Pheromone-treated Plots Research Articles

Field effectiveness of Metarhizium anisopliae and pheromone traps against Phthorimaea absoluta on tomato in Tanzania

Phthorimaea absoluta is an invasive pest and a major threat to tomato production in sub-Saharan Africa, including Tanzania. Although chemical pesticides are commercially available and used locally, mis- and overuse can cause detrimental effects on human and environmental health, and can lead to emergence of resistance among populations of P. absoluta within a short period, increasing production costs among smallholder farmers in Tanzania. The effectiveness of alternative options, such as the use of biological control agents and pheromone traps, has not yet been studied in the field in sub-Saharan Africa. The present study evaluated the effectiveness of a commercially available biopesticide based on Metarhizium anisopliae and pheromone traps for managing P. absoluta in field conditions in Tanzania during the dry and wet season, and compared effectiveness with chemical pesticides (a combination of chlorantraniliprole, emamectin benzoate, spinetram and flubendiamide) and untreated plants as a positive and negative control, respectively. The two field experiments were conducted in a randomized complete block design with three replications per treatment. Two weeks after transplanting, 20 plants were randomly selected from each plot, with the number of fully expanded leaves per plant and mines per plant counted at 7-day intervals until harvest. At harvest, the number and weight of damaged and marketable fruits were recorded, and yield and marketable yield per plot calculated. The number of leaves per plant (an indicator of P. absoluta infestation) was higher in the wet season than in the dry season. In the wet season, M. anisopliae-treated plants contained more leaves than plants in control or pheromone-treated plots. The number of P. absoluta mines per plant was higher in the dry season than in the wet season. In the dry season, the number of mines per plant was higher in control plots than in plots of other treatments. However, total yield and marketable yield were higher during the dry season than during the wet season. During both seasons, damage was highest and yield lowest in control plots. During the dry season, total yield and marketable yield did not differ significantly between pesticide-treated and M. anisopliae-treated plots. Biological control using M. anisopliae could be integrated in field management of P. absoluta in tomato in the highlands of Tanzania as well as in other regions of this country and throughout Africa.

Field tests of candidate pheromone blends show promise for mating disruption of the invasive swede midge (Diptera: Cecidomyiidae)

Abstract Swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), causes severe economic losses in Brassica Linnaeus (Brassicaceae) crops in its invasive range in North America. Larvae feed within the meristem of their host plants, causing deformed heads, stems, and leaves. Pheromone-mediated mating disruption is particularly promising for swede midge management in high-value vegetable crops because its use is allowed in organic production. However, a major challenge to developing economically viable mating disruption is that the stereospecific three-component swede midge pheromone is costly to synthesise. In broccoli (Brassica oleracea Linnaeus var. italica) field plots, we tested whether stereospecific, lower-cost racemic, and single-component pheromone blends resulted in trap shutdown and reduced crop damage compared to nontreated controls. We found a significant reduction in males caught in three-component stereospecific and racemic pheromone–treated plots but not in the single-component treatments. Although marketable broccoli yields were not higher overall in the pheromone-treated plots compared with those in the controls, yields were significantly higher in the three-component stereospecific treatment in year 2. Therefore, the three-component stereospecific blend shows promise as a pheromone blend for swede midge mating disruption. However, due to high cost and levels of crop damage across all treatments, additional research is necessary to optimise swede midge mating disruption.

Synthetic pheromone exposure increases calling and reduces subsequent mating in female Contarinia nasturtii (Diptera: Cecidomyiidae).

Pheromone-mediated mating disruption, which uses large amounts of synthetic female pheromones to interrupt insect reproductive behavior, has been successful for managing important agricultural pests. While multiple mechanisms have been discovered explaining how synthetic pheromone treatments prevent males from finding females, it is less clear how unnaturally large doses of synthetic sex pheromone impact the behavior of female insects, particularly nonlepidopteran females. In some species, 'autodetecting' females possess pheromone receptors and respond to ambient pheromones by altering their mating behavior. Here, we test whether exposure to stereospecific and racemic synthetic pheromones influences calling and subsequent propensity to mate in female swede midge (Contarinia nasturtii Kieffer; Diptera: Cecidomyiidae), a pest of Brassica crops. In both laboratory and field settings, females exposed to stereospecific and racemic three-component pheromone blends called significantly more frequently and for longer durations than midges in control treatments. In the field, midges were twice as likely to call in pheromone-treated plots versus nontreated plots. Additionally, pheromone pre-exposure reduced subsequent mating: while 68% of female midges mated following control conditions, only 42% and 35% of females pre-exposed to stereospecific and racemic three-component blends mated, respectively. While more frequent calling within pheromone-treated backgrounds may increase the likelihood that females are detected by males, a reduction in female propensity to mate would increase the efficacy of a pheromone-mediated mating disruption system. Our work presents the first known investigation of autodetection behavior in Cecidomyiidae. Additional research is necessary to understand the implications of female autodetection for swede midge management.

