Lightbrown Apple Moth Epiphyas Research Articles

First record of a possible predatory collembolan species, Dicyrtoma fusca (Collembola: Dicyrtomidae), in New Zealand

AbstractSpecimens of a previously unrecorded collembolan species were found in a field margin of a commercial dairy farm near Christchurch, New Zealand. They were consistently observed apparently feeding on egg batches of the light brown apple moth Epiphyas postvittana, which were being used as bait to assess predation rate by potential biocontrol agents. The collembolan specimens were identified as the European species Dicyrtoma fusca based on published morphological descriptions of this species. DNA sequence data of the New Zealand specimens clustered with sequence data from GenBank of this species from Norway and England, confirming that D. fusca populations in New Zealand originated from Europe. A GenBank sequence had previously identified a collembolan species from Estonia as this species, but its position in the phylogeny indicates that it is a different species. Some morphological variations observed in arrangement of macrochaetae on the head were shown by sequence data to be intraspecific differences only.

Is the Combination of Insecticide and Mating Disruption Synergistic or Additive in Lightbrown Apple Moth, Epiphyas postvittana?

Pest suppression from combinations of tactics is fundamental to pest management and eradication. Interactions may occur among tactical combinations and affect suppression. The best case is synergistic, where suppression from a combination is greater than the sum of effects from single tactics (AB >> A+B). We explored how mating disruption and insecticide interacted at field scale, additively or synergistically. Use of a pheromone delivery formulation (SPLAT™) as either a mating disruption treatment (i.e. a two-component pheromone alone) or as a lure and kill treatment (i.e. the two-component pheromone plus a permethrin insecticide) was compared for efficacy against the lightbrown apple moth Epiphyas postvittana. Next, four point-source densities of the SPLAT™ formulations were compared for communication disruption. Finally, the mating disruption and lure and kill treatments were applied with a broadcast insecticide. Population assessment used virgin female traps and synthetic pheromone in replicated 9-ha vineyard plots compared with untreated controls and insecticide-treated plots, to investigate interactions. Lure and kill and mating disruption provided equivalent suppression; no additional benefit accrued from including permethrin with the pheromone suggesting lack of contact. The highest point-source density tested (625/ha) was most effective. The insect growth regulator methoxyfenoxide applied by broadcast application lowered pest prevalence by 70% for the first ten weeks compared to pre-trial. Pheromone addition suppressed the pest further by an estimated 92.5%, for overall suppression of 97.7% from the treatment combination of insecticide plus mating disruption. This was close to that expected for an additive model of interactivity between insecticide and mating disruption (AB = A+B) estimated from plots with single tactics as 98% suppression in a combination. The results indicate the need to examine other tactical combinations to achieve the potential cost-efficiencies of synergistic interactions.

Modeling the potential global distribution of light brown apple moth Epiphyas postvittana (Lepidoptera: Tortricidae) using CLIMEX

Light brown apple moth Epiphyas postvittana is a significant horticultural pest native to Australia that currently has a limited global distribution. However, this pest can tolerate very heterogeneous climates and has a wide host range. It has recently established in California with considerable consequences for US international and domestic trade. It has resulted in increasing calls for targeted risk assessment so that appropriate quarantine measures can be put in place to prevent its entry into new regions and further spread. Potential global distribution has been predicted by comparing the climatic conditions of its native (Australia) and long-established (New Zealand) ranges to the rest of the world using CLIMEX. It was suggested that E. postvittana has potential to establish mainly in countries in Central and South America, southern Africa, Western Europe and Southeast Asia. The study provides basic information for further assessment of the establishment capacity of this species in new habitats, and adds to the knowledge required to make science-based decisions in biosecurity.

