Effectiveness of thiamethoxam-coated spheres against blueberry maggot flies (Diptera: Tephritidae)

Studies were conducted to evaluate the mortality of blueberry maggot, Rhagoletis mendax Curran, flies exposed to thiamethoxam- and imidacloprid-coated biodegradable (8-cm-diameter) red spheres, under both laboratory and field conditions. Laboratory studies with spheres coated with 0.1-2.0% (AI) of thiamethoxam indicated that they are effective against R. mendax; however, no dose-dependent response was observed. Studies on the effect of visitation time on thiamethoxam-coated spheres showed a decrease in R. mendax mortality as the duration of visitation time decreased from 60 to 10 s. Under field conditions, significantly more flies were captured on Plexiglas panes below the 2% (AI) thiamethoxam-coated spheres when compared with similar panes below untreated spheres. In field evaluations of thiamethoxam- and imidacloprid-coated spheres, imidacloprid-coated spheres (2.0% [AI]) were found to be significantly more effective than thiamethoxam-coated spheres (0.5-4.0% [AI]). Field trials to characterize the levels of mortality associated with aging pesticide-coated spheres revealed that the effectiveness of treated spheres decreased with increasing age of sphere, and this reduction in effectiveness is greater in thiamethoxam-coated spheres than in imidacloprid-coated spheres. These results provide comparative data on the effectiveness of thiamethoxam- and imidacloprid-coated spheres and support the potential of using pesticide-treated spheres for control of blueberry maggot flies.     

Effect of trap position, habitat, and height on the capture of pepper maggot flies (Diptera: Tephritidae)

Trapping results indicate that pepper maggot, Zonosemata electa (Say), flies occupy tree canopies adjacent to fields when not on host plants. Several in- and near-field trap positions were used to find a reliable monitoring system for adult pepper maggots. Traps baited with liquid ammonium hydroxide (Stills-style trap), hung in the canopy of trees on the edges of pepper fields, caught significantly more Z. electa flies than when positioned lower along the treeline or in the field. In a second experiment, significantly more pepper maggot flies were captured in sugar maples compared with choke cherry trees, which indicates a pest preference for certain nonhost habitats. The lowest trap height tested (2.1 m) failed to capture Z. electa flies in either tree species when the pest population level was low. These studies demonstrated that pepper maggot flies can be reliably detected with Stills-style traps positioned at approximately 6.4 m height within the canopy of sugar maple trees adjacent to pepper fields. Fruit oviposition scars also are useful site-specific indicators of pepper maggot presence/absence and may aid in determining if insecticide applications are necessary and in timing sprays.     

Visual and olfactory stimuli and fruit maturity affect trap captures of Oriental fruit flies (Diptera: Tephritidae)

An effective lure-and-kill trap is a potentially important instrument in monitoring and controlling oriental fruit flies, Bactrocera dorsalis (Hendel). A number of experiments were performed in an orchard of commercial guava, Psydium guajava L., to determine how fly captures are affected by combining visual and olfactory stimuli, and by the timing of trap deployment relative to host phenology. Baiting sticky Ladd traps with hydrolyzed liquid protein significantly increased the number of captured flies. Mostly male flies were caught in the absence of mature guava fruit, whereas mostly female flies were caught when ripe fruit was abundant. These results suggest that an effective oriental fruit fly trap should include both visual and olfactory lures, and that proper timing of trap deployment can be an important factor in monitoring female abundance in oriental fruit fly populations.     

