Attractiveness of year-old polyethylene Isonet sex pheromone dispensers for Lobesia botrana

In this study, we have compared the release of sex pheromone from mating disruption dispensers exposed in the field for 12 months and from calling females. The main pheromone component of the grapevine moth, Lobesia botrana (D. and S.) (Lepidoptera: Tortricidae), is (E)‐7,(Z)‐9‐dodecadienyl acetate, and a minor component is (Z)‐9‐dodecenyl acetate. Aged dispensers from two different years emitted a much higher amount of both pheromone components than calling females. However, the summer temperature during field exposure influenced the release from mating disruption dispensers the following year. In the wind tunnel, male L. botrana were equally attracted to 12‐month, field‐exposed dispensers, a standard monitoring pheromone lure, and to synthetic (E)‐7,(Z)‐9‐dodecadienyl acetate sprayed at the rate of 0.6–60 ng h^?1. Field trapping tests confirmed that aged dispensers from both years were at least as attractive to L. botrana males as a standard monitoring pheromone lure. The possible contribution of previously applied dispensers to the mating disruption efficacy during following applications is discussed.     

The sublethal effects of tebufenozide on the precopulatory and copulatory activities of Choristoneura fumiferana and C. rosaceana

The sublethal effects of tebufenozide, an ecdysone agonist, on the reproductive biology of Choristoneura fumiferana (Clem) and of Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), treated during the larval stage, were evaluated using two treatment methods: the force‐feeding method and the diet method. The percentage of mortality and the developmental time of survivors increased linearly with the concentration of tebufenozide used. This ecdysone analogue proved to be more toxic to C. fumiferana than to C. rosaceana. In C. rosaceana, the weight of males and females decreased proportionally with the dose ingested, but females were affected to a greater extent. This difference might be due to a greater consumption of the treated diet, or to a differential vulnerability to tebufenozide. Tebufenozide did not modify the pre‐copulatory activities associated with chemical communication in the females. However, the consumption of tebufenozide delayed ovarian maturation, causing a reduction in the fecundity of females. Treated males had smaller spermatophores and fewer eupyrene sperms in their bursa copulatrix and spermatheca, along with lower mating success. In C. fumiferana, tebufenozide delayed the females’ onset time of calling the first night after emergence, but did not affect the mean time spent calling or the production of the main component of the sex pheromone. The males showed significantly greater difficulty in executing oriented flight in a wind tunnel, although their mating success was not affected. We concluded that tebufenozide interferes with various aspects of the reproductive biology of males and females of C. fumiferana and C. rosaceana, including some pre‐copulatory behaviors associated with sex pheromone communication.     

Investigations of Mechanisms of Pheromone Communication Disruption of Choristoneura rosaceana (Harris) in a Wind Tunnel

Although atmospheric treatment with synthetic pheromone is used commercially to control several lepidopteran pests, little is known about how mate-finding behavior is altered by this procedure. Mechanisms of disruption of the mate-finding behavior of Choristoneura rosaceana (Lepidoptera: Tortricidae) were examined in wind tunnel bioassays. Male moths were exposed to synthetic sex pheromone or pheromone components prior to or during upwind flight to a calling virgin female. The proportion of males successfully contacting a calling female was reduced only when the synthetic pheromone treatment was presented simultaneously. A synthetic source of the attractive four-component pheromone placed upwind of a calling female was more effective than a less attractive two-component blend in achieving disorientation. Habituation of the central nervous system does not appear to be a significant factor in disruption of mate-finding behavior of male C. rosaceana, as exposure to pheromone prior to the bioassay did not alter the proportion of males that achieved subsequent upwind flight. Disruption of mate-finding behavior of C. rosaceana in a wind tunnel is probably the result of a combination of mechanisms including adaptation of antennal receptors, camouflage of the female-produced plume, and false-trail following which contributed to the additive disruption effect observed with the most attractive four-component pheromone.     