Using insects as potential vectors of Fusarium tumidum to control gorse

The adult light brown apple moth Epiphyas postvittana Walker (Lepidoptera: Tortricidae), gorse seed weevil Apion ulicis Förster, (Coleoptera: Apionidae), gorse pod moth Cydia ulicetana Denis and Schiffermüller (Lepidoptera: Tortricidae) and gorse thrips Sericothrips staphylinus Haliday (Thysanoptera: Thripidae) were assessed for their ability to carry and deposit the conidia of a plant pathogenic fungus Fusarium tumidum Sherb. on agar plates in laboratory experiments. Epiphyas postvittana, the largest insect species studied, carried and deposited the highest number of F. tumidum conidia. The number of colony forming units recovered from all insect species after exposing them to F. tumidum sporulating cultures for 24 h, declined with time. In subsequent transmission experiments using only E. postvittana, each insect was loaded with 5,000 conidia of F. tumidum and caged together with potted healthy gorse (Ulex europaeus L.) at eight insects per plant. The insects deposited 310 conidia per plant on average but neither infection nor plant growth effects resulted. Only directly inoculated plants became infected and were significantly shorter with 42% reduction in fresh shoot weight compared with the control treatment. Epiphyas postvittana on its own did not cause any significant plant damage and did not enhance F. tumidum infection. The insect did not spread the conidia from diseased to healthy plants. The results showed that insects are unlikely to be effective vectors in a ‘lure-load-infect’ approach for biological control of gorse using F. tumidum.

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.

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.

Plant and host effects on the leafroller parasitoid Dolichogenidia tasmanica

AbstractParasitism by the braconid wasp Dolichogenidia tasmanica of first instar larvae of the lightbrown apple moth Epiphyas postvittana, established on four different species of potted host plants, was assessed after 2 weeks of field exposure in an apple orchard. Parasitism varied significantly between larval host plants (apple 58%, broom 59%, clover 30%, poplar 19% ). Parasitism on potted apple seedlings of the co‐evolutionary host, E. postvittana, was compared in a field trial with that of two native New Zealand leafroller species (to which D. tasmanica has had exposure for 5 decades only). Parasitism varied significantly with larval host (E. postvittana, 83%; Ctenopseustis herana, 58%;Planotortrix octo, 26% ). Larval collections were made from mature apple trees and identification of larvae was achieved by DNA analysis for the leafroller species using PCR‐RFLP of ITS1 + ITS2, and for the parasitoid by specific PCR of partial 18S. Parasitism under natural field conditions on mature apple trees was not different between larval hosts (mean 32.5% ). In laboratory studies, more P. octo larvae departed in response to parasitoid probing behaviour than E. postvittana, which is likely to contribute to the difference in parasitism rates. This study conclusively shows that D. tasmanica parasitises native New Zealand leafrollers, despite their different evolutionary origins.

Variations in life history traits and flight capacity among populations of the light brown apple moth Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae)

Variations in life history traits and flight capacity among populations of the light brown apple moth Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae)

Bacillus thuringiensisδ-Endotoxin Binding Sites in Two Lepidoptera,Wiseanaspp. andEpiphyas postvittana

Proteins from the midguts of the light-brown apple mothEpiphyas postvittana(Walker) and the porina caterpillarsWiseana cervinata(Walker),W. copularis(Meyrick), andW. jocosa(Meyrick) which bind theBacillus thuringiensisδ-endotoxin Cry1Ba were characterized using Cry1Ba labeled with Bolton and Hunter reagent. A comparison of two iodine labeling techniques on the toxicity ofB. thuringiensisδ-endotoxins showed that labeling using chloramine-T substantially decreased Cry1Ba toxicity against the light-brown apple mothE. postvittana,whereas labeling using the Bolton and Hunter reagent had no effect on the toxicity of either Cry1Ac or Cry1Ba to this insect. The characteristics of Cry1Ac binding sites fromE. postvittanamidguts were determined by competitive binding assays using toxin labeled with125I by both methods. The difference in values of binding site characteristics found by the two methods was shown to be caused by modification of the toxin by the conditions of chloramine-T labeling. The relationship between number and affinity of the binding sites and the toxicity of the δ-endotoxins is discussed.

Modelling insecticide residues on kiwifruit foliage: Effect of residue age on insecticide activity and concentration

Abstract Chlorpyrifos EC was applied at a range of rates to kiwifruit leaves in an experiment designed to test the adequacy of a published residue decay and activity model for the case of insecticide on kiwifruit. Treated leaves were sampled over a period of 51 days following spray application, with residue levels determined by chemical assay, and residue toxicity to lightbrown apple moth Epiphyas postvittana assessed by bioassay and logit regression analysis. Residue activity indexed as the residue level for 90% mortality (LR90) was shown to decline substantially as residues aged from 2 to 51 days. A log residue‐log time model was shown to be a more robust representation of residue decay characteristics than the exponential model frequently used.

