Epiphyas Postvittana Research Articles

Odorant Receptors from the Light brown Apple Moth (Epiphyas postvittana) Recognize Important Volatile Compounds Produced by Plants

Moths recognize a wide range of volatile compounds, which they use to locate mates, food sources, and oviposition sites. These compounds are recognized by odorant receptors (OR) located within the dendritic membrane of sensory neurons that extend into the lymph of sensilla, covering the surface of insect antennae. We have identified 3 genes encoding ORs from the tortricid moth, Epiphyas postvittana, a pest of horticulture. Like Drosophila melanogaster ORs, they contain 7 transmembrane helices with an intracellular N-terminus, an orientation in the plasma membrane opposite to that of classical GPCRs. EpOR2 is orthologous to the coreceptor Or83b from D. melanogaster. EpOR1 and EpOR3 both recognize a range of terpenoids and benzoates produced by plants. Of the compounds tested, EpOR1 shows the best sensitivity to methyl salicylate [EC(50) = 1.8 x 10(-12) M], a common constituent of floral scents and an important signaling compound produced by plants when under attack from insects and pathogens. EpOR3 best recognizes the monoterpene citral to low concentrations [EC(50) = 1.1 x 10(-13) M]. Citral produces the largest amplitude electrophysiological responses in E. postvittana antennae and elicits repellent activity against ovipositing female moths. Orthologues of EpOR3 were found across 6 families within the Lepidoptera, suggesting that the ability to recognize citral may underpin an important behavior.

PESTS OF BLUEBERRIES ON SÃO MIGUEL, AÇORES, PORTUGAL

In February and March 2006, two plots of 154 plants each of three southern high bush blueberries cultivars (Vacciniurn corymbosum 'Emerald', 'Jewel', and 'Springhigh') were planted in two locations on Sao Miguel Island, Acores, Portugal. One plot was planted near the town of Furnas, where the native mountain blueberry Vacciniu,n cylindraceuin was also planted, and a second plot, was planted near Calhetas with high bush only. At Caihetas, blueberry plantation establishment was difficult due to heavy soil, high pH and low organic matter, and only 10% of the plans survived. The blueberries at Furnas established well and leaf rust, caused by Pucciniasinun vaccinii, was observed. Symptoms included distinct yellow foliar lesions, with brown reddish pustules later in the season. 'Jewel' had the most rust infection, followed by 'Emerald' and 'Springhigh'. Foliar lesions of the rust were not observed on any of the native, V. cylindraceuin seedlings. This fungal disease exists in other European blueberry growing regions and can be managed with fungicidal sprays. The greenhouse thrips, Heliothrips haemorrhoidalis and the light brown apple moth, Epiphyas posivittana infested each of the blueberry species and was/were observed at both locations. The heaviest infestation of thrips was observed on plants of native V. cyIindraceun. The blueberry insect complex in the Azores is not very different from that in other locations where blueberries are grown and corresponding control measures are available.

Sensory Neurons in the Drosophila Genital Tract Regulate Female Reproductive Behavior

Females of many animal species behave very differently before and after mating. In Drosophila melanogaster, changes in female behavior upon mating are triggered by the sex peptide (SP), a small peptide present in the male's seminal fluid. SP activates a specific receptor, the sex peptide receptor (SPR), which is broadly expressed in the female reproductive tract and nervous system. Here, we pinpoint the action of SPR to a small subset of internal sensory neurons that innervate the female uterus and oviduct. These neurons express both fruitless (fru), a marker for neurons likely to have sex-specific functions, and pickpocket (ppk), a marker for proprioceptive neurons. We show that SPR expression in these fru+ ppk+ neurons is both necessary and sufficient for behavioral changes induced by mating. These neurons project to regions of the central nervous system that have been implicated in the control of reproductive behaviors in Drosophila and other insects.