Challenges of pheromone-based mating disruption of Cydia strobilella and Dioryctria abietella in spruce seed orchards

Seed orchards function as the primary source of high-quality seeds for reforestation in many European countries, but their seed yields can be severely reduced due to seed- and cone-feeding insects. We evaluated various parameters of pheromone-based mating disruption for control of the moths Cydia strobilella and Dioryctria abietella, which are major pests in European Picea abies seed orchards. We applied different types of pheromone dispensers (rubber septa or wax droplets) at different densities and heights, and with different amounts of active components, covering whole orchards or part of an orchard. The efficacy of the treatment was evaluated by analysing male captures in pheromone-baited assessment traps, and presence of larvae in cones. A dramatic decrease (94–100%) in capture of males in traps occurred in all pheromone-treated plots compared to control plots for both moth species. In contrast, a subsequent reduction in larval numbers in cones was only achieved when wax droplets were used as the dispensing formulation at high density and at the highest pheromone dose tested, and only in half of the trials for each pest species. Electrophysiological recordings using antennae of male C. strobilella indicated elevated pheromone concentrations in a treated plot versus a control plot. Our results show that mating disruption has potential to reduce cone damage in spruce seed orchards caused by C. strobilella and D. abietella, but optimisation of the technique is required to achieve consistent and efficient population suppression of these pests.

First Report of Mating Disruption With an Aggregation Pheromone: A Case Study With Tetropium fuscum (Coleoptera: Cerambycidae).

Tetropium fuscum (F.), native to Europe and established in Nova Scotia, Canada, since at least 1990, is considered a low-to-moderate threat to spruce (Picea spp.) forests in North America and regulated as a quarantine pest by the Canadian Food Inspection Agency. We tested broadcast applications of the aggregation pheromone racemic (5E)-6,10-dimethyl-5,9-undecadien-2-ol (fuscumol), formulated at 10% concentration in Hercon Bio-Flakes (Hercon International, Emigsville, PA), for efficacy in disrupting T. fuscum mating and suppressing populations. Two applications of 2.5-2.75 kg Bio-Flakes (250-275 g a.i.) per ha per season significantly reduced trap catches and mating success (2009, 2010, 2012): about 30% of females trapped in treated plots had mated compared with 60% of females trapped in untreated plots. Similar reductions in mating success were observed in 2011 with one or two 4.5 kg/ha applications of Bio-Flakes. Mean densities of T. fuscum colonizing sentinel bait logs or girdled trees were 36% lower in pheromone-treated plots than in untreated plots, but the difference was not statistically significant. Lack of population suppression may have been because mated females immigrated into treated plots or because populations were so high that despite a 50% reduction in mating success, absolute numbers of mated females were sufficient to infest our bait logs or trees. This is the first demonstration of insect mating disruption via broadcast application of an aggregation pheromone. Pheromone-mediated mating disruption has potential to slow the spread of invasive cerambycids by targeting low-density outlier populations near or beyond the leading edge of an infestation.

