate the importance of 1,4 diaminobutane (putrescine) in traps baited with ammonium acetate, trimethylamine, and putrescine. For the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), there were no differences in percentage of females captured in coffee and citrus or in percentage of males captured in citrus in traps with ammonium acetate and trimethylamine lures (females in coffee, 26.4 +/- 6.27%; females in citrus, 35.7 +/- 5.35%; males in citrus, 37.7 +/- 7.48%) versus ammonium acetate, trimethylamine, and putrescine lures (females in coffee, 36.6 +/- 9.64%; females in citrus, 41.1 +/- 5.18%; males in citrus, 37.1 +/- 6.09%). Percentage of males captured in coffee was reduced significantly when putrescine was not used with the ammonium acetate and trimethylamine (39.9 +/- 4.34 versus 31.6 +/- 5.29%). Lower percentages were captured in traps baited with ammonium acetate and putrescine, and the lowest percentages were captured in traps baited with putrescine and trimethylamine. When population level as indicated by capture in traps baited with ammonium acetate, trimethylamine, and putrescine was considered, a higher percentage of C. capitata males were captured in traps baited with all three components when one or more flies per trap per day were captured in coffee, and a higher percentage of females were captured when less than one fly per trap per day was captured in citrus. Percentage of the Mexican fruit fly, Anastrepha ludens (Loew), captured was significantly higher in traps baited with ammonium acetate and putrescine and significantly lower in traps baited putrescine and trimethylamine than in all other treatments. Results indicate that putrescine may be deleted when monitoring established populations of C. capitata but should be used in traps used to monitor A. ludens or to detect new infestations of C. capitata.     

Olfactory response of Anastrepha striata (Diptera: Tephritidae) to guava and sweet orange volatiles

The behavioral responses of virgin and mated female Anastrepha striata Schiner (Diptera: Tephritidae) to guava (Psidium guajava L.) or sweet orange (Citrus sinensis L.) were evaluated separately using multilure traps in two‐choice tests in field cages. The results showed that flies were more attracted to guava and sweet orange volatiles than to control (unbaited trap). The physiological state (virgin or mated) of females did not affect their attraction to the fruit volatiles. Combined analysis of gas chromatography coupled with electroantennography (GC‐EAD) of volatile extracts of both fruits showed that 1 and 6 compounds from orange and guava, respectively elicited repeatable antennal responses from mated females. The EAD active compounds in guava volatile extracts were identified by gas chromatography‐mass spectrometry (GC‐MS) as ethyl butyrate, (Z)‐3‐hexenol, hexanol, ethyl hexanoate, hexyl acetate, and ethyl octanoate. Linalool was identified as the only antennal active compound in sweet orange extracts. In field cage tests, there were no significant differences between the number of mated flies captured by the traps baited with guava extracts and the number caught by traps baited with the 6‐component blend that was formulated according to the relative proportions in the guava extracts. Similar results occurred when synthetic linalool was evaluated against orange extracts. From a practical point of view, the compounds identified in this study could be used for monitoring A. striata populations.     

Attractiveness to Anastrepha ludens (Diptera: Tephritidae) of plant essential oils and a synthetic food-odour lure

Abstract:  Experiments were conducted in a citrus orchard to investigate the attractiveness of 26 plant essential oils individually and in combination with a synthetic food odour lure to the Mexican fruit fly, Anastrepha ludens Loew. Anise, rose/grape seed, and tea tree oils were more attractive than unbaited traps but none approached the attractiveness of Advanced Pheromone Technologies' AFF lure, a synthetic food-odour lure that emits several nitrogenous chemicals attractive to this fly. Traps baited with most of the oils were less attractive than unbaited traps. Rose/grape seed oil and pure-rose oil enhanced attractiveness of AFF lures to both males and females by about 68%. Grape seed oil did not enhance the attractiveness of AFF lures demonstrating that rose oil was the active component of the rose/grape seed oil. No other oil enhanced attractiveness of AFF lures and most decreased attraction to AFF lures. The possibility that highly attractive chemicals may be present in rose oil as minor components is discussed. Traps baited with the combination of clove bud oil and the AFF lure captured only 3% as many flies as traps baited only with the AFF lure indicating that clove bud oil is highly repellent to Mexican fruit flies.     