Crystal Structure of Epiphyas postvittana Takeout 1 with Bound Ubiquinone Supports a Role as Ligand Carriers for Takeout Proteins in Insects

Takeout (To) proteins are found exclusively in insects and have been proposed to have important roles in various aspects of their physiology and behavior. Limited sequence similarity with juvenile hormone-binding proteins (JHBPs), which specifically bind and transport juvenile hormones in Lepidoptera, suggested a role for To proteins in binding hydrophobic ligands. We present the first crystal structure of a To protein, EpTo1 from the light brown apple moth Epiphyas postvittana, solved in-house by the single-wavelength anomalous diffraction technique using sulfur anomalous dispersion, and refined to 1.3 angstroms resolution. EpTo1 adopts the unusual alpha/beta-wrap fold, seen only for JHBP and several mammalian lipid carrier proteins, a scaffold tailored for the binding and/or transport of hydrophobic ligands. EpTo1 has a 45 angstroms long, purely hydrophobic, internal tunnel that extends for the full length of the protein and accommodates a bound ligand. The latter was shown by mass spectrometry to be ubiquinone-8 and is probably derived from Escherichia coli. The structure provides the first direct experimental evidence that To proteins are ligand carriers; gives insights into the nature of endogenous ligand(s) of EpTo1; shows, by comparison with JHBP, a basis for different ligand specificities; and suggests a mechanism for the binding/release of ligands.

Vegetation increases the abundance of natural enemies in vineyards

Non-crop areas can increase the abundance of natural invertebrate enemies on farmland and assist in invertebrate pest control, but the relative benefits of different types of vegetation are often unclear. Here, we investigated abundance of natural enemies in vineyards with edges consisting of different types of vegetation: remnant native forests, wooded margins planted after establishment of the crop (hereafter called shelterbelts), or pasture. Invertebrates were sampled four times using canopy sticky traps and ground level pitfall traps, replicated across two seasons at one of the sites. The distribution and abundance of natural enemies in relation to edges with adjacent vegetation or pasture were mapped by distance indices (SADIE) and compared with ANOVAs. There was a positive influence of adjacent wooded vegetation on staphylinids, predatory thrips, predatory mites, spiders, ladybird beetles and hymenopteran parasitoids including Trichogramma egg parasitoids in the canopy and/or at ground level, although there were significant differences among sites and groups of organisms. In contrast, pasture edges had no effect or a negative effect on numbers of natural enemies in vineyards. To directly assess potential beneficial effects of adjacent vegetation, predation and parasitism of eggs of a vineyard insect pest, Epiphyas postvittana Walker (Lepidoptera: Tortricidae), was measured. Parasitism by Trichogramma was higher adjacent to remnant vegetation while predation was not affected. These results indicate that the abundance and distribution of vineyard natural enemies and parasitism of pest moth eggs is increased adjacent to edges with wooded vegetation, leading to beneficial effects for pest control. The conservation of remnant woodland and planting of shelterbelts around vineyards may therefore have direct economic benefits in terms of pest control, whereas non-crop pasture may not produce such benefits.

Expression levels of aminopeptidase‐N genes in the lightbrown apple moth, Epiphyas postvittana

AbstractFive aminopeptidase‐N genes (EpAPN1‐5) of the tortricid moth Epiphyas postvittana have been isolated from a midgut expressed sequence tag (EST) library. Relative RNA expression of these genes was measured by quantitative reverse transcription polymerase chain reaction using actin as a reference gene. Measurements were made on various tissues of fifth instar larvae, over all stages of the life cycle and under differing dietary conditions: different protein sources and levels, and in presence of trypsin and metalloprotease inhibitors. Gene expression for all five genes was the greatest in midgut tissue, but was also detected in the hindgut, fat body and Malpighian tubules. EpAPN4 was consistently the highest expressed, with EpAPN3 at about half that level; EpAPN5 was the least expressed. During larval stages expression was high, generally increasing over the instars, after an early peak as neonates or first instars. Expression in other life stages was much lower. Males and females showed differing expression in the pupal and adult stages: female expression was higher in the pupa, this reversed in the adult. Gene expression levels and ratios both changed with diet. A natural apple leaf diet depressed levels. Diets with the most impaired amino acid balance induced the greatest change; generally EpAPN1 increased by the greatest proportion. The addition of proteinase inhibitor also increased gene expression, and it was noteworthy that the trypsin inhibitor addition, which has been shown to double aminopeptidase activity, also doubled levels of gene expression.

Microbial population and diversity on the exoskeletons of four insect species associated with gorse (Ulex europaeus L.)