Sex pheromone production and perception in the mating disruption-resistant strain of the smaller tea leafroller moth, Adoxophyes honmai

Mating disruption is an environmentally safe plant protection strategy that uses a synthetic copy of an insect pheromone to interfere with sexual communication and hence reproduction. To date, a number of pest moths have been controlled with applications of formulated pheromones as mating disruptants. Recently, however, the first example of resistance to mating disruption was documented in one of the major tea pests in Japan, the smaller tea leafroller moth, Adoxophyes honmai Yasuda (Lepidoptera: Tortricidae). To avoid other such cases, it is important to elucidate the mechanism(s) by which the disruptant lost its effectiveness. To this end, we imposed further selection by rearing field‐collected resistant insects with a synthetic pheromone in the laboratory. After more than 70 generations of selection, a strain with quite strong resistance was established, males of which could find and copulate with their mates even in the presence of 1 mg l^?1 of disruptant. Although the mating ability of this strain was greatly increased, the composition and blend ratio of the sex pheromone produced and emitted by females were not obviously changed in comparison with those of females sensitive to mating disruption. However, male response to the pheromone blend was markedly broadened after selection so that resistant males could locate a synthetic pheromone source even when it lacked a pheromone component that is normally necessary for attraction. Males capable of locking onto off‐ratio pheromone blends may be better able to find calling females in pheromone‐treated environments than narrowly tuned males because of greater capability of overcoming sensory imbalance.     

Concentration of air-borne pheromone required for long-lasting peripheral adaptation in the obliquebanded leafroller, Choristoneura rosaceana

Abstract. Electroantennogram (EAG) responses of male obliquebanded leafrollers, Choristoneura rosaceana (Harris), to the main component of its pheromone blend and traces of geometric isomer ((Z)11‐14:Ac and (E)11‐14:Ac, respectively) were recorded before and after 1 h of continuous exposure to pheromone in laboratory experiments, and 24 h of exposure under field conditions. Concentrations of pheromone ranging from 56 to below 1 ng mL^?1 air in Teflon chambers with regulated air exchange reduced peripheral sensory responses by 40–60% as measured by amplitudes of the EAG. Adaptation did not increase in a dosage‐dependent fashion over most of this range; an identical reduction of responsiveness was observed at each exposure to an effective concentration. Exposure of C. rosaceana at a loading dosage of 1 ng of pheromone in 100 µL of mineral oil (air concentration below the GLC detection limit) did not induce measurable adaptation. Caging C. rosaceana in apple trees adjacent to one, two or four Isomate OBLR/PLR Plus polyethylene pheromone dispensers for 24 h resulted in long‐lasting adaptation similar to that seen in laboratory experiments. Adaptation was not observed for C. rosaceana caged at a distance of 2 m from Isomate dispensers in 1‐ha plots treated with 500 dispensers per ha. Whenever observed, this type of adaptation was expressed for more than 5 min after exposure to pheromone ceased. Collectively, this adaptation phenomenon in C. rosaceana is consistent with the third of Zufall & Leinders‐Zufall's types of olfactory adaptation that is ‘long‐lasting’. Although the dosage of pheromone required to induce long‐lasting adaptation in this moth is judged high relative to that for normal sexual communication, we suggest this type of adaptation may come into play for some but not all moths under pest‐control regimes using the tactic of pheromone‐disruption, particularly those using high‐dosage release technologies like pheromone rope dispensers or Microsprayers.     

Field observations quantifying attraction of four tortricid moths to high-dosage pheromone dispensers in untreated and pheromone-treated orchards