The Long-Term Effects of Reduced Competitive Ability on Foraging Success of an Invasive Pest Species

Ant species like Pheidole megacephala (F.), Solenopsis invicta (Buren), and the Argentine ant, Linepithema humile (Mayr), have repeatedly been reported to be strongly associated with honeydew-producing arthropods like aphids, scale insects, and mealybugs, effectively protecting them from biological control agents like parasitoids. Here we report the results of a successful trial using pheromone dispensers to suppress Argentine ant activity over large sections in a commercial vineyard over a period of two months and preventing ant access into and foraging within the vine canopy. We found Argentine ant activity to be significantly reduced in pheromone-treated plots for the duration of the trial period compared with control plots. Our results showed a significant reduction in the numbers of Argentine ant workers recruited to randomly placed food resources within treated plots compared with untreated plots. Furthermore, spatial distribution of Argentine ants alongside transects in untreated plots remained relatively continuous, while increasing sharply beyond the borders of treated plots. Lastly, we measured the body fat content of workers and found a significant reduction in fat among workers from treated plots compared with untreated plots, suggesting an adverse effects on nest fitness. Additionally, we provide an initial assessment of the feasibility of the presented approach. Our results showed that it is possible to control Argentine ant, preventing them access to and foraging within the vine canopy, thereby reducing Argentine ants' access to honeydew.

Challenges of Mating Disruption Using Aerosol-Emitting Pheromone Puffers in Red Clover Seed Production Fields to Control Coleophora deauratella (Lepidoptera: Coleophoridae).

Sex pheromone-mediated mating disruption using pheromone puffer dispensers was evaluated to control Coleophora deauratella (Lepidoptera: Coleophoridae) at three red clover seed production fields in Alberta, Canada. The objectives of the study were to determine aspects of the biology of C. deauratella which may affect successful mating disruption, evaluate the ability of aerosol-emitting pheromone puffers to reduce male moth catch in small-plot trials, and evaluate the ability of puffers to reduce male capture in traps, larval numbers and damage in large-plot trials. The median longevity of male and female C. deauratella was 6 d in the laboratory where males emerged in larger numbers earlier than females (protandry). Male response to pheromone peaked at sunrise; thus, puffers were programmed to dispense pheromone throughout this time period. Small-plot (0.25 ha) mating disruption trials indicated that pheromone released from puffers could reduce male C. deauratella orientation to traps by 60.7 ± 18.6% compared with that in untreated control plots. Reduction of male orientation to traps in large-plot (5 ha) trials over the course of the season was also successful (93.7 ± 1.6%). However, there was no corresponding decrease in larval numbers or increase in seed yield in pheromone-treated plots. Challenges of mating disruption of C. deauratella appear to be immigration of mated females combined with high population densities.

Mating disruption of Coleophora deauratella (Lepidoptera: Coleophoridae) using laminate flakes in red clover seed production fields.

The red clover casebearer, Coleophora deauratella, is a significant pest in red clover (Trifolium pratense) seed production regions throughout the world. The internal feeding nature of C. deauratella larvae makes infestations difficult to control with insecticide. We test the ability of Hercon Disrupt Micro-Flakes(®) releasing the complete pheromone blend of C. deauratella to disrupt communication and mating in red clover seed production fields. Initial small-plot (0.25 ha) trials found a significant reduction (93.6 ± 2.9%) of male C. deauratella captured in pheromone-treated plots compared with untreated controls. Subsequent large-plot (5 ha) mating disruption trials found a significant reduction (72.3 ± 5.7%) in male C. deauratella captured in pheromone-treated plots compared with untreated control plots over the growing season. Furthermore, larval numbers were significantly reduced and seed yield was increased in pheromone-treated plots compared with untreated control plots. In a concurrent small-plot (0.0625 ha) trial with various flake densities, disruption increased with pheromone flake density, and the resulting graphical disruption profiles matched the theoretical predictions of mating disruption by competitive attraction. Pheromone-mediated mating disruption with laminate flakes has the potential to suppress C. deauratella populations and may help to reduce damage even at high pest densities. © 2014 Society of Chemical Industry.

Efficacy and mechanisms of communication disruption of the red clover casebearer moth (Coleophora deauratella) with complete and partial pheromone formulations.