Managing the pepper maggot (Diptera: Tephritidae) using perimeter trap cropping

A perimeter trap crop barrier of hot cherry peppers, border-row insecticide applications, and a combination of the two management strategies were evaluated to see if they could protect a centrally located main crop of bell peppers from oviposition and infestation by the pepper maggot, Zonosemata electa (Say). In large plots, the main cash crop of bell peppers was protected from the majority of the oviposition and infestation by all three barriers. The combination sprayed/trap crop barrier provided the best protection against both oviposition and infestation and resulted in over 98% pest-free fruit at harvest. Maggots infested only 1.7% of the main crop fruit when protected by a sprayed or unsprayed trap crop barrier, compared with 15.4% in control plots. The perimeter sprayed/trap crop strategy was employed in three commercial fields in 2000 and 2001. The combination barrier resulted in superior insect control and reduced insecticide use at all commercial locations, compared with the same farms' past history or to farms using conventional and integrated pest management (IPM) methods. Economic analysis showed that the technique is more cost effective and profitable than relying on whole-field insecticide applications to control the pepper maggot. Farmer users were surveyed and found the perimeter trap crop technique simple to use, with many hard-to-measure benefits associated with worker protection issues, marketing, personnel/management relations, pest control and the environment. Use of the perimeter trap crop technique as part of an IPM or organic program can help improve crop quality and overall farm profitability, while reducing pesticide use and the possibility of secondary pest outbreaks.     

Visual responses of apple maggot flies, Rhagoletis pomonella (Diptera: Tephritidae): Orchard studies

Apple maggot flies, Rhagoletis pomonella, were found to be highly responsive to visual stimuli, with maximum responses dependent upon color, shape, and size characteristics of the stimulus. Each sex had a significant preference for yellow 30×40 cm rectangles over green, orange, red, blue, violet, black, white and clear rectangles of the same size. On the other hand, each sex had a significant preference for red, blue, violet, dark organge, and black spheres 7.5 cm in diameter over green, light orange, yellow, white, and clear spheres of the same size. Both sexes had a significant preference for 7.5 cm spheres over equivalent-sized cubes, cylinders and rectangles. As the diameter of a sphere was increased from 7.5 to 45 cm, there was an orderly and significant decrease in the attractiveness of those that were darkcolored (red) but a progressive and significant increase in the attractiveness of those that were yellow. The flies did not congregate on trees with apples or respond strongly to 7.5 cm, darkcolored spheres until they were sexually mature (at least in the case of females). Relative to other colors, females were often significantly more attracted than males to yellow. The attractiveness of an olfactory stimulus eliciting feeding-type reactions was enhanced to a substantial degree when employed in conjunction with a 30×40 cm yellow rectangle, but to only a very slight degree when in conjunction with a 7.5 cm red sphere.Evidence presented suggests the following explanation for these findings. The flies are attracted to large surfaces of yellow because they react to yellow, on the basis of true color discrimination, as if it were foliage on which to find food. On the other hand, they are attracted to small, dark-colored spheres because they react to such spheres as they react to apples, which are the oviposition site and which also appear to serve as a rendezvous site for the sexes in mating activity. Once the flies have arrived on apple trees, they detect apples solely through vision. Red, blue, violet, dark orange, and black small spheres are preferred over small spheres of other colors on the basis that they stand out in strongest contrast against the background and not on the basis of true color discrimination. Large, dark-colored spheres are unattractive because the range of sphere sizes eliciting positive responses is near the size of an apple.These findings have proven useful in designing effective devices for sampling orchard populations of the flies and may also prove useful in fly control.