Orientational responses of four species of feral tortricid moths (Lepidoptera: Tortricidae) to polyethylene tube dispensers of pheromone were observed in a 0.8 ha apple orchard treated with such pheromone dispensers and in an untreated 0.8 ha orchard. Male oblique‐banded leafrollers, Choristoneura rosaceana (Walker) (mean 7.2 ± 0.4 moths/night during 21 nights), Oriental fruit moths, Grapholita molesta (Busck) (mean 10.5 ± 2.1 during 20 evenings), and the redbanded leafrollers, Argyrotaenia velutinana (Walker) (mean 2.0 ± 1.1 during 14 nights) were observed approaching within 100 cm of their respective polyethylene‐tube pheromone dispensers in the untreated orchard. Furthermore, C. rosaceana (mean 2.0 ± 0.7 during 17 nights) and G. molesta (mean 1.5 ± 0.4 over 20 evenings) came within 100 cm of their respective polyethylene‐tube pheromone dispensers in the pheromone‐treated orchard. Most visits lasted less than 10 s, after which the majority of moths departed by flying upwind. In the untreated orchard, the number of C. rosaceana observed orienting to polyethylene tube dispensers was greater than the number captured in optimized monitoring traps (1.9 ± 0.4) per night of observation. The numbers of A. velutinana (2.0 ± 1.1) or G. molesta (10.5 ± 2.1) attracted to polyethylene‐tube dispensers in the untreated orchard did not differ statistically from the numbers captured in optimized monitoring traps per night of observation. In the pheromone‐treated orchard, the number of C. rosaceana (2.0 ± 0.4) or G. molesta (1.2 ± 0.2) observed orienting to polyethylene‐tube dispensers did not differ statistically from the numbers of male moths of these species captured in optimized monitoring traps per night of observation. No codling moths, Cydia pomonella L. were observed orienting to, or landing near, their respective polyethylene‐tube dispensers in either the untreated or pheromone‐treated orchards, although substantial numbers were captured in monitoring traps per night of observation (6.0 ± 1.7) in the untreated orchard. The attraction of male moths to polyethylene tube dispensers thus occurred in three of the four species observed. These results provide support for the idea that false‐plume‐following is an important component of the mechanisms mediating communicational disruption in moths by polyethylene‐tube dispensers.     

Pheromone release rate determines whether sexual communication of Oriental fruit moth is disrupted competitively vs. non‐competitively

Communicational disruption mechanisms for Oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), were determined using a suite of mathematical tools and graphical operations that enable differentiation between competitive attraction and non‐competitive mechanisms of disruption. Research was conducted in 20 field cages, each covering 12 mature apple trees. Commercial monitoring lures releasing Oriental fruit moth pheromone at a rate of 0.04 μg h^?1 and distributed at densities of 0, 1, 2, 4, 8, and 17 per cage were used to evaluate the effect of low‐releasing dispensers on the disruption of sexual communication. Graphical analyses revealed that near‐female‐equivalent pheromone dispensers disrupted Oriental fruit moth competitively. Commercial mating disruption dispensers releasing Oriental fruit moth pheromone at 60 μg h^?1 and deployed at 0, 4, 6, 10, 15, 20, and 30 per cage were used to evaluate the effect of high‐releasing dispensers on the disruption of sexual communication. Oriental fruit moth disruption shifted to a non‐competitive mechanism for high‐releasing dispensers. This is the first time such a shift in disruption mechanism has been demonstrated against a background of otherwise identical experimental conditions. Near‐female‐equivalent pheromone dispensers were also used to quantify the additive effect of an attract‐and‐remove control strategy compared with competitive mating disruption. We report a five‐fold reduction in Oriental fruit moth captures under attract‐and‐remove compared to mating disruption using near‐female‐equivalent dispensers. Surprisingly, release of female Oriental fruit moths into these large‐cage disruption studies had no measurable impact on male trapping.     