AbstractFungi and bacteria on the external surfaces of four gorse‐associated insect species: gorse seed weevil Apion ulicis Förster (Coleoptera: Apionidae), light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae), were recovered by washing and plating techniques. The isolates were identified by morphology and polymerase chain reaction (PCR) restriction fragment length polymorphism and sequencing of internally transcribed spacer (ITS) and 16S rDNA. A culture‐independent technique (direct PCR) was also used to assess fungal diversity by direct amplification of ITS sequences from the washings of the insects. All insect species carried Alternaria, Cladosporium, Corallomycetella, Penicillium, Phoma, Pseudozyma spp. and entomopathogens. Ninety‐four per cent of the 178 cloned amplicons had ITS sequence similarity to Nectria mauritiicola (syn. Corallomycetella repens). E. postvittana carried the largest fungal spores (spore mean surface area of 126 μm2) and the most fungal colony forming units per insect. Methylobacterium aquaticum and Pseudomonas lutea were isolated from all four insect species. P. fluorescens was the most abundant bacterium on the lepidopteran insects. This study presents the diversity of microbial taxa on insect exoskeletons, and provides the basis for developing a novel mycoherbicide delivery strategy for biological control of gorse using insects as vectors of a plant pathogen.

Expressed sequence tags and proteomics of antennae from the tortricid moth, Epiphyas postvittana

Genomic and proteomic analyses of the antennae of the light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) were undertaken to identify genes and proteins potentially involved in odorant and pheromone binding and turnover. An EST approach yielded 5739 sequences, comprising 808 contigs and 1545 singletons. InterPro and Blast analyses revealed members of families implicated in odorant and pheromone binding (PBPs, GOBPs, ABPXs and CSPs) and turnover (CXEs, GSTs, CYPs). Of the three pheromone binding proteins (PBPs) identified, two were more highly expressed at the RNA and protein levels in adult male antennae (EpPBP1, EpPBP3), while a third was more highly expressed in female antennae (EpPBP2). To identify proteins involved in the detection of sex-specific signals, differential 2D gel electrophoresis (pH 5-8) followed by mass spectrometry was conducted on antennal proteins from males versus females. Identified male-biased proteins included a pheromone binding protein, a porin, a short chain dehydrogenase/reductase, and a member of the takeout family.

New Zealand lessons may aid efforts to control light brown apple moth in California

New Zealand's major fruit industries are dependent upon producing high-quality crops for export with a very low incidence of pest damage. Light brown apple moth was an economically important pest within the fruit sector in the 1960s through the 1980s, and it developed resistance to broad-spectrum insecticides. The increase in its pest status focused research on biological control, and existing native natural enemies were augmented with new introductions from Australia in the late 1960s. By the early 1990s, this effort resulted in substantially reduced leafroller populations and fruit damage. The implementation of integrated pest management (IPM) programs in the New Zealand fruit sector in the mid-to late 1990s practically eliminated the use of broad-spectrum organophosphate insecticides, further enhancing natural control. Today light brown apple moth is successfully managed in IPM and organic programs through a combination of biological control and threshold-based applications of selective insecticides.

Odour quality discrimination for behavioural antagonist compounds in three tortricid species

AbstractThe antennal and behavioural response of three tortricid species (Lepidoptera: Tortricidae) to their corresponding sex pheromones and known or putative behavioural antagonists was tested by electroantennography and in field trials. The species and their pheromones and known or proposed behavioural antagonist were lightbrown apple moth, Epiphyas postvittana (Walker) [pheromone: 95% (E)‐11‐tetradecenyl acetate (E11‐14Ac) and 5% (E,E)‐9,11‐tetradecadienyl acetate (E9E11‐14Ac); antagonist: (Z)‐11‐tetradecenyl acetate (Z11‐14Ac)], codling moth, Cydia pomonella (L.) [pheromone: (E,E)‐8,10‐dodecadien‐1‐ol (codlemone); antagonist: (E,E)‐8,10‐dodecadienyl acetate (codlemone acetate)], and gorse pod moth, Cydia ulicetana (Haworth) [pheromone: (E,E)‐8,10‐dodecadienyl acetate (codlemone acetate); putative antagonist: (E,E)‐8,10‐dodecadien‐1‐ol (codlemone)]. In all three species, the antennal response to the antagonists was not significantly different from the antennal response to con‐specific sex pheromone compounds. In the field trapping experiments, significantly fewer males of all three species were attracted to the respective pheromone when blended with the behavioural antagonist compound. However, this response varied between the species, with lightbrown apple moth and codling moth showing stronger responses to the antagonist compounds than gorse pod moth. Both lightbrown apple moth and codling moth males were able to discriminate between pure pheromone and pheromone blended with the antagonist when placed in traps side‐by‐side separated by ca. 10 cm. The presence of the behavioural antagonist not only affected the catch of males of both species within their own traps but also affected the catch in the neighbouring trap that contained con‐specific sex pheromone; the catch of gorse pod moth was not reduced by the presence of codlemone in the neighbouring trap. These results suggest that strong behavioural antagonists such as codlemone acetate for codling moth and Z11‐14Ac for lightbrown apple moth induce their inhibition effect at a substantial distance downwind from the odour source; however, most of those males that were able to overcome this inhibition effect at the early stage of orientation to odour source, were able to discriminate between the pheromone source and the pheromone source admixed with behavioural antagonist. Moderate behavioural antagonists such as codlemone for gorse pod moth did not elicit a discrimination effect.