The red clover casebearer, Coleophora deauratella Leinig and Zeller (Lepidoptera: Coleophoridae), is a major pest of red clover (Trifolium pratense L.) grown for seed in Canada and parts of Europe. Insecticides are ineffective against C. deauratella, and other control methods, such as pheromone-mediated mating disruption, need to be explored. The efficacy and mechanisms of communication disruption were evaluated in small-plot trials (0.25 ha) with reservoir-type rope dispensers loaded with either the complete pheromone blend [10:1 ratio of (Z)-7-dodecenyl acetate: (Z)-5-dodecenyl acetate] or the major component alone [(Z)-7-dodecenyl acetate]. Both formulations reduced catches of male C. deauratella in pheromone traps (>99.6 %). In pheromone-treated plots, more males were caught on yellow sticky cards near dispensers that released the complete pheromone blend, than on cards near dispensers releasing the major component. In the laboratory, after pre-exposure to either the complete blend or the major component for 1 h, male C. deauratella antennae became adapted, as measured by electroantennograms conducted 5 min. after treatment. Adaptation due to pre-exposure to either formulation resulted in a shift in the pheromone response threshold; antennae from pre-exposed moths responded more strongly to high pheromone dosages (5-50 μg) than did antennae from untreated control moths. Antennae from moths held in clean air for 24 h after pre-exposure recovered and responded similarly to pheromone as antennae from control moths. These results suggest that both formulations have the potential to disrupt pheromone communication in C. Deauratella, but that the disruption mechanisms of the two formulations likely differ.

C. P. Alexander review

AbstractThe Canadian registration in 2007 of Disrupt SBW Micro-Flakes®, a pheromone-based product for control of spruce budworm,Choristoneura fumiferana(Clemens), paved the way for large-scale trials to test the practicality of mating disruption as a commercial pest management strategy. We review results from field and laboratory experiments on pheromone-based mating disruption of spruce budworm conducted from 1974 to 2008. Application of pheromone from the ground or the air consistently reduced the orientation of males toward pheromone sources. Mating disruption also reduced the mating success of caged or tethered females in 15 of 16 field studies where this parameter was recorded, but had only a limited effect on the mating success of feral females. No consistent difference in the density of egg masses in control and treated plots was observed, which has often been attributed to immigration of gravid females into pheromone-treated plots. Laboratory studies suggest that false-trail following is the predominant mechanism underlying mating disruption in spruce budworm. The enhanced mating success of females with increasing population density suggests that mating disruption should target low-density emergent populations during the initial phase of an outbreak. Constraints that may limit the potential of mating disruption as a management tool include (1) difficulties associated with obtaining accurate sampling estimates at low population density to forecast the onset of outbreaks, (2) potential behavioral adaptations by which females enhance their mating success when the atmosphere is treated with pheromone, and (3) long-range dispersal of females by flight.

MATING DISRUPTION OF CODLING MOTH, CYDIA POMONELLA L., BY APPLICATIONS OF THE MICROENCAPSULATED FORMULATION CHECKMATE® CM-F IN BULGARIA

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Organic Horticulture: Productivity and Sustainability MATING DISRUPTION OF CODLING MOTH, CYDIA POMONELLA L., BY APPLICATIONS OF THE MICROENCAPSULATED FORMULATION CHECKMATE® CM-F IN BULGARIA

SPLAT-OrB Reveals Competitive Attraction as a Mechanism of Mating Disruption in Oriental Beetle (Coleoptera: Scarabaeidae)

This study compared the efficacy of SPLAT-OrB, a new pheromone formulation for oriental beetle mating disruption that can be mechanically applied, with hand-applied plastic dispensers in commercial blueberry fields. Both formulations were tested at 2.5 and 5 g of the major sex pheromone component (Z)-7-tetradecen-2-one per hectare, and evaluated by measuring trap shut-down, mating success of caged females, and the number of grubs in sentinel blueberry pots baited with tethered females. All pheromone-treated plots had fewer male captures in traps and lower mating success of caged females compared with untreated plots. SPLAT-OrB, and plastic dispensers at the higher rate, also reduced the number of grubs in sentinel pots. To understand the mechanism of mating disruption in oriental beetle, males were observed approaching the pheromone sources in disrupted plots. In addition, male oriental beetle captures were quantified in plots treated with varying SPLAT-OrB dollop densities per ha. Consistent with predictions for competitive attraction, field observations revealed males approaching the pheromone source and male captures decreasing concavely with increasing dollop density. In a mark-release-recapture study, male oriental beetles responded to SPLAT-OrB dollops and plastic dispensers at least 60 m from the source. Additionally, SPLAT-OrB emitted pheromone that was attractive to male oriental beetles for >5 wk; however, emission rates and attraction dropped rapidly during the first 3-4 wk. This study demonstrates the feasibility of using SPLAT-OrB for oriental beetle mating disruption as an alternative to hand-applied plastic dispensers, and conclusively reveals that a principal mechanism is the competitive attraction of males.