Development of 2‐phenylethanol plus acetic acid lures to monitor obliquebanded leafroller (Lepidoptera: Tortricidae) under mating disruption

We evaluated the effectiveness of 2‐phenylethanol (PET) in combination with acetic acid (AA) as a binary lure for monitoring male and female obliquebanded leafroller, Choristoneura rosaceana (Harris). Studies were conducted in apple, Malus domestica Borkhausen, orchards treated with or without sex pheromone dispensers for mating disruption (MD). Open polypropylene vials, closed membrane cups, and rubber septa loaded with AA and/or PET in varying amounts were first evaluated in a series of trapping experiments. Membrane cups loaded with 800 mg of PET were as effective as 10‐mg septa, but longer lasting, and were comparable to the open vials. A membrane cup AA lure was effective in tests, but further work is needed to increase its release rate and extend its activity. Catches of codling moth, Cydia pomonella (L.), and C. rosaceana were unaffected by combining PET with (E,E)‐8,10‐dodecadien‐1‐ol, the sex pheromone of codling moth, pear ester, (E,Z)‐2,4‐ethyl‐decadienoate and AA lures. Adding (E)‐4,8‐dimethyl‐1,3,7‐nonatriene to this blend to enhance codling moth catch significantly reduced catches of C. rosaceana. PET + AA was a more attractive binary lure than AA plus phenylacetonitrile (PAN) for C. rosaceana. The addition of PET or PAN to traps already baited with the sex pheromone of C. rosaceana significantly reduced male catches. Traps baited with PET + AA placed in blocks not treated with MD caught significantly fewer C. rosaceana than traps baited with sex pheromone. In comparison, sex pheromone‐baited traps in MD blocks caught ≤1 male moth per season which was significantly lower than total moth (>10) or female moth (≥3) catch in these blocks with PET + AA. A high proportion (>70%) of trapped females were mated in both untreated and MD‐treated orchards. Further refinement of this binary, bisexual lure using membrane cup technology may allow the establishment of action thresholds and improve management timings for C. rosaceana.     

Mating disruption of pea moth (Cydia nigricana) in organic peas (Pisum sativum)

We appraised mating disruption (MD) to control pea moth, Cydia nigricana (Fabricius) (Lepidoptera: Tortricidae), by assessing male attraction to monitor traps, larval pod infestation, and larval age structure in pheromone‐treated and untreated grain pea fields [Pisum sativum L. (Fabaceae)], over a 5‐year period. Cellulose pheromone dispensers were manually attached to the top shoots of pea plants and released 540 mg ha^?1 day^?1 synthetic pheromone E8,E10‐dodecadien‐1‐yl acetate in a first test series (2000–2001) and ca. 4 200 mg pheromone ha^?1 day^?1 in a second series (2004–2006). The dispensers had a half‐life of about 30 days. Although male attraction to pheromone monitoring traps was largely suppressed at the edges and within MD fields in both test series, MD treatments did not reduce pod infestation in the open field in 2000 and 2001. In the 2004–2006 series, larval damage reduction was achieved in the majority of the trials but overall MD efficacy in the open field was only 61% and not significant. In contrast, in field cages placed within the experimental sites and supplied with unmated pea moths, MD control was consistently high and significant. There were no obvious differences in the larval age distribution in all MD and control treatments, suggesting that infestations started and developed further similarly. As a univoltine species, C. nigricana larvae stay in the soil of pea fields for hibernation and pupate. The following year, emerging adults disperse and fly to the closest pea crop. Combined emergence site and pea crop treatments were conducted over 2 years to include this early migration phase of C. nigricana adults. However, the emergence site treatments did not enhance MD‐control efficacy. We conclude that mating activity was only prevented in cage tests, whereas substantial mating occurred during the transit phase outside the pheromone‐treated fields either within non‐crop vegetation and/or at the edges of pheromone‐treated pea fields orientated upwind. Thus, resulting gravid female entry can be regarded as the major constraint to reliable MD control.     

