Disruption of sexual communication in the mirid bug Lygocoris pabulinus by hexyl butanoate

1 The metathoracic scent gland in Lygocoris pabulinus contains mostly hexyl butanoate. As secretions of this gland in Heteroptera may serve as an alarm pheromone, we determined whether hexyl butanoate is released by disturbed bugs, and whether this compound disrupts sexual attraction of L. pabulinus males towards females. 2 Undisturbed males and females, and disturbed males released less than 100 ng/h hexyl butanoate, whereas disturbed females released a highly variable amount, ranging from 25 ng/h to more than 1 μg/h. 3 In the field, traps with virgin females and rubber septa containing 20 mg hexyl butanoate, caught a total of one male in a month. In control traps without hexyl butanoate, 36 males were caught in the same period. 4 In Y‐track olfactometer tests, males were not attracted to virgin females when a dispenser with 20 mg hexyl butanoate was placed in the bottle with females. Males were attracted to females when the dispenser was placed downwind from the females, but upwind from the point of male release. 5 These results suggest that males are not repelled by hexyl butanoate, but that this compound inhibits sex pheromone release in females. Application possibilities for pest management are discussed.     

Combining pheromone-baited and food-baited traps for insect pest control: Effects of additional control by parasitoids

Two age-structured population dynamic models are analyzed in which pheromone-baited trapping and food-baited trapping are used simultaneously to eradicate an insect pest. The pest species is assumed to be under partial control by a host-specific parasitoid species. The two models assume that density-dependent population regulation is accomplished either by host larval competition or by means of oviposition interference among the parasitoids. The two trap types interact in a positive synergistic manner and this combination appears to be very promising as a useful combination of pest control methods. Several features of the system are examined; the feature which appears to cause the greatest problem is the possibility of the parasitoids being attracted to the pheromone or the food traps. In either case, the degree of attraction does not have to be very great to undermine the control effort. It is seen that food trapping becomes indispensible if host pheromone is used by the parasitoids as a host-locating kairomone. If odor in the food traps is used by the parasitoids as kairomone, then the situation appears more optimistic, as the reduction in efficiency of the food traps appears much less than with the pheromone traps when pheromone acts as kairomone.     

Pheromone trapping models for insect pest control

Pheromones have recently been suggested for use in insect pest control. We formulate a discrete version of a model with virgin females (or female equivalent of pheromone) in traps, and explore conditions under which this mechanism can eradicate the pest. Our model is density independent, thus when eradication is not possible, the pest increases without bound, in reality density dependent effects limit population growth. Successive refinements incorporating various features, show that delayed mating together with monogamy has a strong influence on the outcome, whereas other aspects of mating behaviour are relatively unimportant. All our models show that when males are in excess control is impossible but when some virgins are left unmated each day the outcome depends on the parameters. As the birth rate or survivorship increase, control by this method becomes more difficult.     

Sampling plan for the coffee leaf miner Leucoptera coffeella with sex pheromone traps

The population density of the coffee leaf miner Leucoptera coffeella (Guérin-Méneville & Perrottet) (Lep., Lyonetiidae) can be estimated using pheromone traps in coffee fields as male capture reflects this pest damage based on previous correlational study. However, the spatial distribution of pheromone traps and their density are necessary to optimize the sampling procedure with pheromone traps. Therefore, the objectives of the present study were to determine the pheromone trap density required per hectare to sample coffee leaf miner populations and to determine the spatial distribution of the males of this pest species. The males were sampled every 8 days in 12 consecutive evaluations. Taylor's power law and frequency distributions were used to recognize the distribution of the male capture data, which followed a negative binomial distribution. A common K was obtained, allowing the establishment of a single conventional sampling plan for the 12 fields investigated. The adjusted sampling plan requires eight traps in an area of 30 ha for a 25% precision error. Kriging-generated maps allowed the simulation of male captures for 8, 12 and 20 traps per 30 ha and the results were compared with those obtained with absolute sampling resulting in R ²-values of 0.30, 0.57 and 0.60 respectively. The traps were able to identify the more highly infested areas within the field and are a precise and efficient tool for sampling populations of L. coffeella.     