Suppression of Leopard Moth (Lepidoptera: Cossidae) Populations in Olive Trees in Egypt Through Mating Disruption

The leopard moth, Zeuzera pyrina (L.) (Lepidoptera: Cossidae), is a damaging pest for many fruit trees (e.g., apple [Malus spp.], pear [Pyrus spp.] peach [Prunus spp.], and olive [Olea]). Recently, it caused serious yield losses in newly established olive orchards in Egypt, including the death of young trees. Chemical and biological control have shown limited efficiency against this pest. Field tests were conducted in 2005 and 2006 to evaluate mating disruption (MD) for the control of the leopard moth, on heavily infested, densely planted olive plots (336 trees per ha). The binary blend of the pheromone components (E,Z)-2,13-octadecenyl acetate and (E,Z)-3,13-octadecenyl acetate (95:5) was dispensed from polyethylene vials. Efficacy was measured considering reduction of catches in pheromone traps, reduction of active galleries of leopard moth per tree and fruit yield in the pheromone-treated plots (MD) compared with control plots (CO). Male captures in MD plots were reduced by 89.3% in 2005 and 82.9% in 2006, during a trapping period of 14 and 13 wk, respectively. Application of MD over two consecutive years progressively reduced the number of active galleries per tree in the third year where no sex pheromone was applied. In all years, larval galleries outnumbered moth captures. Fruit yield from trees where sex pheromone had been applied in 2005 and 2006 increased significantly in 2006 (98.8 +/- 2.9 kg per tree) and 2007 (23 +/- 1.3 kg per tree) compared with control ones (61.0 +/- 3.9 and 10.0 +/- 0.6 kg per tree, respectively). Mating disruption shows promising for suppressing leopard moth infestation in olives.

Evaluation of aerosol devices for simultaneous disruption of sex pheromone communication in Cydia pomonella and Grapholita molesta (Lepidoptera: Tortricidae)

A two-year study was conducted evaluating Puffer® aerosol dispensers (Suterra LLC, Bend, OR, USA) for mating disruption of codling moth, Cydia pomonella (L.), and the oriental fruit moth, Grapholita molesta (Busck). The Puffer® dispenser consists of a pressurized metal canister loaded with pheromone active ingredients dissolved in solvent and housed within a circuit-controlled, plastic dispensing cabinet programmed to release an aerosol spray of pheromone at regular intervals. Puffers® were deployed at the label-recommended rate of 2.5 ha−1 and released ca. 5–10 mg of pheromone (depending on treatment) per 15 min during a 12-h cycle beginning each day at 15:00 h for the duration of the season. In 2005, commercially-managed apple plots (3.2–4.9 ha) were treated with Puffers® releasing both species’ pheromone simultaneously (dual-species) or with twice the number of adjacently-deployed Puffers® (4–6 m apart) releasing each individual species’ pheromones (single-species), while maintaining comparable overall release rates of pheromone between these two treatments. Plots 100 m away and not treated with pheromone served as the control. Disruption of male C. pomonella and G. molesta orientation to pheromone-baited traps was 46–75 and 91–98%, respectively, in Puffer®-treated plots compared with untreated controls. There was no statistical difference in moth disruption between plots treated with dual-species and single-species Puffers®. Fruit injury was not statistically different between Puffer®-treated plots and control plots not receiving pheromone. In 2006, disruption of male moth orientation to traps was 24–26 and 84–97% in Puffer®-treated plots (2.9–5.7 ha) for C. pomonella and G. molesta, respectively, compared with untreated controls. During this season, fruit injury was lower in pheromone-treated plots compared with untreated controls at mid-season, but not at pre-harvest. Combining the pheromone of both species into single Puffer® units did not decrease efficacy of disruption compared with deploying twice as many Puffers® releasing a similar amount of each individual species’ pheromone suggesting that multi-species disruption using Puffers® is a viable option. However, we conclude that the efficacy of disruption attained with low-densities (2.5 ha−1) of Puffers® at the moth densities recorded in this study is insufficient for effective control of C. pomonella without input of companion insecticides.