Optimization of pheromone dosage for gypsy moth mating disruption

The effect of aerial applications of the pheromone disparlure at varying dosages on mating disruption in low‐density gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), populations was determined in field plots in Virginia, USA during 2000 and 2002. Six dosages [0.15, 0.75, 3, 15, 37.5, and 75 g active ingredient (AI)/ha] of disparlure were tested during the 2‐year study. A strongly positive dose–response relationship was observed between pheromone dosages and mating disruption, as measured by the reduction in male moth capture in pheromone‐baited traps and mating successes of females. Dosages of pheromone 15 g AI/ha (15, 37.5, and 75 g AI/ha) reduced the mating success of females by >99% and significantly reduced male moth catches in pheromone‐baited traps compared to untreated plots. Pheromone dosages <15 g AI/ha also reduced trap catch, but to a lesser extent than dosages 15 g AI/ha. Furthermore, the effectiveness of the lower dosage treatments (0.15, 0.75, and 3 g AI/ha) declined over time, so that by the end of the study, male moth catches in traps were significantly lower in plots treated with pheromone dosages 15 g AI/ha. The dosage of 75 g AI/ha was initially replaced by a dosage of 37.5 g AI/ha in the USDA Forest Service Slow‐the‐Spread (STS) of the Gypsy Moth management program, but the program is currently making the transition to a dosage of 15 g AI/ha. These changes in applied dosages have resulted in a reduction in the cost of gypsy moth mating disruption treatments.     

Sex pheromone titre in the glands of Spodoptera litura females: circadian rhythm and the effects of age and mating

The present study investigates the effects of age and mating status on the circadian variations of gland sex pheromone titre in female Spodoptera litura Fabricius. Similar to other nocturnal moths, S. litura females exhibit circadian variations of gland sex pheromone contents, with higher levels during scotophase and lower levels during photophase. The sex pheromone titre in the glands peaks during the first scotophase after eclosion and sharply declines afterwards. Higher pheromone contents during scotophase may facilitate female reproductive activities, and the negative relationship between pheromone titre and female calling is likely the result of pheromone release during female calling. Interestingly, the present study demonstrates that mated S. litura females have significantly higher sex pheromone titre in their pheromone glands (PGs) than virgin females. This finding contrasts with all previous studies of other insect species, in which mating generally reduces the sex pheromone titre in female PGs. In S. litura, mating and male accessory gland fluids can suppress female calling behaviours and re‐matings. These results suggest that the suppression of female calling behaviours by mating and male accessory gland fluids may significantly reduce the release of sex pheromones and thus result in higher sex pheromone titre in the PGs of mated females.     

Pheromone pre-exposure and mating modulate codling moth (Lepidoptera: Tortricidae) response to host plant volatiles

Abstract 1 Two codling moth Cydia pomonella kairomonal attractants, ethyl (E,Z)‐2,4‐decadienoate (pear ester) and (E)‐β‐farnesene, were tested in an insecticide‐sprayed apple orchard and an orchard treated for mating disruption with synthetic pheromone (E,E)‐8,10‐dodecadienol (codlemone). Male captures with pear ester were higher in the pheromone‐treated than in the insecticide‐treated orchard, whereas captures with (E)‐β‐farnesene were not different. Subsequent wind tunnel experiments confirmed that pre‐exposure to sex pheromone codlemone increased the behavioural response of codling moth males to pear ester. This supports the idea that male attraction to the plant volatile pear ester and sex pheromone codlemone is mediated through the same sensory channels. 2 Pear ester is a bisexual codling moth attractant and even captures of female moths were significantly increased in the pheromone‐treated orchard. In the laboratory wind tunnel, pheromone pre‐exposure had no effect on female response to pear ester, but significantly more mated than unmated codling moth females flew upwind towards a pear ester source. Differences in mating status in insecticide‐treated vs. pheromone‐treated orchards may thus account for the differences in female trap captures with pear ester. 3 These findings are important with respect to monitoring of codling moth with pear ester in mating disruption orchards. They also emphasize the importance of host plant volatiles in pheromone‐mediated mating disruption, which has been neglected to date.     