Evaluation of double-decker traps for emerald ash borer (Coleoptera: Buprestidae)

Improved detection tools are needed for the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive forest insect from Asia that has killed millions of ash (Fraxinus spp.) trees in North America since its discovery in Michigan in 2002. We evaluated attraction of adult A. planipennis to artificial traps incorporating visual (e.g., height, color, silhouette) and olfactory cues (e.g., host volatiles) at field sites in Michigan. We developed a double-decker trap consisting of a 3-m-tall polyvinyl pipe with two purple prisms attached near the top. In 2006, we compared A. planipennis attraction to double-decker traps baited with various combinations of manuka oil (containing sesquiterpenes present in ash bark), a blend of four ash leaf volatiles (leaf blend), and a rough texture to simulate bark. Significantly more A. planipennis were captured per trap when traps without the rough texture were baited with the leaf blend and manuka oil lures than on traps with texture and manuka oil but no leaf blend. In 2007, we also tested single prism traps set 1.5 m above ground and tower traps, similar to double-decker traps but 6 m tall. Double-decker traps baited with the leaf blend and manuka oil, with or without the addition of ash leaf and bark extracts, captured significantly more A. planipennis than similarly baited single prism traps, tower traps, or unbaited double-decker traps. A baited double-decker trap captured A. planipennis at a field site that was not previously known to be infested, representing the first detection event using artificial traps and lures. In 2008, we compared purple or green double-decker traps, single prisms suspended 3-5 m above ground in the ash canopy (canopy traps), and large flat purple traps (billboard traps). Significantly more A. planipennis were captured in purple versus green traps, baited traps versus unbaited traps, and double-decker versus canopy traps, whereas billboard traps were intermediate. At sites with very low A. planipennis densities, more A. planipennis were captured on baited double-decker traps than on other traps and a higher percentage of the baited double-decker traps captured beetles than any other trap design. In all 3 yr, peak A. planipennis activity occurred during late June to mid-July, corresponding to 800-1200 growing degree-days base 10 degrees C (DD10). Nearly all (95%) beetles were captured by the end of July at approximately 1400 DD10.     

Volatile host fruit odors as attractants for the oriental fruit fly (Diptera: Tephritidae)

We examined the responses of oriental fruit flies, Bactrocera dorsalis Hendel, to the odors of different stages and types of fruit presented on potted trees in a field cage. Females were most attracted to odors of soft, ripe fruit. Odors of common guava were more attractive to females than papaya and starfruit, and equally as attractive as strawberry guava, orange, and mango. In field tests, McPhail traps baited with mango, common guava, and orange captured equal numbers of females. Traps baited with mango were compared with 2 commercially available fruit fly traps. McPhail traps baited with mango captured more females than visual fruit-mimicking sticky traps (Ladd traps) and equal numbers of females as McPhail traps baited with protein odors. Results from this study indicate that host fruit volatiles could be used as lures for capturing oriental fruit flies in orchards.     

Capture of Mediterranean fruit flies (Diptera: Tephritidae) in dry traps baited with a food-based attractant and Jackson traps baited with trimedlure during sterile male release in Guatemala

Captures of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in Jackson traps baited with trimedlure were compared with captures in cylindrical open-bottom dry traps baited with a food-based synthetic attractant (ammonium acetate, putrescine, and trimethylamine). Tests were conducted in Guatemala during a sterile male release program in an area where wild flies were present in low numbers. More wild and sterile females were captured in food-based traps, and more wild and sterile males were captured in trimedlure traps. The food-based traps captured almost twice as many total (male plus female) wild flies as the trimedlure traps, but the difference was not significant. Females made up approximately 60% of the wild flies caught in the food-based attractant traps; the trimedlure traps caught no females. The ratio of capture of males in trimedlure traps to food-based traps was 6.5:1 for sterile and 1.7:1 for wild flies. Because fewer sterile males are captured in the food-based traps, there is a reduction in the labor-intensive process of examining flies for sterility. The results indicate that traps baited with food-based attractants could be used in place of the Jackson/trimedlure traps for C. capitata sterile release programs because they can monitor distributions of sterile releases and detect wild fly populations effectively; both critical components of fruit fly eradication programs by using the sterile insect technique.     

