Effectiveness of odor-baited trap trees for plum curculio (Coleoptera: Curculionidae) monitoring in commercial apple orchards in the northeast

The plum curculio, Conotrachelus nenuphar (Herbst), is a key pest of pome and stone fruit in eastern and central North America. For effective management of this insect pest in commercial apple (Malus spp.) orchards in the northeastern United States and Canada, one of the greatest challenges has been to determine the need for and timing of insecticide applications that will protect apple fruit from injury by adults. In a 2004-2005 study, we assessed the efficacy and economic viability of a reduced-risk integrated pest management strategy involving an odor-baited trap tree approach to determine need for and timing of insecticide use against plum curculio based on appearance of fresh egg-laying scars. Evaluations took place in commercial apple orchards in seven northeastern U.S. states. More specifically, we compared the trap-tree approach with three calendar-driven whole-block sprays and with heat-unit accumulation models that predict how long insecticide should be applied to orchard trees to prevent injury by plum curculio late in the season. Trap tree plots received a whole-plot insecticide spray by the time of petal fall, and succeeding sprays (if needed) were applied to peripheral-row trees only, depending on a threshold of one fresh plum curculio egg-laying scar out of 25 fruit sampled from a single trap tree. In both years, level of plum curculio injury to fruit sampled from perimeter-row, the most interior-row trees and whole-plot injury in trap tree plots did not differ significantly from that recorded in plots subject to conventional management or in plots managed using the heat-unit accumulation approach. The amount of insecticide used in trap tree plots was reduced at least by 43% compared with plots managed with the conventional approach. Advantages and potential pitfalls of the bio-based trap tree approach to plum curculio monitoring in apple orchards are discussed.     

3 using odor-baited trap trees as sentinels to monitor plum curculio (Coleoptera: Curculionidae) in apple orchards

In commercial orchards in Massachusetts in 2003, we conducted experiments aimed at developing guidelines for use of perimeter-row trap trees baited with grandisoic acid plus benzaldehyde as sentinels in a practical approach to determining need and timing of insecticide applications against overwintered plum curculios, Conotrachelus nenuphar (Herbst). Evaluations were based on percentages of sampled fruit injured by plum curculio. Trap trees baited with grandisoic acid released at approximately 1 mg/d plus benzaldehyde released at approximately 40 mg/d performed as well as or better than trap trees baited with greater or lesser amounts of these attractants in combination. The distance over which a trap tree baited with such odor was effective in aggregating damage to fruit extended to at least 31-33 m (maximum evaluated) along a perimeter row. Trap trees at corners of orchard blocks were as effective as perimeter-row trap trees midway between corner trees. Within the canopy of a trap tree, damage did not tend significantly to be localized in the vicinity of the odor source but tended to be rather evenly distributed among various sectors of the canopy. Finally, among three candidate thresholds evaluated as a trigger for insecticide application, a threshold of one freshly injured fruit proved better than thresholds of two or four freshly injured fruit out of 50 fruit sampled on a trap tree in assuring that orchard-wide damage would remain below a preset economic injury level of 1%. Our findings lead us to suggest that after a whole-orchard application of insecticide to apple trees in Massachusetts orchards shortly after petal fall, subsequent applications of insecticide against plum curculio can be confined to peripheral-row trees and be driven by a provisional threshold of one freshly injured fruit out of 50 fruit sampled on a perimeter-row trap tree baited with the above-mentioned odor.     

Odor-baited trap trees: a new approach to monitoring plum curculio (Coleoptera: Curculionidae)

We compared a trap approach with a trap-tree approach to determine the need and timing of insecticide applications against overwintered adult plum curculios, Conotrachelus nenuphar (Herbst.), in commercial apple orchards in Massachusetts in 2002. All traps and trap trees were baited with benzaldehyde (attractive fruit odor) plus grandisoic acid (attractive pheromone). Sticky clear Plexiglas panel traps placed at orchard borders, designed to intercept adults immigrating from border areas by flight, captured significantly more adults than similarly placed black pyramid traps, which are designed to capture adults immigrating primarily by crawling, or Circle traps wrapped around trunks of perimeter-row trees, which are designed to intercept adults crawling up tree trunks. None of these trap types, however, exhibited amounts of captures that correlated significantly with either weekly or season-long amounts of fresh ovipositional injury to fruit by adults. Hence, none appears to offer high promise as a tool for effectively monitoring the seasonal course of plum curculio injury to apples in commercial orchards in Massachusetts. In contrast, baiting branches of selected perimeter-row trees with benzaldehyde plus grandisoic acid led to significant aggregation (14-15-fold) of ovipositional injury, markedly facilitating monitoring of the seasonal course of injury to apples. A concurrent experiment revealed that addition of other synthetic fruit odor attractants to apple trees baited with benzaldehyde plus grandisoic acid did not enhance aggregation of ovipositional injury above that of this dual combination. We conclude that monitoring apples on odor-baited trap trees for fresh ovipositional injury could be a useful new approach for determining need and timing of insecticide application against plum curculio in commercial orchards.     