Spatial discrimination between sources of pheromone and an inhibitor by the light-brown apple mothEpiphyas postvittana (Walker) (Lepidoptera: Tortricidae)

Inhibition of the behavioral responses of maleEpiphyas postvittana moths by theZ isorner of the major component of the sex pheromone,E11-14: OAc, was studied in a wind tunnel. Inhibition was detectable at a Z isomer concentration of 10% that of the major component and was greatest when it was added to the same source as the pheromone. Inhibition declined rapidly as the inhibitor was moved across-wind away from the pheromone source but was largely maintained when the sources were separated upwind or downwind. The results showed that the insects possess a high degree of temporal resolution for odor plumes of different composition.

Correlation of azinphosmethyl resistance with detoxication enzyme activity in the light brown apple moth Epiphyas postvittana (Lepidoptera: Tortricidae)

Bioassay using diet incorporation of azinphosmethyl showed six strains of light brown apple moth to have varying levels of resistance to azinphosmethyl (3- to 15-fold) compared with three susceptible strains. Two of these strains were products of a selection and backcrossing program providing resistant insects that had a common genome with that of one of the susceptible strains. Individual male moths from each strain were tested for (i) glutathione S-transferase and (ii) non-specific esterase activity. Larvae were assayed for (iii) mixed function oxidase activity. Each enzyme group was assayed with two substrates. Significant positive regressions between LC 50 and enzyme activity were observed for all three groups: (i) r 2 = 0.84 for 3,4-dichloronitrobenzene conjugation, (ii) 0.64 for α-naphthyl acetate hydrolysis, 0.54 for α-naphthyl butyrate hydrolysis, and (iii) 0.88 for p-nitroanisole oxidation and 0.86 for aniline oxidation. No correlation with the LC 50 was found for 1-chloro-2,4-dinitrobenzene conjugation ( r 2 = 0.001). Activities of all three groups were significantly higher in the two backcross resistant strains compared to the susceptible parent strain ( P < 0.05). The gene(s) for high enzyme activity had thus been successfully transferred with the factor for resistance. The results suggest a close relationship between detoxication enzyme activity and azinphosmethyl resistance.

Insecticide Resistance in the Light Brown Apple Moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae): Larval Response to Azinphosnlethyl

Azinphosmethyl resistance in the light brown apple moth Epiphyas postvittana (Walker) was confirmed with four methods: topical application of larvae, a Potter tower direct-spray method, and two residue exposure methods using middle instars and newly hatched larvae. The Mariri population exhibited a 140-fold resistance factor, using topical application of larvae. A 20-fold resistance factor was obtained by using a Potter tower to spray the insects directly. The first residue exposure method, using a Potter tower to treat apple leaf discs with the 50 WP formulation, produced a 13-fold resistance factor when third- and fourth-instar larvae were caged on the discs for 48 h. In the second residue exposure method, when first-instar larvae were caged onto leaf discs for 16 h, the resistance factor was 5-fold. The Potter tower, acetone-spray method was found to be the most satisfactory technique for evaluation of azinphosmethyl resistance in larvae. The application of this technique for monitoring resistance in the field is suggested.

Resistance to a nuclear polyhedrosis virus in the light-brown apple moth Epiphyas postvittana (Lepidoptera: Tortricidae)

Measurements were made of the relative susceptibility to a nuclear polyhedrosis virus of three populations of light-brown apple moth Epiphyas postvittana: a resistant laboratory strain (CAN), a susceptible laboratory strain (BAR), and a field population. CAN was found to be 50 times more resistant than BAR and 160 times more resistant than the field line. Experiments on hybrid crosses of resistant and susceptible strains showed that resistance is genetically determined. This serves as a warning of the possible selection of virus-resistant strains of insect pests, where viral insecticides are being used in the field.

Post-harvest disinfestation of apples of the light-brown apple moth Epiphyas postvittana

A range of dosages of methyl bromide used according to different chamber and fru:. I+ temperatures, preceded, unaccompanied or followed by cold treatment was found effective in disinfesting apples of the light-brown apple moth, Epiphyas postvittana (Walker), in Tasmania, 1972-1 974. Fumigations were in 1.1 m3 and 14.3 m3 chambers, for 2 or 2+hours, loaded to 40 or 80 per cent of their capacities, and cold storage was for 21 days at 0�C. The disinfestation treatments were tested on apples artificially infested with neonate and fourth instar larvae and on a field line of naturally infested fruit; the onset of fumigation effects on fourth instar larvae in artificial medium was also determined.