Whole body extract of Mediterranean fruit fly males elicits high attraction in virgin females

The search for effective female attractants emanating from the host or body of fruit flies has been an area of intensive research for over three decades. In the present study, bodies of male Mediterranean fruit flies, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), were extracted with diethyl ether or methanol and subjected to gas chromatography–mass spectrometry. Analysis revealed substantial qualitative and quantitative differences between males from a laboratory culture and wild males captured alive in an orchard. Most notably, the hydrocarbon sesquiterpene (±)‐α‐copaene, which is known to be involved in the sexual behaviour of the species, was found in substantial amounts in wild males, but was not detected in laboratory males. In laboratory tests, 15 laboratory or wild male equivalents of diethyl ether extracts or combined diethyl ether and methanol extracts, or, to a lesser extent, methanol extracts alone, were found to attract virgin females. In a citrus orchard, traps baited with combined diethyl ether and methanol extracts of wild males attracted significantly more virgin females than traps baited with various doses of pyranone or blends of other compounds identified in the extracts or reported in the literature, such as ethyl acetate, ethyl‐(E)‐3‐octenoate, and 1‐pyrroline. Traps baited with blends of compounds, however, displayed substantial attractiveness compared to control (non‐baited) traps. These results are important for better understanding the mating system of C. capitata as well as for further improving existing monitoring and control systems.     

Improving monitoring tools for spotted wing drosophila,Drosophila suzukii

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) were trapped in the field using colored plastic sphere traps coated with insect Tangle‐trap. Red and black spheres captured significantly more D. suzukii than white spheres. Translucent deli‐cup traps deployed in cherry orchards and baited with yeast, the Alpha Scents lure, or the Scentry lure captured significantly more flies than the Trécé lure and Suzukii bait; all attractants had poor selectivity for D. suzukii. No‐choice evaluations of attractants conducted in field cages corroborated the cherry orchard field study, though translucent deli‐cup traps provisioned with the yeast bait captured significantly more flies than those baited with the Alpha Scents lure. Red sphere traps baited with the Scentry lure captured 3–6× more flies than the deli‐cup trap baited with the same lure, and 3–4× more flies than the deli‐cup trap baited with yeast bait, demonstrating that a trap integrating both visual and olfactory cues is a superior tool for monitoring D. suzukii. Moreover, this simple sticky, dry trap design requires far less labor and maintenance than does a liquid‐based deli‐cup trap.     

Evaluation of synthetic food-based attractants for female Mediterranean fruit flies (Dipt., Tephritidae) in McPhail type traps

During summer 1997 field experiments were conducted on the island of Chios, Greece, to compare captures of female Mediterranean fruit flies (medflies), Ceratitis capitata (Wiedemann), in traps baited with either synthetic female-targeted lures or a standard protein bait (NuLure and borax). The synthetic lures contained ammonium acetate,1,4 diaminobutane (putrescine), and trimethylamine. Two trap types (International Pheromone's McPhail Trap (IPMT) and the Tephri trap) were tested as either wet or dry. Wet IPMT traps baited with the synthetic attractants were the most attractive of all trap combinations tested and captured 2.1 times more female medflies and 1.8 times more total medflies than traps baited with NuLure and borax. Traps containing the synthetic attractant captured approximately 4.6 times fewer nontarget insects than NuLure baited traps. Vapona used in IPMT traps was repellent to medflies and dry traps with lower concentrations of Vapona were approximately 1.5 times less attractive to female medflies than traps containing water. Even with a decrease in attractiveness, the dry traps were significantly more effective for females and more practical for mass trapping and monitoring than the currently used traps baited with protein solutions.     

Effective sampling range of a synthetic protein-based attractant for Ceratitis capitata (Diptera: Tephritidae)

Studies were conducted in Honduras to determine effective sampling range of a female-targeted protein-based synthetic attractant for the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Multilure traps were baited with ammonium acetate, putrescine, and trimethylamine lures (three-component attractant) and sampled over eight consecutive weeks. Field design consisted of 38 traps (over 0.5 ha) placed in a combination of standard and high-density grids to facilitate geostatistical analysis, and tests were conducted in coffee (Coffea arabica L.),mango (Mangifera indica L.),and orthanique (Citrus sinensis X Citrus reticulata). Effective sampling range, as determined from the range parameter obtained from experimental variograms that fit a spherical model, was approximately 30 m for flies captured in tests in coffee or mango and approximately 40 m for flies captured in orthanique. For comparison, a release-recapture study was conducted in mango using wild (field-collected) mixed sex C. capitata and an array of 20 baited traps spaced 10-50 m from the release point. Contour analysis was used to document spatial distribution of fly recaptures and to estimate effective sampling range, defined by the area that encompassed 90% of the recaptures. With this approach, effective range of the three-component attractant was estimated to be approximately 28 m, similar to results obtained from variogram analysis. Contour maps indicated that wind direction had a strong influence on sampling range, which was approximately 15 m greater upwind compared with downwind from the release point. Geostatistical analysis of field-captured insects in appropriately designed trapping grids may provide a supplement or alternative to release-recapture studies to estimate sampling ranges for semiochemical-based trapping systems.     