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Zusammenfassung Imagines von Rhagoletis pomonella reagieren positiv auf visuelle Reize, wobei Farbe, Form und Grösse des Stimulus von ausschlaggebender Bedeutung sind. Beide Geschlechter zeigten in den Versuchen eine signifikante Präferenz für gelbe Rechtecke (30×40 cm), die sie häufiger anflogen als grüne, orange, rote, blaue, violette, schwarze, weisse und farblose Flächen gleicher Grösse. Ebenso zeigte es sich, dass Kugeln von 7.5 cm Durchmesser von den Fliegen eindeutig Kuben, Zylindern und Rechtecken gleicher Grössenordnung für den anflug bevorzugt wurden. Mit zunehmendem Durchmesser der Kugeln von 7.5 cm bis 45 cm konnte eine abnehmende Anziehung von dunkel gefärbten Kugeln, jedoch eine zunehmende Anziehung von gelben Kugeln auf die Fliegen beobachtet werden. Vor der Geschlechtsreife reagierten die Weibchen nicht in ausgeprägtem Maße auf die 7.5 cm dunkel gefärbte grossen Kugeln, sondern wurden mehr als die Männchen von Gelb angezogen. Die Wirkung eines Nahrungsköders wurde in Kombination mit einer gelben Fläche von 30×40 cm signifikant erhöht, während die Kombination des Köders mit einer roten Kugel von 7.5 cm Durchmesser die Anziehung von Weibchen nur unwesentlich erhöhte.Die Resultate lassen sich damit erklären, dass die Fliegen durch gelbe Flächen angezogen werden, weil sie dank Diskriminierung der Farbe auf Gelb reagieren als wäre es Blattwerk, auf dem sich die Nahrungsquellen befinden. Auf der anderen Seite werden sie von dunklen Kugeln in den Dimensionen eines Apfels angezogen, da im Freiland Äpfel Orte für die Eiablage und offenbar Treffpunkte für die Geschlechter darstellen. Sobald die Fliegen den Apfelbaum beflogen haben, orientieren sie sich allein mit dem Gesichtssinn gegen die Früchte. Kleinere rote, blaue, dunkel orange, violette und schwarze Kugeln werden anders gefärbten vorgezogen, weil sie den grössten Kontrast gegenüber dem Hintergrund bilden und nicht auf Grund echter Farbdiskriminierung. Grosse dunkle Kugeln verlieren ihre Wirkung auf die Fliegen, weil nur Kugeln in der Grössenordnung eines Apfels positive Reaktionen auslösen.Diese Befunde haben sich als nützlich erwiesen in der Ausarbeitung von Sammelmethoden für Freilandpopulationen und dürften auch in der Bekämpfung der Apfelfliegen Anwendung finden.

     

Protection of fruit against infestation by apple maggot and blueberry maggot (Diptera: Tephritidae) using compounds containing spinosad

Two insecticide formulations containing the naturalyte insecticide spinosad, GF-120 Fruit Fly Bait and SpinTor 2 SC, were compared for control of apple maggot, Rhagoletis pomonella (Walsh), and blueberry maggot, Rhagoletis mendax Curran. In 2002 and 2003, larval infestation in blueberries and apples was significantly lower in plots treated with GF-120 (spinosad bait) or SpinTor than in untreated control plots. Fruit fly infestation in apples was reduced by 67% in 2002 after weekly application of GF-120 for 6 wk. Six weeks of GF-120 treatment reduced infestation in blueberries by 85% in 2002 and 98% in 2003. Plots treated weekly with the bait component of GF-120 for 6 wk had significantly higher infestation of blueberry maggot larvae compared with untreated plots in 2002. Observations of wild R. mendax flies revealed that similar numbers of flies landed on blueberry foliage treated with spinosad bait, the bait component alone, or water droplets. However, flies on spinosad bait and bait treated plants spent significantly more time within 5 cm of the treatment droplets compared with control (water) droplets. Overall, the results demonstrate a high degree of efficacy of baited spinosad formulations against these key pests of temperate fruit and suggest that GF-120 is an arrestant for foraging flies.     