Long‐term evaluation of field‐wide oriental beetle (Col., Scarabaeidae) mating disruption in blueberries using female‐mimic pheromone lures

The oriental beetle, Anomala orientalis (Waterhouse) (Col., Scarabaeidae), is the most important root‐feeding pest of blueberries and turfgrass in New Jersey, USA. Previous studies showed that mating disruption is a feasible option for oriental beetle management; however, assessing its efficiency can be challenging, and little is known on its long‐term effects. Accordingly, we conducted studies to investigate low‐dose pheromone lures equivalent to oriental beetle females (i.e. female mimics) as easy‐to‐use indicators of mating disruption success, determine the distance at which oriental beetle males respond to female‐mimic lures and assess the long‐term (3‐year) effects of mating disruption on oriental beetle populations in entire blueberry fields. Our studies showed that rubber septa baited with 0.3 μg of the oriental beetle sex pheromone (Z)‐7‐tetradecen‐2‐one attract similar numbers of males as compared with virgin females and can thus be used as a female mimic. The range of attraction of this lure was found to be also similar to virgin females and <30 m. In blueberries, mating disruption provided 87% inhibition of oriental beetle populations (trap shutdown) over a 3‐year period. Oriental beetle male captures in disrupted fields were threefold higher along the field edges than in the field interiors, indicating movement of males from nearby areas into the pheromone‐treated fields. In addition, mating disruption reduced male attraction to female‐mimic lures by 93% in all 3 years and reduced the number of larvae in sentinel potted plants in 1 of 2 years. These results show for the first time that mating disruption provides consistent long‐term field‐wide control of oriental beetle populations and that female‐mimic pheromone lures can be used as a new tool to assess oriental beetle mating disruption success.     

Conspecific females promote calling behavior in the noctuid moth,Pseudaletia adultera

Changes in female calling behavior in response to the presence of conspecific pheromones (pheromone autodetection) have been demonstrated in a number of moth species. However, the observed changes vary between species, and several ecological and adaptive explanations for autodetection have been proposed. We studied the effect of conspecific females on the calling behavior of the noctuid moth Pseudaletia adultera (Schaus) (Lepidoptera: Noctuidae, Hadenini), by comparing the age of first calling, as well as the onset and pattern of calling, when females were held individually or in the presence of conspecifics. Grouped females started calling at a lower age, a higher percentage of females called during the scotophase, and they called longer compared to females held in isolation. We also demonstrated that female antennae respond to each of the three main components of the sex pheromone – (Z)‐11‐hexadecen‐1‐ol, (Z)‐11‐hexadecen‐1‐yl acetate, and (Z)‐11‐hexadecenal – and that the response patterns differed from those of male antennae. By calling more and extending her calling window in presence of conspecific females, a female may increase her chances of accessing males. However, the potential benefits need to be considered within an ecological context, considering factors such as migration, oviposition, and foraging.     

Reduced antennal sensitivity, behavioural response, and attraction of male codling moths, Cydia pomonella, to their pheromone (E,E)-8,10-dodecadien-1-ol following various pre-exposure regimes

The effects of pre‐exposing male codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), to their pheromone (E,E)‐8,10‐dodecadien‐1‐ol (codlemone), in static and moving air, under laboratory and field conditions, on subsequent antennal sensitivity, behavioural responsiveness, and attraction to codlemone were investigated. In flight tunnel experiments, the percentage of moths wing fanning and taking flight were mostly unaffected, but upwind flight to, and contact with, pheromone sources known to elicit responses of both were shown to depend on the intensity and duration of previous exposure to codlemone and recovery time between exposure and assessment. Ten to 30‐min pre‐exposures to codlemone in static air (≈ 35 µg l^?1) not only caused a 99% reduction in attraction, but also significantly reduced electroantennogram response to codlemone. Recovery of full antennal sensitivity to codlemone took more than 1 h, but recovery of attraction took over 4 h, suggesting that habituation is also partially involved in reduced behavioural responsiveness following pre‐exposure. Seventy‐five min exposures to codlemone in moving air (5–10 cm s^?1) at rates of 0.9, 4.5, and 18 µg h^?1 from Celcon fibres caused 75, 86, and 99% disruption, respectively. However, 30–34‐h exposure of caged moths to air moving through an orchard treated with 1000 Isomate‐C® dispensers ha^?1 releasing approximately 20 µg h^?1 per dispenser during tests, had no impact on moth response in flight‐tunnel assays 30 min after removal from the orchard. In this treated orchard, catches of free‐flying moths in pheromone‐baited traps were completely inhibited. If observed mechanisms such as long‐lasting antennal adaptation or habituation of the central nervous system contribute to the disruption of pheromone communication among codling moths under field conditions, it seems unlikely that they occur following exposure to the average atmospheric concentrations of codlemone. For these effects to be important, codling moths may require close contact with pheromone sources for extended periods, or repeated close encounters.     