Monitoring plum curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), populations in apple and peach orchards in the mid-Atlantic

We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to four trap types in commercial and unsprayed apple and peach orchards. Trap types included black pyramid and clear Plexiglas panel traps deployed outside the orchard 2 m from the border row, and branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. Bait treatments evaluated in conjunction with each trap type included the synthetic fruit volatile benzaldehyde, the aggregation pheromone grandisoic acid (GA), benzaldehyde in combination with GA, and an unbaited control treatment. In commercial apple orchards, significantly more plum curculio were captured in traps baited with benzaldehyde + GA compared with traps baited with other treatments. Furthermore, significantly more plum curculio were captured by screen traps baited with benzaldehyde + GA compared with unbaited control traps. Significantly more plum curculio were captured by screen traps compared with other trap types in an unsprayed apple orchard. Very few captures were recorded in commercial peach orchards. Dissections of trapped females indicate that bivoltine populations are present in the mid-Atlantic. In general, correlations between timing and amount of trap captures and timing and amount of fruit injury inflicted concurrently or 1 wk after trap captures were very weak for all trap types and bait combinations. Our results agree with previous studies in the northeastern United States in which trap captures are increased by presence of semiochemical baits but fail to serve as reliable tools to determine need for and timing of insecticide application against plum curculio.     

Impact of trap architecture, adjacent habitats, abiotic factors, and host plant phenology on captures of plum curculio (Coleoptera: Curculionidae) adults

Pyramid traps, 2.44 m and 3.66 m in height, were compared with standard-sized pyramid traps, 1.22 m in height, to assess the impact of trap architecture on captures of adult plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in two apple (Malus spp.) orchards and a blueberry (Vaccinium spp.) planting. The effects of adjacent habitat (organic orchard versus wooded areas), abiotic factors, and phenological stages of apple also were assessed to determine whether these variables influenced trap captures. Standard-sized pyramidal traps captured significantly more adults than larger trap variants. In the apple orchards, most adults (70-80%) were captured before petal fall with the exception of blocks adjacent to the organic orchard (25%). Significantly more adults were captured along the edge of an apple orchard (managed using an integrated pest management strategy) facing an organic apple orchard (76%) than along the edge facing wooded areas (24%). There was a significant positive correlation between daily trap captures and mean daily temperatures before petal fall in apple orchards.     

Size of orchard trees as a factor affecting behavioural control of apple maggot flies (Dipt., Tephritidae) by traps

Over a 3-year period (1997–1999), we examined the influence of tree size on effectiveness of traps for behaviourally controlling apple maggot flies, Rhagoletis pomonella (Walsh), in small blocks of trees in Massachusetts commercial apple orchards. Traps were red spheres coated with Tangletrap and baited with an attractive synthetic host fruit odour (butyl hexanoate). Traps were placed 6 m apart on perimeter apple trees of each block and were designed to intercept apple maggot flies immigrating into blocks from unmanaged host trees. Based on captures of adults by unbaited red spheres placed near the centre of each block to monitor degree of adult penetration into the interior and on percentages of fruit injured by apple maggot, traps surrounding blocks of small trees (1.5 m canopy diameter) planted at high density were more effective in controlling apple maggot flies (relative to control obtained by insecticide sprays used in comparison blocks) than were traps surrounding blocks of large trees (3.7 m canopy diameter) planted at low density, with traps surrounding blocks of medium-size trees (2.5 m canopy diameter) planted at medium density generally providing an intermediate level of control.     