Effect of sex pheromone emission on the attraction of Lobesia botrana

Since the discovery of Lobesia botrana Denis & Schiffermüller (Lepidoptera: Tortricidae) sex pheromone, it has played an important role in the control and detection of this pest, for example, through the use of pheromone‐baited traps and mating disruption techniques. Rubber septa are the most common pheromone dispensers used in monitoring traps, but often dispenser performance is not optimized. The key to improve methods based on pheromones as attractants (monitoring, mass trapping, or ‘attract and kill’) is to know the optimum emission interval, because release rates can strongly affect the attraction. In this work, five levels of pheromone load with different release rates were compared in traps using mesoporous pheromone dispensers to investigate the optimum release rate maximizing L. botrana catches. Residual pheromone loads of the dispensers were extracted and quantified by gas chromatography, to study release profiles and to estimate the various emission levels. The efficacy of pheromone emission was measured in field trials as number of moths caught. A quadratic model was fitted to relate the numbers caught vs. the daily emission rates. The resulting quadratic term was statistically significant, confirming the existence of a relative maximum for L. botrana catches. Taking into account that the trial was carried out only in one location, an optimum emission value of ca. 400 μg per day could be considered to enhance the attraction of L. botrana under West‐Mediterranean weather conditions.     

Models for mating disruption by means of pheromone for insect pest control

Models are presented to investigate the population dynamic behavior of a pest population with the release of pheromone for mating disruption. Three mechanisms of mating disruption are considered: (i) confusion of males, (ii) competition with female pheromone trails yielding false trail following, (iii) emigration of males prior to mating. In addition, several refinements to confusion are considered. Confusion and emigration of males were found to be very similar both quantitatively and dynamically; also, a combination of both mechanisms was very little more efficient than either one separately. False trail following is difficult to compare with the other two, since competition with wild females is involved and thus the total population size enters the equations. Density dependence of the action of pheromones results in some cases in which mating disruption cannot control the pest population. Similarly, aggregation of the pest population decreases the efficiency of the method unless the pheromone action is density independent. Delayed mating of females makes control easier, and may constitute one mechanism for mating disruption.     

Relative abundance and flight phenology of two pheromone types of Acrobasis nuxvorella (Lepidoptera: Pyralidae)

Two synthetic sex pheromones have been developed and are currently used to detect the flight of the pecan nut casebearer, Acrobasis nuxvorella Neunzig, the most damaging pest of pecan [Carya illinoinensis (Wangenh.) K. Koch]. One pheromone (referred to as standard) is attractive to moths in the southern United States, but not in Mexico. The other pheromone (referred to as Mexican) is attractive to moths in the southern United States and in Mexico. These two pheromones have been implemented by producers as an important tool in monitoring the activity of this pest and have allowed for more efficient pesticide use. In the future, these pheromones could be used as a means of population reduction through pheromone based control methods. Trapping data taken over a 3-yr period were used to determine if phenological differences exist between pheromone types of pecan nut casebearer. The relative abundance of each pheromone type at several locations in the United States also was evaluated. Results of this study indicate that no phenological differences exist between the two pheromone types studied in the United States and that significantly more males are attracted to field-deployed pheromone traps baited with the standard pheromone than to traps baited with the Mexican pheromone.     

Molecular identification of six species of scale insects (Quadraspidiotus sp.) by RAPD-PCR: assessing the field-specificity of pheromone traps

The San-José Scale Quadraspidiotus perniciosus (SJS) is a quarantine pest in Switzerland. Its occurrence is monitored by trapping males on glue traps treated with artificial female sex pheromone that is supposed to be species-specific. However, large numbers of males were caught in locations where, for ecological reasons, this species was not expected to occur, suggesting that the pheromone is attractive for one or several otrter scale species. Because no morphological species determination key is described for males of this genus, it was not possible to test this hypothesis until now. We used randomly amplified polymorphic DNA (RAPD-PCR) to establish a molecular identification key for six European Quadraspidiotus species. Because the glue used on the traps proved to be an excellent preservative, this key enabled us to identify males caught on pheromone traps in the field and to assess the species-specificity of the SJS-pheromone.     