Calibration of an EAG system to measure airborne concentration of pheromone formulated for mating disruption of the pink bollworm moth, Pectinophora gossypiella (Saunders) (Lep., Gelechiidae)

Abstract: Electroantennogram (EAG) devices, used to measure airborne pheromone density in mating disruption experiments, so far have provided only ‘relative units’ of concentration rather than absolute concentration values. This paper describes a technique to measure the amount of pheromone delivered by calibration syringes into the Kaiserslautern EAG pheromone measurement device, thereby allowing such relative units of concentration to be converted into absolute concentrations. The synthetic pheromone used in these calibrations is of Pectinophora gossypiella (Saunders), the pink bollworm moth, and consists of a 1 : 1 mix of (Z,Z)‐ and (Z,E)‐7,11‐hexadecadienyl acetates. The syringe, driven as in field use, delivers its pheromone–air mixture into a glass capillary where it is adsorbed. The amount of pheromone trapped is measured by gas chromatography. The results show a linear relationship between the ratio of pheromone : silicone oil in a syringe and the pheromone concentration in the air puffs it generates. Efficacious mating disruption of P. gossypiella in cotton occurs with 10^?6 relative EAG units, which corresponds to an aerial pheromone density of 1.7 ± 0.15 ng/m³.     

Combined approaches using sex pheromone and pear ester for behavioural disruption of codling moth (Lepidoptera: Tortricidae)

Attractive properties of pear ester, ethyl (E,Z)‐2,4‐decadienoate, and codlemone, (E,E)‐8,10‐dodecadien‐1‐ol, the sex pheromone of codling moth, Cydia pomonella (L.), were utilized in experiments on behavioural disruption of mating. Standard dispensers loaded with codlemone alone or in combination with pear ester (combo) were applied at 500–1000/ha. Larger (10‐fold) combo dispensers (Meso) were evaluated at a rate of 80/ha. The addition of microencapsulated pear ester, PE‐MEC, sprayed with insecticides at 30 ml/ha was also evaluated. Male moth catches in unmated female‐baited traps were lower in standard combo dispenser than in codlemone dispenser–treated plots. Female moth catch in traps baited with the combination of pear ester, codlemone and acetic acid was lower in standard combo dispenser than in codlemone dispenser–treated plots. In 12 comparative experiments spanning from 2006 to 2012, male moth catch in unmated female‐baited traps was consistently and significantly lower in combo than in codlemone dispenser–treated plots. Male catch in codlemone‐baited traps did not differ between dispenser treatments in eight studies from 2006 to 2009. These results emphasize the benefit of alternatively using traps baited with unmated females over codlemone lures for the analysis of dispenser activity. Fruit injury was significantly reduced with the addition of PE‐MEC to insecticide applications across untreated and dispenser treatments. Proportion of unmated females trapped was higher in standard combo dispenser than in codlemone dispenser–treated and untreated plots. Similarly, the proportion of unmated females caught was higher in the Meso combo dispenser than in nearby or distant codlemone dispenser–treated plots. These field studies conducted in apple over 3 years demonstrate that adding pear ester both to pheromone dispensers, either standard or Meso, and to supplementary insecticide sprays can provide a significant increase in the disruption of sexual communication, reductions in female mating and reductions in fruit injury.     