Pest management programmes in vineyards using male mating disruption

Israeli vine growers have been reluctant to adopt the mating disruption technique for control of the European vine moth, Lobesia botrana Den. & Schiff. Since the chemically controlled honeydew moth, Cryptoblabes gnidiella Mill., coexists with the European vine moth, growers have maintained that the use of mating disruption would fail to bring about a significant reduction in pesticide use. In this study, the efficacy of mating disruption techniques against C. gnidiella was tested, as well as the effect of these methods on pesticide use and damage to clusters when the method was employed against both of the pests in wine grapes. Comparisons were made between plots treated with (1) L. botrana mating disruption pheromone, (2) L. botrana and C. gnidiella mating disruption pheromones and (3) control plots. A significant difference in the number of clusters infested with the developmental stages of the moths was seen between pheromone-treated plots and controls, while no such difference was observed between plots treated with one versus two pheromones. A similar pattern was observed in the number of insecticide applications; the greatest number of applications was used in control plots, followed by plots treated with L. botrana mating disruption pheromone and by plots treated with pheromones against both pests, in which no pesticides were applied.

Mating Disruption of Oriental Beetle (Coleoptera: Scarabaeidae) in Cranberry Using Retrievable, Point-Source Dispensers of Sex Pheromone

We evaluated the potential management of oriental beetle, Anomala orientalis (Waterhouse), in cranberry by disruption of communication between the sexes through application of the female sex pheromone deployed from wax disks in 2003 and 2004. Mean weekly catch of males in pheromone traps on each untreated bog minus that on each pheromone-treated bog was significantly greater than zero throughout the male flight period for both years of the experiment. Captures of males in traps placed on the edge of pheromone-treated bogs were intermediate between those on control and treated sites; thus, disruption may be limited a short distance from pheromone-treated plots, and treatment of surrounding areas that harbor beetles may be necessary. We deployed a limited number of tethered virgin females in the field for two nights in 2003; when returned to the laboratory, only females on control sites laid fertile eggs. In 2004, we assessed whether delayed mating occurred in the field by deploying tethered females within soil-filled pots and estimated mating rates over five nights by the presence or absence of fertile eggs within soil samples. Only one female among the treated sites laid fertile eggs, whereas the cumulative percentage of females laying fertile eggs in control sites rose steadily over five nights to 96%. The results of this study suggest the strong potential of mating disruption of oriental beetle in cranberry using retrievable, high-dose, point-source dispensers of pheromone.

Potential for use of synthetic sex pheromone for mating disruption of the olive pyralid moth, Euzophera pinguis.

The potential for pheromone-based mating disruption of the olive pyralid moth (OPM), Euzophera pinguis, in olive groves was investigated during the second flight period in small-plot trials in 2002. The female of this species emits a blend of (9Z,12E)-tetradecadien-1-ol and (9Z,12E)-tetradecadienyl acetate, which were synthesized for field tests. Mating disruption efficacy in 0.8-ha trials was evaluated using two parameters: reduction of male capture in pheromone traps and reduction of infestation in infestation-prone sites. White rubber septa containing 10 mg of pheromone blend as disruptant were applied at a density of 50 septa/ha for each treatment. Mean catches of E. pinguis males in pheromone traps were greatly reduced (> 95%) in pheromone-treated plots relative to similar traps placed in control plots. In addition, significant reductions were recorded (35-40%) in the oviposition and infestation levels during pheromone treatment. The total amount of pheromone blend released from disruption dispensers during the field trials was estimated to average 5.4 mg/ha/day, over 56 days.

SPODOPTERA EXIGUA : MATING DISRUPTION, MEASUREMENT OF AIRBORNE CONCENTRATION OF PHEROMONE, AND USE OF SPECIALIST RECEPTOR CELL RESPONSES FOR COMPARISON TO FEMALE PHEROMONE EMISSION