Comparative effectiveness of different insecticides for organic management of blueberry maggot (Diptera: Tephritidae)

Laboratory and field assays using insecticides for organic pest management were conducted on the blueberry maggot, Rhagoletis mendax Curran. Topical exposure of flies to spinosad (Entrust), pyrethrum (PyGanic 1.4 EC), azadirachtin (Aza-Direct), and phosmet (Imidan 70-W) resulted in significantly higher mortality compared with the water control after 2 and 24 h. After 24 h, there were no significant differences in fly mortality among treatments of Entrust, PyGanic, or Imidan, whereas fly mortality to Aza-Direct was significantly lower. Another laboratory assay evaluated mortality of flies after residual exposure to these insecticides on leaves, after 24 and 48 h. In this assay, there were no significant differences in fly mortality after 48 h among treatments of PyGanic, Aza-Direct, and the water control, whereas significantly higher fly mortality resulted from exposure to Entrust and Imidan. A repellency assay found no measurable effects of Aza-Direct. Large-scale field trials found no treatment effect for number of adults of the blueberry maggot captured in sticky traps; however, there were significantly lower levels of fruit-infesting larvae in treated plots compared with the untreated control. Spinosad bait (GF-120 NF Naturalyte Fruit Fly Bait), Entrust, and PyGanic were not different from imidacloprid (Provado 1.6 F). However, there was a significantly higher infestation in the plot treated with azadirachtin (Agroneem) compared with Provado. Overall, the insecticides evaluated in these trials showed good ability to control blueberry maggot, suggesting that they can be incorporated in a blueberry maggot management program under organic standards.     

Emergence of blueberry maggot flies (Diptera: tephritidae) from mulches and soil at various depths

Control of blueberry maggot, Rhagoletis mendax Curran, typically is achieved with insecticides targeting adult flies before females oviposit in ripening fruit. Management strategies targeting other life stages have received less attention. We tested effects of compost or pine needle mulches on emergence of blueberry maggot flies under laboratory and field conditions. Few flies emerged from pupae that were buried under 20 cm of pine needles in all experiments, but burial in 20 cm of compost did not always result in low fly emergence. Burial of pupae in 5 cm of compost or pine needles did not reduce fly emergence compared with 1 cm in soil. Low emergence with increased mulch depth appeared to be primarily because of failure of flies to ascend to the surface after they exited puparia. Low emergence also was associated with high moisture levels causing rotten, discolored pupae, particularly in the laboratory in compost. No flies emerged from pupae buried in 1 cm of pine needles in the field. In this case no flies exited puparia, likely because high temperatures (>30°C) at the surface killed pupae. Thus, mulch application under highbush blueberries (Vaccinium corymbosum L.) after maggots drop from berries can reduce emergence success of flies from buried pupae, but the level of control will depend on mulch depth and may vary with rainfall and temperature.     

Feeding activity and attraction of blueberry maggot (Diptera: Tephritidae) to protein baits, ammonium acetate, and sucrose

Attraction and feeding assays were conducted on blueberry maggot, Rhagoletis mendax Curran, to three protein baits, ammonium acetate, and sucrose. Flies fed significantly longer on concentrations of 25 and 50% SolBait than they did on any of the concentrations tested for Nu-Lure, AY50% (Mauri Yeast Australia), or a water control. The number of flies arriving at SolBait in an attraction assay was significantly higher than for Nu-Lure and a water control but was not different from AY50%. Flies fed less on aqueous solutions of 1 and 4% ammonium acetate, a known fruit fly attractant, than they did on either 0.25% ammonium acetate or water. Aqueous concentrations of 8, 16, and 32% sucrose elicited greater feeding responses from flies than either 4% sucrose or water. These findings suggest that SolBait is a superior protein bait based on attraction and feeding assays. Development of alternative baits should contain at least 8% sucrose, as a significant feeding stimulant, and some amount of ammonium acetate as an attractant. Future work should determine whether the feeding deterrence of ammonium acetate could be reduced or even eliminated in the presence of sucrose.     