Light brown apple moth's arrival in California worries commodity groups

Light brown apple moth is an exotic pest that was confirmed in California in March 2007. It is a tortricid leaf-roller moth native to Australia, which has a broad range of plant hosts with the capacity to cause damage across a wide array of crops, natural areas and ornamental plants. California and federal agencies have issued quarantine orders affecting production and retail nurseries, and potentially fruit and vegetable exports. It is found thus far primarily in nurseries near urban areas. Eradication efforts are under way to prevent its spread into California crop areas and throughout the United States.

Expressed sequence tags from the midgut of Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae)

The midgut is a key tissue in insect science. Physiological roles include digestion and peritrophic membrane function, as well as being an important target for insecticides. We used an expressed sequence tag (EST) approach to identify candidate genes and gene families involved in these processes in the light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae). Two cDNA libraries were constructed from dissected midgut of third to fifth instar larvae. Clustering analysis of 6416 expressed sequence tags produced 1178 tentative unique genes comprising 725 tentative contigs and 453 singletons. The sequences show similar codon usage to sequences from other lepidopterans, a Kozak consensus sequence similar to Drosophila and single nucleotide polymorphisms (SNPs) were detected at a frequency of 1.35/kb. The identity of the most common Interpro families correlates well with major known functions of the midgut. Phylogenetic analysis was conducted on representative sequences from selected multigene families. Gene families include a broad range of digestive proteases, lipases and carbohydrases that appear to have degradative capacity against the major food components found in leaves, the diet of these larvae; and carboxylesterases, glutathione-S-transferases and cytochrome P450 monooxygenases, potentially involved in xenobiotic degradation. Two of the larger multigene families, serine proteases and lipases, expressed a high proportion of genes that are likely to be catalytically inactive.

SPRAYING UPSET IN CALIFORNIA

AMID PROTESTS and legal battles, large swaths of the agriculturally intensive Monterey Bay and Santa Cruz areas in Northern California are being sprayed with pheromone-based pesticides in hopes of warding off an infestation of the crop-damaging light-brown apple moth. The controversy harks back to the 1980s and ’90s, when attempts to wipe out the Mediterranean fruit fly in California with widespread aerial spraying of the pesticide malathion generated public outcry. In September, areas of Monterey County were sprayed for the light-brown apple moth, and more spraying was scheduled to begin in Santa Cruz County on Nov. 5. Citizens groups and local governments have attempted several times to halt the spraying, saying the risk to humans from widespread exposure to the pheromones has yet to be determined. On Nov. 5, a federal judge denied a temporary restraining order request filed by Santa Cruz County residents, and the spraying program is scheduled to resume as soon as ...

Host range testing of a nucleopolyhedrovirus of the lightbrown apple moth <i>Epiphyas postvittana</i>

Epiphyas postvittana nucleopolyhedrovirus (EppoNPV) has considerable potential as a biocontrol agent or biopesticide for control of lightbrown apple moth Epiphyas postvittana a pest of horticultural crops in New Zealand and a market access problem in export fruit To obtain regulatory approval for EppoNPV in either role EppoNPV must not negatively impact on nontarget organisms In this study eight nontarget insect species from one hymenopteran and five lepidopteran families were inoculated with EppoNPV at high titre (109 PIB/ml) Larval survival growth rates pupation and pupal weights were measured and larvae examined for EppoNPV Minor differences in one parameter were found in Helicoverpa armigera and Cydia pomonella but no viral infection Growth and survival were compromised in virusfed individuals in only one species Tyria jacobaeae The majority of T jacobaeae larvae had high microsporidal infections and EppoNPV polyhedra were found in only one larva suggesting a very low likelihood of field infectivity

Effects of EppoNPV infection on gene expression in <i>Epiphyas postvittana</i> larvae