Influence of proportion of (4S)-cis-verbenol in pheromone bait on Ips typographus (Col., Scolytidae) catch in pheromone trap barrier and in single traps

Abstract:   The possibilities of increasing catching efficiency of male Ips typographus L in pheromone traps barriers and in single traps were tested. Pheromone dispensers with different percentages of (4S)- cis -verbenol (cV) in pheromone mixtures were used. The results show that the different male catching efficiencies of pheromone trap barriers and single traps were related to the different percentages of cV in the pheromone bait. The proportions of males were higher in pheromone trap barriers than in single traps. Thus increasing the catch of males in pheromone trap barriers is possible by using a combination of pheromone traps containing pheromones giving a higher release of cV with others containing pheromones giving a lower release of cV .     

Female sex pheromone of Athetis lepigone (Lepidoptera: Noctuidae): Identification and field evaluation

Athetis lepigone has been recorded in many countries in Europe and Asia, but it had never been documented as an agricultural pest until 2005. For the purpose of using the sex pheromone to control this pest, we conducted a study to identify the sex pheromone of A. lepigone by gas chromatography with an electroantennographic detector (GC‐EAD) and GC coupled with mass spectrometry (GC/MS) analyses. Three pheromone candidates were detected by GC‐EAD analysis in the extracts of the female sex pheromone gland, and two candidates were identified as (Z)‐7‐dodecenyl acetate (Z7‐12:OAc) and (Z)‐9‐tetradecenyl acetate (Z9‐14:OAc) in a ratio of 1:5 by mass spectral analysis of natural pheromone components and dimethyl disulphide adducts. In the field male trapping test, the traps baited with the binary blend captured high number of males, while traps with single component hardly caught males, indicating that the two components are essential for the male attractiveness. In addition, the optimum ratios of Z7‐12:OAc and Z9‐14:OAc were determined as 3:7–7:3, and the best doses for the binary blend (at ratio of 3:7 between Z7‐12:OAc and Z9‐14:OAc) were 0.25–0.5 mg/trap, based on the number of male catches. The identification of a highly attractive sex pheromone will help in developing efficient strategies for monitoring and control of A. lepigone.     

Optimum spacing of pheromone traps for monitoring the coffee leaf miner Leucoptera coffeella

Pest monitoring with pheromone traps is affected mainly by factors such as trap placement and pest biology. The intertrap distance can affect the capture due to competition among traps that are placed at short distances. We studied the interference among pheromone traps used to monitor males of the coffee leaf miner, Leucoptera coffeella (Guérin‐Méneville) (Lepidoptera: Lyonetiidae), with traps placed at various distances. Using geostatistical analysis, we determined at what distance captures were independent from other traps. Traps were placed in groups of 12 with distances among traps per group either 2, 5, 10, 15, or 30 m. Traps were checked for males every 4 days during 16 days. We found interference between traps when intertrap distances were shorter than 10 m. The range and magnitude of spatial dependence varied considerably among each sampling date and wind direction. For directions of 45° and 135°, the traps should be placed 110 and 177 m apart, respectively, to obtain spatially independent counts and therefore representative samplings for assessing the insect population in the area. These results have implications for developing sampling plans for managing L. coffeella with pheromone traps; the spatial analysis indicated that a trap density of one pheromone trap for every 3.5–4 ha would be adequate for the monitoring of the coffee leaf miner.     