Evaluation of trap deployment patterns for behavioural control of apple maggot flies (Dipt., Tephritidae)

Abstract: We evaluated three different deployment patterns of sticky red sphere traps, baited with a five-component blend of synthetic attractive fruit odour and placed on perimeter apple trees bordering adjacent habitat (front-row trees), for control of apple maggot flies, Rhagoletis pomonella (Walsh), in small plots of apple trees (about 30 × 30 m) in Massachusetts commercial apple orchards. Degree of fly penetration from front-row to interior apple trees was assessed for R. pomonella of wild origin and for marked adults released in habitats adjacent to front-row trees. Traps placed 10  and 5 m apart on front-row trees or grouped on a single central front-row tree performed as well as grower-applied insecticide sprays in preventing penetration of plots by wild and released flies and in preventing fruit injury . This was equally true for plots whose front-row trees consisted of cultivars comparatively susceptible to apple maggot as for plots whose front-row trees were comprised of comparatively tolerant cultivars. It was also true for each seasonal period during which sampling for treatment performance occurred.     

Effect of high-carbon dioxide atmospheres on infestations of apple maggot (Diptera: Tephritidae) in apples

Short-term storage regimens containing elevated atmospheres of carbon dioxide (CO2) were evaluated for their ability to disinfest newly harvested 'McIntosh' apples of apple maggot, Rhagoletis pomonella (Walsh). Infested fruits containing newly laid eggs were either placed directly into the high-CO2 atmosphere at 10 degrees C to expose this life stage, or else held first for 7 d at room temperature, to allow development to the neonate larval stage. Treatment combinations consisted of three different CO2 levels (10.6, 14.9, and 19.0% CO2) and two periods of exposure (7 and 14 d). Apple maggot eggs subjected to the treatments always exhibited some survival, which was lower for the 14-d than the 7-d exposure periods. In contrast, newly hatched larvae were less able to survive the treatments. The 7-d exposure allowed low levels of survival of this life stage, but virtually none survived the 14-d exposure period. To determine the age at which eggs become more susceptible to high-CO2 atmospheres, infested fruits containing eggs three or 3d old were submitted to a 14-d exposure to 19.0% CO2. Survival of 3-d old eggs was similar to that of eggs exposed at an age of 1 d or less, but this dropped to near zero for 5-d old eggs, indicating an increase in susceptibility sometime during the 3-5-d age range. Fruits exposed to 19.0% CO2 for 14 d were significantly firmer than untreated fruits. No apparent browning, internal breakdown or other fruit defects were detected in any of the treatments.     

Quantifying pepper maggot (Diptera: Tephritidae) oviposition and infestation over time

In 1998 and 1999, pepper maggot flies, Zonosemata electa (Say), were excluded from pepper plants with row covers for 0-6 wk after initial oviposition was detected. The proportion of oviposition attempts (scars) and larval infestation that occurred each week and the cumulative oviposition and infestation over time were determined. Due to environmental factors, initial oviposition was delayed, and the numbers of oviposition scars on fruit and flies caught on traps were lower in 1998 than in 1999. The proportions of scarred or infested fruit were low (< 8% of total) during the first 7 d after the pest was detected each year. Oviposition peaked 8-14 d after beginning in 1998, but not until 21-28 d after the initial scar was detected in 1999. Because systemic insecticides tend to provide control of adults and most hatching larvae, it may be possible to delay the initial insecticide application for up to a week after oviposition commences and still minimize fruit damage. There was no association with either year between the proportion of flies captured on traps and the proportion of oviposition scars on fruit the same week or 1 and 2 wk later.     

Effect of altitude on seasonal flight activity of Rhagoletis cerasi flies (Diptera: Tephritidae)

The effect of altitudinal variation on the seasonal flight activity of Rhagoletis cerasi (Linnaeus) flies was evaluated along an altitudinal gradient from 150 to 1170 m in Mount Uludag, northwestern Turkey. The predicted dates of fly emergence, flight duration and dates of 5%, 50% and 95% cumulative fly catches at various altitudes were estimated from a degree-day model. Degree-day predictions were compared with those obtained from observations made with yellow sticky traps. The observed and predicted dates of appearance of adults were delayed by 1.4 and 2.0 days for every 100 m increase in altitude, respectively. The delay in phenology events was less at high altitudes than postulated by Hopkins' bioclimatic law, whether observed or predicted. The average absolute difference in predicted and observed dates of cumulative percentage catch of adults was 4.9 and 3.0 days in 1997 and 1998, respectively, but these differences were not significant. Prolonged flight activity was predicted and observed at higher altitudes, but the flight period lasted significantly longer than predicted. The observed flight period varied from 29 to 43 days in 1997 and from 36 to 52 days in 1998 between the lowest and highest altitude on the transect. Altitudinal variation between geographically close locations should be taken into account to properly time monitoring activities and hence to manage R. cerasi populations more effectively.     