Attracticidal spheres for controlling apple maggot flies: commercial-orchard trials

Wooden pesticide-treated red spheres and biodegradable sugar/flour pesticide-treated red spheres were compared with wooden sticky-coated red spheres and insecticide sprays for controlling apple maggot flies, Rhagoletis pomonella(Walsh) (Diptera: Tephritidae), in small blocks of apple trees in Massachusetts commercial orchards in 1997, 1998 and 1999. Pesticide-treated spheres received a coating of 70% latex paint, 20% feeding stimulant (sucrose), and 10% formulated insecticide (containing 20% imidacloprid). To replenish sucrose lost during rainfall, wooden spheres were capped with a disc comprised of hardened sucrose that seeped onto the sphere surface, whereas the surface of sugar/flour spheres received sucrose that seeped from the interior. Each year, each of the 24 perimeter trees of each non-sprayed block received a sphere baited with butyl hexanoate (an attractive component of host fruit odor), with the intent of intercepting immigrating flies. Based on captures of flies on unbaited sticky-coated red spheres placed near the center of each block and on periodic samples of fruit for injury, there was a consistent pattern of treatment performance. Each year, sticky-coated spheres were only slightly less effective than two or three sprays of organophosphate insecticide, sugar/flour pesticide-treated spheres were only slightly less effective than sticky spheres, and wooden pesticide-treated spheres were least effective. Versions of pesticide-treated spheres used in 1999 were more durable than those used in previous years, but further improvement is needed before either wooden or sugar/flour pesticide-treated spheres can be recommended for grower use.     

Response of plum curculio (Coleoptera: Curculionidae) to odor-baited traps near woods.

Response of overwintered plum curculios, Conotrachelus nenuphar (Herbst), to odor-baited traps was evaluated from the beginning until nearly the end of emigration from overwintering sites in woods. We evaluated clear sticky Plexiglas panels and black pyramid traps placed close to woods adjacent to apple trees in an unsprayed section of an orchard. Traps were baited with aggregation pheromone (grandisoic acid) alone or in combination with one of six synthetic fruit volatiles (benzaldehvde, decyl aldehyde, E-2-hexenal, ethyl isovalerate, hexyl acetate, or limonene). Unbaited traps served as a control treatment. Plum curculio emigration from woods was divided into early-, mid-, and late-season periods based primarily on phenological stage of apple bud and fruit development (tight cluster to bloom, petal fall, and fruit set, respectively). During both early- and late season, panel and pyramid traps baited with benzaldehyde plus pheromone were significantly more attractive than any other traps (baited or unbaited), except panel traps baited with ethyl isovalerate plus pheromone in early season, which likewise captured significantly more adults than unbaited panel traps. During midseason, no lures were significantly attractive, possibly due to prevailing cool weather, unfavorable for adult activity. Over the entire season, panel or pyramid traps baited with benzaldehyde plus pheromone captured nearly six times as many plum curculios as unbaited traps of each type, whereas traps baited with pheromone alone captured about twice as many as unbaited traps of each type. We provide information on sex ratio, female maturity stage, and mating status, and several weather parameters associated with trap captures. We conclude that panel or pyramid traps, or a combination, baited with benzaldehyde plus pheromone placed at borders of plum curculio overwintering sites can be a valuable tool for monitoring the beginning, peak, and end of adult immigration into apple orchards.     

Movement of plum curculio adults toward host trees and traps: flight versus walking

Adult plum curculios, Conotrachelus nenuphar (Herbst), were dislodged from branches of apple trees by tapping on 14 days between blossom petal fall and 3 weeks thereafter. They fell onto a small square of framed white cloth that was quickly but carefully moved to a position beneath or adjacent to the canopy of another apple tree.There, adults were observed for 50-min periods from 0800–1950 h for propensity to fly from or walk off the cloth or move to hide beneath foliage on the cloth. At each position, the mean time from observation initiation until flight, walking off or hiding did not differ significantly among these behaviors (averaging 21–30 min), but significantly more flew (31–40%) than crawled off (16–19%) or hid (18–20%). Substantial walking off but no flights occurred at air temperatures below 20 °C, whereas at temperatures of 20 °C or greater, propensity for flight was usually significantly greater than that for walking off.Flights were predominantly toward the tree canopy or inter-tree space, with only a small proportion (17% or less) toward the tree trunk or (in a parallel study) toward an unbaited black pyramid trap (mimicking a tree trunk). Walking was overwhelmingly toward the tree trunk or a black pyramid trap adjacent to the trunk. Our observations lead us to conclude that unbaited black pyramid traps next to trunks of host trees (the most attractive position) can be effective at air temperatures below 20 °C by attracting plum curculio adults that would have entered host trees by walking toward and up tree trunks.Such traps appear to be less effective at 20 °C or greater because under such conditions, adults tend to enter host trees by flight into the canopy.     