The nucleopolyhedrovirus EppoNPV can control larvae of the leafroller Epiphyas postvittana in the field but has varying effects on New Zealands other leafroller pests An understanding of the infection process at the genetic/molecular level within the leafroller complex may lead to strategies to enhance the effectiveness of the virus Microarray technology was used to examine the effects of viral infection on gene expression levels in E postvittana gut tissue The results show that a 5 day infection with EppoNPV caused a significant downregulation of several E postvittana genes many of which were consistent with a response to injury or stress or with the triggering of apoptosis (such as components of the oxidative phosphorylation pathway) The majority of the expressed viral sequences detected are structural genes and genes associated with late gene expression These data provide a basis from which to compare EppoNPV infection in other less susceptible leafroller species

A proteinase inhibitor from Nicotiana alata inhibits the normal development of light-brown apple moth, Epiphyas postvittana in transgenic apple plants

Insecticidal proteins are a potential resource to enhance resistance to insect pests in transgenic plants. Here, we describe the generation and analysis of the apple cultivar 'Royal Gala' transgenic for Nicotiana alata (N. alata) proteinase inhibitor (PI) and the impact of this PI on the growth and development of the Epiphyas postvittiana (light-brown apple moth). A cDNA clone encoding a proteinase inhibitor precursor from N. alata (Na-PI) under the control of either a double 35S promoter or a promoter from a ribulose-1,5-bisphosphate carboxylase small sub-unit gene (rbcS-E9 promoter) was stably incorporated into 'Royal Gala' apple using Agrobacterium-mediated transformation. A 40.3 kDa Na-PI precursor protein was expressed and correctly processed into 6-kDa proteinase inhibitors in the leaves of transgenic apple lines. The 6-kDa polypeptides accumulated to levels of 0.05 and 0.1% of the total soluble protein under the control of the rbc-E9 promoter and the double 35S promoter, respectively. Light-brown apple moth larvae fed with apple leaves expressing Na-PI had significantly reduced body weight after 7 days of feeding and female pupae were 19-28% smaller than controls. In addition, morphological changes such as pupal cases attached to the wing, deformed wings, deformed body shape, and pupal cases and curled wings attached to a deformed body were observed in adults that developed from larvae fed with apple leaves expressing Na-PI, when compared to larvae fed with the non-transformed apple leaves.

Field electroantennogram and trap assessments of aerosol pheromone dispensers for disrupting mating in Epiphyas postvittana

An electronically controlled aerosol system for mating disruption was evaluated against Epiphyas postvittana Walker in apple orchards in New Zealand. The area in which male moths were affected by the aerosol system was examined using catches in traps radiating from a central single-point source of either one aerosol can dispenser or 100 polyethylene tubing dispensers, compared with catches in orchard plots without pheromone dispensers. Both pheromone dispensing systems decreased moth catch to similar levels at 5-10 m from the central release point, but there was 5.5-fold more pheromone released from aerosol cans than from polyethylene dispensers over a 24 h period. Trap catches were reduced by about 90% in plots treated with either five aerosol cans per hectare or uniform deployment of polyethylene dispensers. Recordings of electroantennograms in open grassed plots and orchards indicated that the treated cotton pad of an aerosol dispenser and a point source of 100 polyethylene tubing dispensers produced similar electroantennogram recordings. Electroantennogram recordings provided evidence that pheromone plume detection from a single-point source was maintained over a range of 5-40 m downwind in the orchard. On present evidence, aerosol pheromone dispensers could not be recommended for further testing towards control of E. postvittana under New Zealand conditions owing to their higher cost of purchase and operation.

Increasing vineyard floral resources may not enhance localised biological control of the leafroller Epiphyas postvittana (Lepidoptera: Tortricidae) by Dolichogenidea spp. (Hymenoptera: Braconidae) parasitoids