Trap position and fruit presence affect visual responses of apple maggot flies (Dipt., Tephritidae) to different trap types

Abstract:  We compared responses of apple maggot flies, Rhagoletis pomonella (Walsh), in a commercial apple orchard in Massachusetts with three different types of visual traps baited with synthetic fruit volatiles. The traps were red spheres, Ladd traps (a rectangular yellow panel between two red hemispheres) and rectangular yellow panels. Traps were placed either in optimal position (D rummond , F.; G roden , E.; P rokopy , R. J., 1984: Environ. Entomol. 13, 232–235.) or sub-optimal position (not surrounded by foliage and fruit from all sides). The study was performed over 3 years. Early in the fruiting season, when apples were small and green, red spheres followed by Ladd traps attracted more flies than yellow panels. Ladd traps were the most sensitive to trap positioning, losing effectiveness when placed in sub-optimal position. Late in the fruiting season, in years yielding crops of large red apples, red spheres in optimal position (surrounded by growing red fruit) lost some effectiveness relative to Ladd traps in optimal position. Red spheres in sub-optimal position were not similarly affected, perhaps because of the lack of fruit in the background. Red sphere performance relative to Ladd traps was re-established after removal of competing fruit from trees at harvest. Because Ladd traps are more expensive to purchase and more difficult to position, red spheres are a better option for commercial growers in eastern North America. Conceivably, loss of capturing power of red spheres because of visual competition from red apples towards harvest could be mitigated by adjusting trap positioning.     

Population dynamics of apple maggot (Diptera: Tephritidae) in south central Pennsylvania

The apple maggot, Rhagoletis pomonella (Walsh), was monitored with baited yellow panels and red spheres in commercial orchards, abandoned orchards, and unsprayed backyard apple trees in 1998 and 1999. Apple maggot adults were captured in all apple habitats, but the capture levels in the abandoned orchards and unsprayed backyard trees tended to be higher than in the commercial orchards. Peak capture occurred between mid-July and late August in both years. Emergence cages seeded with infested fruits were used to investigate bivoltinism, which was observed in both years.     

Irradiation disinfestation of apple maggot (Diptera: Tephritidae) in hypoxic and low-temperature storage

Apple maggot, Rhagoletis pomonella (Walsh), is a quarantine pest of apples, Malus domestica Borkhausen, and pears, Pyrus communis L., shipped from much of the United States and Canada. As such, these fruits shipped from infested areas to uninfested areas must undergo a quarantine disinfestation treatment. The objective of this research was to develop irradiation quarantine treatments against apple maggot considering that fruit hosts may be stored under hypoxic or cold conditions when they are irradiated. Hypoxia increased from 30.5 to 35.7 Gy (17%) the estimated dose to achieve 99% prevention of the full pupal stage from irradiated third instars in apples compared with ambient atmospheres. However, 50 Gy completely prevented the full pupa in 22,360 and 15,530 third instars, respectively, irradiated in apples in ambient and hypoxic atmospheres. There was no difference in development to the full pupal stage in apple maggot third instars held at 1 or 24 degrees C when irradiated with 20 Gy. Because the maximum dose measured when 50 Gy was sought was 57 Gy, the latter should be the dose recommended for quarantine disinfestation of host fruits of the apple maggot. Apples and pears tolerate much higher doses.     

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.