An index for assigning distances between odor-baited spheres on perimeter trees of orchards for control of apple maggot flies

Previously, the distances between odor‐baited spheres deployed on perimeter trees of apple orchards for behavioral control of apple maggot flies, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), have been assigned largely arbitrarily. Here, we report a new approach for assigning distances that employs an index incorporating the state of four environmental variables: the size of orchard trees, quality of pruning, cultivar composition, and nature of bordering habitat. The deployment of odor‐baited spheres on the perimeters of 12 plots of apple trees (each ～0.4 ha) in commercial orchards in 2003 resulted in an apple maggot control which was no different from that achieved by insecticide sprays in adjacent plots in 2003, and no different from that achieved by an arbitrary assignment of distances between odor‐baited spheres on perimeter trees in these same plots in 2001 and 2002. However, only 61–67% of spheres were used under the new index approach compared with the previous arbitrary approach, thereby substantially reducing the cost of behavioral control. Our findings are discussed in relation to use of the index for blocks of trees which are large in size and pruned poorly vs. small in size and pruned well, and in relation to the cost‐competitiveness of odor‐baited perimeter spheres vs. insecticidal sprays for the control of apple maggots.     

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.     

Impact of temperature on plum curculio (Coleoptera: Curculionidae) responses to odor-baited traps

In 2005, captures of overwintered adult plum curculios, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in standard black masonite pyramid traps deployed in apple (Malus spp.) orchards from half-inch green until fruit reached 7 mm and baited with known attractants did not result in significant captures compared with unbaited traps as they had in 2003 and 2004. These baits included the synthetic aggregation pheromone, grandisoic acid (GA) alone, a six-component synthetic host plant volatile combination (6-Tree) identified from foliar and woody tissues of a Stanley plum tree in combination with GA (6-Tree+GA), and the synthetic fruit volatile benzaldehyde (BEN) in combination with GA (BEN+GA). In 2005, the average daily temperature was below 13 degrees C, much cooler than in 2003 and 2004. We hypothesized that plum curculio could not discriminate between baited and unbaited traps because of reduced release rates of odor-bait stimuli due to their temperature-driven release system. From data collected from 2003 to 2005, we found that plum curculio captures in traps baited with GA alone, 6-Tree+GA, and BEN+GA were significantly related to temperature. We created a predictive model to determine the level of activity, i.e., trap captures in baited traps compared with unbaited traps, we would expect to observe at a particular temperature for these same odor stimuli. Our models predicts that at temperatures between approximately 11 to 13 degrees C we would expect to see no difference between captures in baited and unbaited traps. For captures in odor-baited traps to reach twice those in unbaited traps, our model predicts that temperatures must reach 19.2 degrees C for GA alone, 18.5 degrees C for 6-Tree+GA, and 15.8 degrees C for BEN+GA.     

Incidence and control of dogwood borer (Lepidoptera: Sesiidae) and American plum borer (Lepidoptera: Pyralidae) infesting burrknots on clonal apple rootstocks in New York

Surveys were conducted in the major apple growing regions of New York state to determine the incidence of borers infesting burrknots on clonal apple rootstocks. Dogwood borer, Synanthedon scitula (Harris), was generally prevalent throughout the state, but American plum borer, Euzophera semifuneralis (Walker), was limited to western New York apple orchards near infested stone fruit trees. Insecticides evaluated in the field for efficacy against both borers were chlorpyrifos, endosulfan, indoxacarb plus oil, methoxyfenozide, fenpropathrin, and kaolin clay. Also, white latex paint was tested alone and mixed with chlorpyrifos. One application of chlorpyrifos applied at the petal fall developmental stage was equivalent to chlorpyrifos applied at petal fall and again in mid-July, and it provided season-long control of dogwood borer and American plum borer. One application of chlorpyrifos applied any time between the half-inch green developmental stage and petal fall, or after harvest the previous season, controlled both overwintered and summer brood larvae of dogwood borer. Multiple applications of fenpropathrin, indoxacarb plus oil, and endosulfan applied during the dogwood borer flight period controlled the summer brood.     