Combining pheromone-baited and food-baited traps for insect pest control: Effects of developmental period

An age-structured population dynamics model is presented that incorporates pheromone-trapping and food-trapping as control methods for an insect pest. The model yields the following results. Low rates of pest survivorship allow lower trapping rates for control. Species with long developmental periods are easier to control than those with shorter developmental periods (other factors being equal) due to lower net survival. The rates of pheromone trapping alone for effective control are usually very high. The combination of pheromone and food trapping allows control with much lower trapping rates than either method alone. Even small amounts of immigration of adult pests into the control area renders pheromone control ineffective, whereas food traps suppress both the immigrants and the resident population. Food- (or odor-) baited traps which attract both males and females are only somewhat more efficient than those which attract females alone. The existence of density-dependent population regulation assists the control program substantially, but this assistance declines as food trapping becomes a more important part of the control program. Larval competition strongly affects the required trapping rates for eradication; species in which all larvae exert strong competition are much easier to control than those in whic the younger larvae contribute little to the total competitive depression.     

New aspects of the biology of the Melanesian rfhinoceros beetle Scapanes australis (Col., Dynastidae) and evidence for field attraction to males

Scapanes australis is a major coconut pest, endemic in Papua New Guinea. Early in the night, males placed singly into artificial galleries made in young coconut palms exhibited a sex specific calling behaviour for 1 to 1.5 h. Coming to the gallery entrance, they raised the abdomen and the hind legs, the head lowered inside the gallery, and emitted a liquid secretion, rhytmically smeared by crossing the legs. Females which did not behave so, were very mobile. The adult flying period coincided with the male calling behaviour. In field assays with caged insects on coconut palms, attraction of both sexes to males was evidenced when they were calling. Males fought for gallery possession at a male arrival. No aggression but mating was observed with arriving females, which proved not to have developed oocytes. The strong male attractionwas confirmed using automatic traps, baited with one lived male in a sugarcane piece. Male were assumed to release an aggregation pheromone. Further studies are underway to identify the putative pheromone.     

Movement of the grape berry moth, Endopiza viteana: displacement distance and direction

Abstract. Mark–release–recapture is used to quantify displacement by adults of the North American grape berry moth, Endopiza viteana Clemens (Lepidoptera: Tortricidae) under field conditions. Moths marked with fluorescent dust are released eight times in the centre of a vineyard over 2 years, and recaptured using pheromone traps and interception traps. In vineyards, male moths are recaptured an average of 13.8 ± 0.8 m from the release site (maximum 58.2 m), whereas female displacement is similar with average flight distances of 11.4 ± 6.7 m (maximum 41.2 m). Increasing wind speed during moth flight activity periods suppresses displacement by both sexes, and females are less likely than males to fly in winds above 0.6 m s^?1. The majority of males are recaptured upwind from the release site or at a tangent to the overall mean wind direction when responding to pheromone traps, whereas female moths trapped in interception traps exhibit a large variability in direction from the release point. Releases of marked moths in woods adjacent to a vineyard demonstrates interhabitat movement by E. viteana males and by a single female. The average maximum displacement by males during interhabitat movement is 105.4 ± 3.9 m, significantly greater than the average maximum of 39.7 ± 6.7 m inside the vineyard habitat.     

The relative performance of pheromone and light traps in monitoring the seasonal activity of both sexes of the eastern hemlock looper, Lambdina fiscellaria fiscellaria

The seasonal flight activity of both sexes of the eastern hemlock looper, Lambdina fiscellaria fiscellaria Guenée (Lepidoptera: Geometridae) was studied during two consecutive years in Quebec and Newfoundland, using light (L), pheromone (P) and combined light and pheromone (LP) traps. Moth density significantly affected the performance of the different traps, with P traps being more effective at low than high density. However, P trap catches decreased just prior to the onset of female captures, probably as a result of competition between traps and virgin calling females. Nearly all females caught in L and LP traps were already mated and even the first females caught had laid at least half of their egg complement. In Quebec under warm nights, the pattern of male activity occurred at different times, with peak P catches being later in the scotophase than those of L traps, but overall similar numbers of males were caught in both traps. In contrast, under cool nights, males were caught early in the night in both P and L traps, suggesting a strong competition effect between traps, although more males were caught in P than L traps overall. In Newfoundland, the pattern of male captures in L and P traps was similar at both high and low temperatures, so competition between trap types would always be high. Under these conditions P traps were more effective than L traps. Irrespective of the region, year or temperature, significantly more males were captured in LP, with the effect of L and P being additive. In both regions, females responded similarly to L and LP traps with peak activity occurring early in the night. Captures of females were lower than those of males under cool temperatures, suggesting that the temperature threshold for flight is higher for females. The use of L and P traps simultaneously and/or in combination is discussed in relation to integrated pest management programs and ecological considerations.     