Antagonist effects of non-host fruit volatiles on discrimination of host fruit by Rhagoletis flies infesting apple (Malus pumila), hawthorn (Crataegus spp.), and flowering dogwood (Cornus florida)

In previous flight‐tunnel tests Rhagoletis pomonella (Walsh) (Diptera: Tephritidae) flies originating from domestic apple (Malus pumila), hawthorn (Crataegus spp.), and flowering dogwood (Cornus florida), displayed greater numbers of upwind flights to blends of volatiles identified from their natal fruit compared to non‐natal fruit. Here, we show that when certain non‐host volatiles were added to the host blend, significantly fewer apple, hawthorn, and dogwood flies exhibited sustained upwind flight to the source. Specifically, the upwind flight of apple flies to the apple blend was significantly antagonized by the addition of the hawthorn or dogwood blends, the addition of 3‐methylbutan‐1‐ol alone (a key volatile for hawthorn and dogwood flies), or the combination of 3‐methylbutan‐1‐ol and another key dogwood volatile, 1‐octen‐3‐ol. Similarly, the upwind flight of dogwood and hawthorn flies to their respective natal blends was antagonized by the addition of the apple blend or the key apple volatile butyl hexanoate. Experiments were also conducted to determine whether non‐natal fruit volatiles could disrupt the close‐range flight response of flies to the visual stimulus of fruit alone, represented by an odorless red sphere. Tests with apple‐origin flies showed that when the hawthorn blend, the dogwood blend, or the key antagonist volatiles from each (3‐methylbutan‐1‐ol and 1‐octen‐3‐ol) were added to a red sphere fruit mimic, significantly lower proportions of flies were captured, compared with captures when no odor was present. Our results support the hypothesis that agonist and antagonist properties of fruit volatiles can play an important role in host recognition/discrimination by Rhagoletis flies.     

Evaluation of yellow rectangle traps coated with hot melt pressure sensitive adhesive and sticky gel against Rhagoletis indifferens (Diptera: Tephritidae)

Sticky yellow rectangle traps have been used for many years to capture Rhagoletis (Diptera: Tephritidae) fruit flies. Traditional sticky yellow traps are coated with a sticky gel (SG) that can leave residues on the hands of users. An alternative to SG on traps are hot melt pressure sensitive adhesives (HMPSAs), which are less messy. The main objective here was to evaluate two rectangle traps of two yellow colors, the Alpha Scents Yellow Card coated with HMPSA (Alpha Scents, West Linn, OR), and the Pherocon AM trap coated with SG (Pherocon; Trécé, Adair, OK), for capturing western cherry fruit fly, Rhagoletis indifferens Curran. Flies captured on both traps and held in the laboratory and field did not escape their surfaces. Flies caught on HMPSA were damaged when removed from traps without citrus solvent, whereas flies caught on SG could be removed intact without solvent. In field tests, Alpha Scents traps baited with an ammonium bicarbonate lure captured 1.4-2.2 times more R. indifferens than Pherocon traps baited with the same lure. Results of an experiment that eliminated differences in surface sticky material type, overall size, and surface sticky area between Alpha Scents and Pherocon traps suggested, although did not show conclusively, that more flies were caught on the Alpha Scents than Pherocon traps because of their different yellow color and/or lower fluorescence and not the HMPSA. Overall, the Alpha Scents trap is a viable alternative to the Pherocon trap for detecting R. indifferens.     

Plants,microbes, and odorants involved in host plant location by a specialist moth: who's making the message?

The grape berry moth (GBM), Paralobesia viteana (Clemens) (Lepidoptera: Tortricidae), is a specialist pest insect of cultivated grape, Vitis spp. (Vitaceae), in the eastern USA. A blend of volatile compounds has been isolated from plant material that attracts female GBM in the flight tunnel and field. However, the origin of the volatile cue is potentially complicated by the presence of microbes (bacteria and fungi) living on the surface of the plant. Microbial volatile organic compounds can affect insect behavior, and therefore must be considered to fully understand olfaction‐mediated behaviors. We report here the chemical and behavioral analysis of the volatile profiles produced from both the sanitized and control shoot treatments. The sanitization treatment removed 96.4% of the surface microbes up to 24 h, covering the duration of the behavioral assays and volatile collections. Overall, the surface microbes did not significantly contribute to the volatile profile of the grape shoots, as all of the peaks in the volatile profile of sanitized shoots were found in the profile of control shoots. In flight tunnel assays, female GBM displayed the same level of upwind oriented flight to sanitized shoots (flew upwind 57.4%, landed 30.9%) as they did to control shoots (flew upwind 57.8%, landed 31.0%), suggesting further that surface microbes did not contribute to the production of the previously identified blend of behaviorally active volatiles for GBM.     