In agroecosystems, the efficacy of biological control exerted by many parasitoids is predicted to be enhanced where the availability of floral resources is increased. Such resources may attract parasitoids and enhance their longevity and fecundity. In Hawke's Bay, New Zealand, this prediction was tested by adding varying quantities of potted flowering alyssum (Lobularia maritima) (Brassicaceae) to plots containing apple plants (Malus domestica) inoculated with larvae of the leafroller, Epiphyas postvittana (Lepidoptera: Tortricidae). In two replicated trials, over 90% of the parasitoids from recovered larvae were Dolichogenidea spp. (Hymenoptera: Braconidae). In both trials increasing the percentage of alyssum did not result in a corresponding increase in the leafroller parasitism rate. Instead, the primary influence on parasitism rates was due to Dolichogenidea spp. dispersing from a nearby orchard. A significant negative correlation was observed in leafroller parasitism as a function of distance from this orchard. A vineyard to the north of the study site also influenced parasitism rates. Our results suggest the orchard was a regional source population for this parasitoid, and the abundance of local resources such as alyssum did not influence parasitoid foraging. At the level of our entire study block, our effective area of resource provision was 0.1%. A level of resource provision higher than that used in this study may be necessary to test for a positive influence on local parasitism rates. From our results, it appears that for parasitoids with relatively high dispersal rates, the availability of local resources may not be as important as a regional source population.

Genome of the most widely used viral biopesticide: Anticarsia gemmatalis multiple nucleopolyhedrovirus

The genome of Anticarsia gemmatalis multiple nucleopolyhedrovirus isolate 2D (AgMNPV-2D), which is the most extensively used virus pesticide in the world, was completely sequenced and shown to have 132 239 bp (G+C content 44.5 mol%) and to be capable of encoding 152 non-overlapping open reading frames (ORFs). Three ORFs were unique to AgMNPV-2D, one of which (ag31) had similarity to eukaryotic poly(ADP-ribose) polymerases. The lack of chiA and v-cath may explain some of the success and growth of the AgMNPV biological control programme, as it may explain the high recovery of polyhedra sequestered inside dead larvae in the field, which are collected and used for further application as biological pesticides in soybean fields. The genome organization was similar to that of the Choristoneura fumiferana defective MNPV (CfDefNPV). Most of the variation between the two genomes took place near highly repetitive regions, which were also closely associated with bro-coding regions. The separation of the NPVs into groups I and II was supported by: (i) a phenogram of the complete genomes of 28 baculovirus and Heliothis zea virus 1, (ii) the most parsimonious reconstruction of gene content along the phenograms and (iii) comparisons of genomic features. Moreover, these data also reinforced the notion that group I of the NPVs can be split further into the AgMNPV lineage (AgMNPV, CfDefNPV, Epiphyas postvittana NPV, Orgyia pseudotsugata MNPV and C. fumiferana MNPV), sharing eight defining genes, and the Autographa californica MNPV (AcMNPV) lineage (AcMNPV, Rachiplusia ou NPV and Bombyx mori NPV), sharing nine defining genes.

Differentiation of Competitive vs. Non-competitive Mechanisms Mediating Disruption of Moth Sexual Communication by Point Sources of Sex Pheromone (Part 2): Case Studies

Eleven out of 13 disruption profiles (plots of dispenser density vs. male catch) from moth sex pheromone literature were consistent with a competitive-attraction mechanism, in which dispensers attract males and thereby divert them from females. Mean dispenser activity (D(a)) across all competitive-attraction cases was 0.04 +/- 0.06 (SD); values ranged from 0.0005 for a tiny laminated flake dispenser of racemic disparlure targeting gypsy moth to 0.2 for polyethylene tube dispensers used against lightbrown apple moth. A dispenser application activity (D(Aa)) can be calculated by multiplying D(a) by the number of such dispensers applied per hectare of crop. The highest dispenser application activity (D(Aa)) values approached 200 and corresponded to >99% inhibition of catches of male moths in monitoring traps. Relative to the D(Aa) scale, % inhibition of catches of male moths compressed and obscured large differences in D(Aa) when % disruption exceeded 90%. For cases of competitive attraction, these two efficacy scales can be interconverted by using the formula: D(Aa) approximately = 100/(100 minus % disruption). When disruptive point sources of pheromone were directly observed, male moths were seen approaching pheromone dispensers whose disruption profiles matched competitive attraction. Two cases fit non-competitive disruption mechanisms, which include camouflage, desensitization (adaptation and/or habituation), and sensory imbalance. In these cases, pheromone was released at rates higher than for cases of disruption by competitive attraction. Practical ramifications of the finding that competitive attraction appears to be the prevalent mechanism for moth mating disruption by pheromone point sources are listed. We believe that the congruence of diverse sets of mating disruption field data with explicit a priori predictions validates competitive-attraction theory. The analytical tools and principles governing competitive attraction that were uncovered during this study of mating disruption of moths should be generally applicable to competitive-attraction phenomena.