Development and evaluation of an emulsified paraffin wax dispenser for season-long mating disruption of Grapholita molesta in commercial peach orchards

The University of California at Davis patented the use of emulsified wax to release pheromones for mating disruption. Advantages of these dispensers include low cost, self-adhesion, and biodegradation. We compared the efficacy and practicality of Confuse-OFM, a commercial emulsified wax formulation of oriental fruit moth, Grapiholita molesta (Busck), pheromone with those of Check-Mate OFM-F sprayable pheromone and Isomate-M 100 polyethylene tube dispensers in commercial peach (Prunus spp.) orchards. Efficacy was measured with male captures in pheromone-, virgin female-, and liquid attractant-baited bucket traps as well as by noting injury to shoots and fruit. Two applications of Confuse-OFM were as effective as two applications of CheckMate OFM-F and one application of Isomate-M 100. However, Confuse-OFM was tedious to apply and wasted pheromone with an initially high release rate. We developed a new emulsified wax formulation (Wax Dollops) that maintained release rates above a 5 mg/ha/h threshold twice as long as Confuse-OFM in the laboratory. Field trials confirmed that one application of 3-ml dollops (590 dollops per ha) provided season-long (approximately 15 wk) control equivalent to that of Isomate-M 100 and Confuse-OFM applied as described above. Several applicators were developed for Wax Dollops, including a pneumatic gun that shot dollops >2 m. However, the most efficient method for application was wiping dollops onto tree branches by using a flat-bladed spatula. This research was the basis for a new line of commercial pheromone pest control products equally effective to current commercial formulations but with advantages in cost and flexibility.     

Do sexual pheromone traps provide biased information of the local gene pool in the pine processionary moth?

Abstract 1 Sexual pheromone traps are commonly used to monitor populations of the pine processionary moth, Thaumetopoea pityocampa, assuming that trapped males are representative of the breeding population. 2 For seven Italian populations, mitochondrial haplotypes (COI and COII) of adult males caught in traps were compared with those of larvae obtained from egg batches laid in the same year, to test whether the males trapped were representative of the local populations. 3 The distribution of haplotype frequencies revealed substantial homogeneity between adult males and larvae samples from the same population, except for Aosta Ruines Verrès, a population recently expanding in the south‐western Alps. In this case, the results suggested that trapped males were recruited over a wider area than local moths because haplotype diversity was higher than that of larvae. 4 A further analysis of this population using nuclear markers (AFLP) confirmed that adults, collected in pheromone traps, were genetically different from the larvae emerging in the same stand. 5 In conclusion, the assumption that trapped males are representative of breeding populations was confirmed for core populations, but has not been verified for the recently established population of Aosta Ruines Verrès. This should encourage discussion with respect to the reliability of pheromone traps in monitoring programmes of the pest, especially at the range's edge.     

Effect of irradiation on dispersal ability of male sweetpotato weevils (Coleoptera: Brentidae) in the field