Phenology and infestation patterns of plum curculio (Coleoptera: Curculionidae) on four highbush blueberry cultivars

The plum curculio, Conotrachelus nenuphar (Herbst), is a well known pest in apple and peach orchards, but it also is capable of having an economic impact in highbush blueberries. Host phenology and plum curculio oviposition patterns were determined on four highbush blueberry cultivars differing in fruit maturation period. Numbers of oviposition scars were higher on early- ('Weymouth') and mid-season ('Duke' and 'Bluecrop') blueberries than on late-season 'Elliott' in 2001, 2002, and 2003. In 2002, eggs were first present on the three earliest cultivars 21 d before those on 'Elliott', whereas eggs were found on 'Elliott' >40 d after the last sample with eggs for the other three cultivars. The pattern of host phenology and infestation levels suggested that plum curculio oviposition synchronizes well with the availability of suitable fruit for oviposition on early and mid-season cultivars compared with a late-season cultivar of highbush blueberries. The implications of a transition to use of reduced-risk insecticides are discussed in relation to plum curculio management.     

Population dynamics of western flower thrips (Thysanoptera: Thripidae) in nectarine orchards in British Columbia

Development of a control strategy for thrips attacking nectarine trees depends on an understanding of their phenology, distribution, and life history as related to characteristics of nectarine orchards. To this end, we compared the overwintering behavior, distribution, and abundance of western flower thrips, Frankliniella occidentalis (Pergande), among 11 nectarine orchards located in the dry central interior of British Columbia, Canada, during 1993 and 1994. Western flower thrips emerged from areas not previously used for agriculture (wild areas) and from within orchards before trees were out of dormancy. Flight of thrips within and around orchards peaked during early bud development, with a second major peak several weeks later after husk fall as the next generation emerged. Orchards protected from wild areas by other orchards had the lowest densities of thrips in buds. Density estimates of western flower thrips on trees were not affected by location of trees within orchards or buds within trees, but most thrips were found in the most developed buds on a tree at any one time. Thrips were not found within buds until petal was first visible on the buds. Larval feeding on buds at early petal fall resulted in serious surface russetting of fruit.     

Evaluation of border sprays for managing the codling moth (Tortricidae: Lepidoptera) and the apple maggot (Tephritidae: Diptera) in Ontario apple orchards

The efficacy of two insecticide control programs for managing the codling moth, Cydia pomonella (L.), and the apple maggot, Rhagoletis pomonella (Walsh), were compared in the Georgian Bay, London, Niagara, and Quinte apple production areas of Ontario during 1995, 1996, and 1997. In the border spray program, an initial cover spray of organophosphorus insecticide was applied to eradicate codling moths that may have colonized a test plot during the previous growing season. Subsequent sprays were applied only to a four-tree-wide zone (approximately 20 wide) around the perimeter of the plot to control immigrating codling moths or apple maggots. In the cover spray program, all sprays of organophosphorus insecticide were applied to the entire plot. Apple maggot injury was significantly greater in border spray program plots than in cover spray program plots only during 1995 in the London production area. There was no significant difference in codling moth injury between border spray and cover spray plots in the four production areas during the three-year study. The elimination of cover sprays from border spray plots during July and August may have left the apple crop more susceptible to damage by second generation larvae of the obliquebanded leafroller, Choristoneura rosaceana (Harris), in the London production area during 1995. There was a trend of increasing codling moth injury from 1995 to 1997 in two border spray plots, and apple maggot injury was detected in these plots during the third year of the study.     

Susceptibility of fruit from diverse apple and crabapple germplasm to attack by plum curculio (Coleoptera: Curculionidae)

Plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), is an important apple, Malus domestica Borkh., pest that significantly hinders sustainable apple production in eastern North America. The potential for host plant resistance to plum curculio among apple germplasm has never been rigorously evaluated. Thus, studies were conducted to assess the susceptibility of a number of exotic and domestic Malus accessions housed at the USDA Plant Genetic Resources Unit (PGRU) "core" collection in Geneva, NY. Contrary to earlier published reports and promising data from a field assessment in 2005, these results suggest that there is probably little potential for genetic resistance to plum curculio among the Malus germplasm collection evaluated. More specifically, four Malus hybrid selections that have previously been released with claims of plum curculio resistance were shown to be susceptible to plum curculio attack. Because there are additional accessions housed at PGRU outside of the core collection that are currently classified as resistant, further studies are necessary to evaluate the true resistance qualities of these releases. It is also important to clarify such discrepancies in both the USDA online Germplasm Resources Information Network and in the horticultural literature. Although other Malus species exhibited some variability in fruit susceptibility, none could be classified as being truly resistant to plum curculio attack by any definition that would have relevance to commercial production and sale of apples.     