Field experiments were conducted to evaluate Shin-Etsu Yoto-con-S® ‘rope’ pheromone dispensers applied at different site densities in cotton to determine effficacy in disrupting sexual communication and mating of beet armyworm moths, Spodoptera exigua (Hübner); obtain atmospheric measurements of the disruptant pheromone components in and away from treated areas; and relate this information to estimates of the concentration of pheromone in the near vicinity of a calling virgin female moth. The number of pheromone-dispensing sites/ha ranged from 25 with 20 ropes/site up to a total of 247 sites with 2 ropes each. A total of 112 g pheromone of a 70:30 blend of (Z,E)-9,12-tetradecadien-1- ol acetate (ZETA) and(Z)-tetradecen-1-ol (Z9–14:OH) was applied/ ha. As few as 25 sites/ha effectively disrupted sexual communication by 91%, as measured by reductions of moth captures in traps baited with pheromone lures, and mating by beet armyworm females by 94% for at least 10 weeks post-treatment. The results compared favorably to an earlier large-scale field experiment in which beet armyworm larval populations were reduced 95% using 500 pheromone-dispensing sites/ha (two ropes/site) and 160 g total pheromone/ha. The airborne concentration of ZETA and Z9–14:OH measured within the pheromone-treated plots that disrupted mating was 1.5 × 1013 M and 1.2 × 1013 M, respectively. The airborne concentration of ZETA and Z9–14:OH in the vicinity of a female was estimated (by excision and electrophysiological methods) to range between 2.1 × 1011 M and 2.4 × 1012 M, respectively, in a 1.6 km / h (1 mph) wind speed. Thus, the average ZETA concentration in the treated plots was about 140 times less than that expected from a single female; the average Z9–14:OH in the treated plots was about 20 times less. The data support an argument that disruption of mating by beet armyworm resulted from an imbalance in sensory input because mating was almost completely disrupted in all of the plots for at least 10 weeks with a mixture of ZETA:Z9–14:OH that differed significantly with that from excised female sex pheromone glands. Estimates of these parameters provide a benchmark for the requisite pheromone concentration in the atmosphere to achieve a high level of mating disruption for beet armyworm and possibly other insect pest species.

DISRUPTION OF MATING IN THE SPOTTED TENTIFORM LEAFMINER (LEPIDOPTERA: GRACILLARIIDAE) USING SYNTHETIC SEX PHEROMONE

AbstractThe potential for using synthetic sex pheromone to disrupt mating of spotted tentiform leafminers, Phyllonorycter blancardella (F.), was evaluated in four experimental and two commercial apple, Malus domestica (Borkh) (Rosaceae), orchards in Ontario during 1992 and 1993. The average disruption index [i.e., (total number of moths trapped in control plot – total number of moths trapped in pheromone-treated plot)/total number of moths trapped in control plot × 100] was 80.7% when leafminer pheromone, (E)-10-dodecen-1-yl-acetate, was evaporated into square, approximately 400-m2 plots. During the 2-year study, pheromone was evaporated into the pheromone-treated plots at an average hourly rate of 39.6 mg/ha. There was no relationship between the estimated release rate of pheromone and average temperature. There was a negative linear relationship between the disruption index and leafminer density, as measured by the number of moths trapped in the control plot. There was no relationship between the disruption index and the estimated release rate of pheromone. Our results suggest that it may be possible to control the spotted tentiform leafminer using sex-pheromone-mediated mating disruption.

Effect of density of pheromone sources, pheromone dosage and population pressure on mating of pink bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae)

AbstractThe effect of density of the Shin-Etsu twist-tie rope pheromone formulation (PBW rope L®) on mating of female pink bollworm, Pectinophora gossypiella(Saunders) was tested in Israel. The success of mating disruption was evaluated during 1997 by the mating table technique, comparing the percentage of mating of virgin sentinel females in pheromone-treated and control plots. Under low pest population pressure application of ‘long-life’ formulation of P. gossypiellapheromone, PBW rope L®, spaced 9 m, 11 m and 14 m apart, resulted in very high suppression of mating (96.5–100%) and complete shut-down of pheromone trap catch. These application rates were much lower than those now prevailing in Israel and elsewhere. Spacing of ropes 20 m apart resulted in less effective mating disruption of 65% only, and shut-down of pheromone traps was also incomplete. The tests during 1998 were carried out at high pest population and efficacy of treatments was assessed by the reduction of male capture in traps in pheromone-treated plots relative to catches in the control. The distance between pheromone sources proved to be the most critical factor determining success. In both years, any spacing significantly greater than 10 m gave markedly less than complete trap catch shutdown/mating suppression. Pheromone dosages and population density were also important in determining mating success. Results obtained in this study indicate the possibility of reducing the number of pheromone sources per unit area and the total amount of pheromone as compared with that in use today, only at very low pest populations. However at high population levels, dispensers closely-spaced, with increased dosages of pheromone, are required.