We used the mark-and-recapture method in the field to test the effect of gamma radiation on the dispersal ability of the male sweetpotato weevil, Cylas formicarius elegantulus (Summers) (Coleoptera: Brentidae), a serious sweetpotato pest in Japan. To evaluate the dispersal ability of male sweetpotato weevil, we released 27,218 males (13,302 males irradiated with a dose of 200 Gy and 13,916 nonirradiated males) in two replications (September and October 2005). Each replication lasted 5 d from the release of weevils to the removal of traps, and male weevils were released twice (1 and 3 d before trap setting). Forty pheromone traps were placed in lines corresponding to eight compass directions and five distance classes (20, 50,100, 200, and 500 m) in each replication. We captured 2,263 irradiated males (17.0%) and 2,007 nonirradiated males (14.4%) in the two replications. Six irradiated and eight nonirradiated males were captured in the traps 500 m far from the release point. All parameters to evaluate the dispersal ability of irradiated male sweetpotato weevil (recapture rate, dispersal distance, and dispersal direction) were similar to nonirradiated males in three of the four trials. However, parameters were different between irradiated males and nonirradiated males in one trial. Because the majority of parameters consistently show that the similarity of the dispersal ability, we considered that male sweetpotato weevil irradiated with a dose of 200 Gy possessed equal dispersal ability to that of nonirradiated males in the field.     

Control of Ichneumonoptera chrysophanes (Meyrick) (Lepidoptera: Sesiidae) by mating disruption in persimmons

Abstract A ca 0.62 ha block of 480 persimmon trees at Woombye, Queensland, was treated with the pheromone of Ichneumonoptera chrysophanes emitted from polyethylene dispensers placed at a rate equivalent to 1480/ha early in September 2000. A second block of 219 trees was left untreated and served as the control. The technique was assessed using traps to measure the ability of I. chrysophanes males to locate synthetic pheromone baits, and by the incidence of fresh damage detected during December and June surveys of a minimum of 67 trees in each block. Pheromone release rates were determined approximately weekly by measuring the amount of pheromone remaining in a sample of 10 dispensers suspended within the treated block. A second orchard at Amamoor, Queensland, was partly treated with pheromone applied at a similar rate, but was monitored only in terms of trap catch. No assessments were made of damage levels. Mean pheromone-release rates ranged from 15.8 to 1.6 mg/ha/h. Over the entire period of the trial, from 8 September 2000 to 27 June 2001, no males were caught in any of the 12 traps in the pheromone-treated block of the Woombye orchard, while 944 were caught in the five traps in the untreated block. The proportion of trees with fresh damage was significantly higher in the untreated block (0.188 and 0.567; December and June surveys, respectively) than in the treated block (0.027 and 0.205), although there was no significant difference between treatments in the mean number of strikes/infested tree in either survey. In the Amamoor orchard no moths were caught in any of the 32 traps in the treated blocks, compared with a total of 303 in the 13 traps in the untreated block.     

Small‐plot studies comparing pheromone and juice baits for mass‐trapping invasive Synanthedon myopaeformis in Canada

Recent introduction of Synanthedon myopaeformis (Borkhausen) (Lepidoptera: Sesiidae) into organic apple‐growing areas of Canada has stimulated research on semiochemical‐based management of this European pest. Replicated, small‐plot (0.16 ha) experiments were conducted to compare sex pheromone, 3Z,13Z‐octadecadienyl acetate (10 mg), Concord grape juice (300 ml), or their combination, as mass‐trapping lures at trap densities equivalent to 12.5, 25, 50, and 100 traps ha^?1. Total numbers of male and female moths removed from test plots increased significantly with trap density in all juice‐based mass‐trapping experiments. In pheromone mass‐trapping experiments, however, total catches of males did not increase significantly as trap densities were increased and catches appeared to plateau with 25–50 traps ha^?1. With pheromone‐based mass‐trapping, significantly fewer males were caught in pheromone‐baited assessment traps at the centre of each mass‐trapping plot than in identical traps in untreated plots. This reduction is indicative of significant trap interference or trap ‘shut‐down’. Increasing the density of juice‐based mass‐trapping had no effect on catches of male or female moths in juice‐baited assessment traps, indicating a short range of attraction and lack of interference between juice traps. Pheromone‐ and juice‐based mass trapping removed similar numbers of males at each trap density tested, respectively, but summed catches of males and females were greatest with juice baits. Combining pheromone and juice into a single mass‐trapping treatment (50 traps ha^?1) did not significantly increase catches of males or females relative to either treatment alone. If a practical bisexual mass‐trapping system is going to be developed for S. myopaeformis, then identification of volatile kairomones in Concord grape juice may be useful.