Identification of the sex pheromone of Copitarsia decolora (Lepidoptera: Noctuidae)

Chemical and electrophysiological analyses and field trials were used to identify the female sex pheromone of Copitarsia decolora (Guenée) (Lepidoptera: Noctuidae). Coupled gas chromatographic-electroantennographic detection (GC-EAD) analysis of the female gland extract showed the presence of two EAD-active peaks, which were identified by GC-mass spectrometric (MS) analysis as (Z)-9-tetradecenyl acetate (Z9-14:Ac) and (Z)-9-tetradecenol (Z9-14:OH). The field evaluation of the EAD-active compounds indicated that traps baited with either Z9-14:Ac or Z9-14:OH caught few males. In contrast, traps baited with the binary blend of both components caught significantly more males than traps baited with the single compounds. Captures in traps baited with a mixture of Z9-14:Ac and Z9 -14:OH at 4:1, 10:1, and 100:1 ratios were not significantly different from the catches in traps baited with virgin females. Few males were captured in traps baited with a blend of Z9-14:Ac and Z9-14:OH at 1:4, 1:10, and 1:100 ratios.     

Behaviour of tsetse flies (Glossina) in host odour plumes in the field

ABSTRACT. In Zimbabwe, studies were made of the responses of Glossina pallidipes Austen and G.morsitans morsitans Westwood to artificial host odour using an incomplete ring of electrocuting nets. In a plume of synthetic host odour tsetse flew generally upwind, with 50–60% flying within 35^o of due upwind. More than 80% of tsetse flew at < 50 cm above ground level. Upon losing contact with odour they executed a reverse turn within about 2 m, and upon regaining contact they turned upwind. There were no clear differences in the responses of G.m.morsitans and G.pallidipes. Using electrocuting nets lying horizontally on the ground it was found that tsetse landed in the vicinity of the odour source, the propensity to land being greater for G.pallidipes than for G.m, morsitans , greater for immature than mature flies, and greater for males than females.     

Distant olfactory response of the cabbage seed weevil, Ceutorhynchus assimilis, to oilseed rape odour in the field

Abstract. The olfactory orientation of adult cabbage seed weevils (Ceutorhynchus assimilis Payk.) from a distance of 20 m to extracts of oilseed rape (Brassica napus L.) was studied in the field using mark–release–recapture experiments. Male and female weevils dispersed upwind from the centre of a circular array of traps baited with Oilseed rape extracts. In the absence of host-plant odour, female weevils dispersed randomly, and male weevils downwind. Percentage recapture of weevils was significantly greater in traps baited with rape flower than rape leaf extracts. Significantly fewer weevils were recaptured in unbaited traps compared to traps baited with rape flower or leaf extracts. We suggest that seed weevils can use odour-mediated upwind anemotaxis to locate their host-plants from distances of at least 20 m.     

Field evaluation of three-component solid food-based dispenser versus torula yeast for capturing Mediterranean and oriental fruit flies (Diptera: Tephritidae)

Certain species of true fruit flies (Diptera: Tephritidae) are worldwide pests of fruits and vegetables, and many countries operate trapping programs to detect and monitor invasions. Torula yeast-borax (TYB) solution is a widely used food bait, although its effective field longevity is relatively short (1–2 weeks). This led to the development of a synthetic cone-shaped food dispenser that contains ammonium acetate, putrescine, and trimethylamine. The food cone has received limited testing, and the objective of this study was to compare captures of the Mediterranean fruit fly (Ceratitis capitata (Wiedemann)) and the oriental fruit fly (Bactrocera dorsalis (Hendel)) in traps baited with the fresh TYB solution versus traps baited with fresh or weathered food cones. Captures showed a female bias for both baits and both species. For C. capitata, fresh food cones generally attracted more individuals than fresh TYB. Weathered food cones attracted similar or greater numbers of medflies than TYB for the initial two weeks, but food cones weathered for 4 or 6 weeks attracted fewer flies than TYB. For B. dorsalis, TYB-baited traps captured more females than fresh or weathered food cone-baited traps in each of six weekly sampling periods, and the differences were statistically significant in weeks 1–4. In a release-recapture experiment, both C. capitata and B. dorsalis were captured in higher numbers in traps baited with fresh TYB than those baited with food cones weathered for 0 (fresh) to 6 weeks. The implications of these results for fruit fly surveillance are discussed.