Synergism of pheromone and host‐plant volatile blends in the attraction of Grapholita molesta males

Control of Grapholita molesta (Busck) (Lepidoptera: Tortricidae), a major pest of stone and pome fruits, is successfully achieved by mating disruption. Under these conditions, tools other than conventional pheromone dispensers are needed for flight monitoring. The objective of the present work was to determine whether plant volatiles synergize male G. molesta attraction to a suboptimal dose of synthetic sex pheromone. The plant blend (referred to as 5VB), a mixture of three green leaf volatiles [(Z)‐3‐hexenyl acetate, (Z)‐3‐hexenol, and (E)‐2‐hexenal] and two aromatics [benzaldehyde (BZA) and benzonitrile (BZN)], was added to the suboptimal pheromone dose (2 ng on filter paper) in log steps (up to 10 000× the pheromone dose) to test synergism of pheromone and plant blends. In addition, the effect of individual plant volatiles on male responses was investigated by adding to the suboptimal pheromone dose each of the four‐compound plant‐volatile blends, resulting from eliminating one volatile from the 5VB at a time, or each plant volatile alone. Flight behaviour and the time to reach the source were recorded. The 5VB alone was not attractive to G. molesta males, but at a ratio of 1:1 000 (Ph:5VB) or higher, the attractiveness of the suboptimal pheromone dose increased, to a level similar to that of the optimal pheromone dose (10 ng). All tested plant volatiles, except BZA, synergized the response to the pheromone when added individually, but only (Z)‐3‐hexenol and BZN did so to a level not significantly different from the Ph:5VB blend. Aromatics had a stronger effect than green leaf volatiles (GLVs), because their removal, but not the removal of GLVs, decreased landing responses. The addition of the 5VB decreased significantly the time males needed to reach the odour source. The observed enhanced male attraction to mixtures of pheromone and plant volatiles will facilitate the development of lures for G. molesta adult flight monitoring.     

Effects of sex pheromone in electrostatic powder on mating behaviour by Lobesia botrana males

Abstract:  In laboratory trials, mating behaviour of males of Lobesia botrana Den. and Schiff. (Lep., Tortricidae) was investigated after treatment with an electrostatically chargeable powder, Entostat^TM. Male moths were powdered with either blank Entostat or Entostat containing sex pheromone. Significantly more Entostat adhered to L. botrana males when sex pheromone was added to the powder compared with blank Entostat. Powdering male moths with Entostat, with or without sex pheromone, caused a significant reduction in antennal response when antennae were placed 2 cm away in downwind direction, while there was little effect when antennae were placed 25–100 cm from the EAG in downwind direction. In a flight study, powdering males of L. botrana caused significant increase in time before flight initiation and reduction in proportion of males making contact with calling females compared with untreated males. In a mating experiment in Petri dishes (to minimize required search time to locate female), significantly fewer females mated successfully (based on dissection of bursa copulatrix) when males had been treated with pheromone-loaded powder. Overall, powdering males of L. botrana caused considerable suppression of mating behaviour on various levels, and these suppressing effects were increased after adding sex pheromone to Entostat.     

Age related changes in the calling behaviour and the attractiveness of obliquebanded leafroller virgin females, Choristoneura rosaceana, under different constant and fluctuating temperature conditions

C. rosaceana (Lepidoptera: Tortricidae) virgin females initiated calling in the first scotophase following emergence at both 15° and 20°C constant temperature under a 16L:8D photoperiod. As females aged, the onset of calling occurred much earlier, and the time spent calling increased significantly at both temperature conditions. For a given age, the onset of calling occurred significantly earlier at 15°C than at 20°C, but the duration of calling did not vary with temperature. Similar results were obtained under warm and cold thermocycles that simulated natural conditions prevailing during the summer and fall flight periods. A comparison of the degree of attractancy of different-aged females (0, 3, and 5 days old) in the field showed that the attractiveness of 0-day-old females relative to that of 3-day old females did not vary between flights. However, compared to day-5 females, the relative attractiveness of 0- and 3-day-old females was greater in the summer than in the fall flights. The potential adaptative value of these changes for seasonal mating success are discussed.