Effects of infestation with fruit tree red spider mite, Panonychus ulmi (Koch), on the growth and cropping of young fruit trees

When Brompton plum, and M. IV and Crab C apple rootstocks grown in pots were inoculated with fruit tree red spider mites (Panonychus ulmi (Koch)), shoot extension was decreased by 7–17%, the dry weight of the new shoot by 21–32%, and the dry weight increments of old stem and roots by 12–30%, and 7–50%, respectively, compared with control plants sprayed with the acaricide tetradifon. Some of these effects were found in a field experiment with Brompton plum, but not with potted M. I apple rootstocks. Infestation of fruiting Lord Lambourne apple trees, also in pots, had little effect on vegetative growth but in one experiment modified fruit setting, and decreased the dry-matter content, but increased the seed content of harvested fruit. Lighter inoculation caused no damage to Brompton plum. Spraying inoculated Brompton plum rootstocks with tetradifon + TEPP in mid-June and mid-July prevented damage, and though August sprays did not prevent damage to the new shoot, the decreases in dry weight increments of old stem and roots were only 9–13% and 11–19%, respectively, compared with 21–25% and 45–50% in infested, unsprayed plants.     

Evaluation of extended-season mating disruption of the Oriental fruit moth Grapholita molesta (Busck) (Lep., Tortricidae) in apples

Abstract:  Oriental fruit moth Grapholita molesta (Busck) (Lep., Tortricidae) has recently become a key pest of apples throughout the eastern USA. Pheromone-mediated mating disruption of Oriental fruit moth was successfully used in North Carolina apple orchards in the past few years. However, low levels of late-season fruit damage occurred in some orchards treated in late May with hand-applied pheromone dispensers because of inadequate dispenser longevity. To investigate alternative pheromone application schedules for extended mating disruption control, the following pheromone treatments were compared with conventional insecticides in Henderson County (NC) in 2002: late May application of hand-applied dispensers; late June application of hand-applied dispensers; late May application of hand-applied dispensers supplemented with a late August application of sprayable pheromone dispensers; late May application of hand-applied dispensers which have a longer activity period; and conventional insecticides as a control. All treatments were sprayed with an insecticide at petal fall in late April for thinning and for control of the first generation Oriental fruit moth adults. Pheromone trap catches were significantly reduced in all mating disruption blocks compared with conventional insecticide blocks. Among pheromone treatments, the highest trap captures were recorded in the delayed hand-applied dispenser treatment in June before treatment. However, the mean percentage fruit damage did not vary with timing of application of hand-applied dispensers and the type of pheromone dispenser used. Clearly, the combination of each mating disruption treatment with insecticide application against first generation Oriental fruit moth was as effective as the conventional insecticide treatment under moderate population pressure.     

The efficacy of an improved form of the mass-trapping method, forthe control of the olive fruit fly, Bactrocera oleae (Gmelin) (Dipt., Tephritidae): pilot-scale feasibility studies

Abstract:  The efficacy of an improved form of the mass-trapping method for the control of the olive fruit fly, Bactrocera oleae (Gmelin) was tested for 4 years in a pilot test at Tanagra Voeotia, Greece. Improvements consisted of the extension of the active life of the toxic trap used, active life referring both to its attracting and killing properties, as well as in trap deployment, which combined efficacy and low cost. The method was compared to bait sprays applied from the ground, which constitutes the current standard method for the control of this pest. Both pest population density and fruit infestation levels, the main parameters used for the evaluation of the two methods were considerably lower during all 4 years of tests in the orchards protected by mass trapping compared with those in the orchards protected by bait sprays. Furthermore no complementary measures were required in the mass-trapping orchards for acceptable crop protection, which was not the case under certain conditions, prior to the introduction of the recent improvements. The cost of the mass-trapping method was approximately US$ 0.40 per tree per year compared with US$ 0.35 for bait sprays (figures of the Greek Ministry of Agriculture). However, the mass-trapping method reduces the amount of insecticide used for olive protection by 99.5% (15 mg a.i. per tree per year as opposed to 3 g in the case of bait sprays). A considerable reduction in the cost of the mass-trapping method is expected with the extension of its use and the mass production of materials used, especially traps.