Archips Argyrospilus Research Articles

Variation in response to insecticides in two species of univoltine leafrollers (Lepidoptera: Tortricidae)

AbstractPopulations of fruittree leafroller, Archips argyrospila (Walker), and European leafroller, Archips rosana L., were obtained from eight sites in the Okanagan Valley, British Columbia, and assayed for their responses to five insecticides using a leaf-disk bioassay and neonate larvae. Lethal concentration ratios (LCR values) were calculated for all populations compared with the most susceptible strain, and significant variation was detected in both species. LCR values ranged from 1.04 to 9.06 for azinphosmethyl, from 1.29 to 53.15 for tebufenozide (Confirm®), from 1.85 to 24.69 for methoxyfenozide (Intrepid®), from 1.59 to 2291.4 for indoxacarb (Avaunt®), and from 1.92 to 1.98 for spinosad (Success®). Methoxy fenozide was approximately 100-fold more toxic to neonate leafrollers than was tebufenozide, and spinosad was the most toxic of all materials tested. Correlation analysis indicated that there was cross-resistance between azinphosmethyl and tebufenozide. At the LC50 level, the responses of the two species were not significantly different for each insecticide. Analysis of equivalency and parallelism of dose-response lines revealed that A. argyrospila and A. rosana had equivalent responses to azinphosmethyl. LC50 values for the response of A. argyrospila to azinphosmethyl were not different from values obtained almost 20 years earlier. Cross-resistance between azinphosmethyl and tebufenozide suggests that resistance management for these two species of univoltine leafrollers should not include rotation of azinphosmethyl and benzoylhydrazine insect-growth regulators. The high level of resistance to indoxacarb found in one population indicates that baseline tolerance screening is desirable before indoxacarb is introduced for use in Canadian orchards.

Timing, magnitude and causes of flower and immature fruit loss in pin cherry and choke cherry

Pin cherry (Prunus pensylvanica L.) and choke cherry (Prunus virginiana L.) are two wild fruit species with potential for commercial production, but information about fruit production is limited. The objectives of this study were to determine, for both species, the timing and magnitude of flower and immature fruit loss, and to determine the primary causes of this loss, including the effects of pollen source and supplemental pollination. Sequential sampling of both pin cherry and choke cherry indicated that the primary period of abscission occurred during the first 3 wk following full bloom. Final fruit set ranged from 32.6 to 44.7% of flower number for pin cherry, and from 3.7 to 20.1% for choke cherry. Insect damage accounted for only 14% of the total observed flower and fruit abscissions in pin cherry and 7% in choke cherry. The major insect pest causing this loss in pin cherry was a sawfly (Hoplocampasp., Tenthredinidae) and in choke cherry, a leaf-roller (Archips argyrospila, Tortricidae). A controlled pollination experiment was used to determine the effects of pollen source and supplemental pollination on pin cherry and choke cherry. Final fruit set for flowers that were cross-pollinated by hand in both pin cherry (mean of 51.3%) and choke cherry (mean of 56.9%) in most cases was significantly greater than flowers that were open-pollinated, self-pollinated, or not pollinated. These data suggested that the majority of flower and immature fruit loss in both pin cherry and choke cherry resulted from a lack of pollination and/or fertilization. Key words: Choke cherry, pin cherry, flower loss, immature fruit loss, pollination, insect damage

Impacts of seasonal kaolin particle films on apple pest management

AbstractThe impact of multiple applications of the kaolin-based particle film M96-018 on the population density of selected pests of apple, Malus domestica (Borkh) (Rosaceae), and their natural enemy populations were measured in several Washington State orchards from 1997 to 1999. Densities of western tentiform leafminer, Phyllonorycter elmaella (Doganlar and Mutuura) (Lepidoptera: Gracillariidae), were significantly higher and percent parasitism was generally lower in treated plots than in untreated plots. The effect of M96-018 on green aphids (Aphis spp.) (Hemiptera: Aphididae) was variable between orchards; however, populations of rosy apple aphid, Dysaphis plantaginea Passerini (Hemiptera: Aphididae), were higher in treated plots than in untreated plots. M96-018 reduced the mean density of the white apple leafhopper, Typhlocyba pomaria (McAtee) (Hemiptera: Cicadellidae), and the density of spiders (Araneae) compared with untreated plots. Fruit injury by codling moth, Cydia pomonella (L.), and fruittree leafroller, Archips argyrospilus (Walker) (Lepidoptera: Tortricidae), was significantly reduced in the treated plots compared with the untreated plots. The effect of M96-018 on the mullein bug, Campylomma verbasci (Meyer) (Hemiptera: Miridae), was variable between orchards and years. Stink bug (Hemiptera: Pentatomidae) density and related fruit injury were unaffected by M96-018. Fruit infestation by San Jose scale, Quadraspidiotus perniciosus (Comstock) (Hemiptera: Diaspididae), was significantly higher in treated plots than in untreated plots. Discontinuing applications of M96-018 at mid-season reduced the number of aphid-infested leaves and increased fruit injury by leafroller compared with a full-season program. No differences in pest densities occurred in plots treated for one versus two consecutive years; however, the density of phytophagous mites (Acari: Tetranychidae) was significantly higher the subsequent year after plots were treated with M96-018. Further studies are needed to elucidate how these disruptive impacts of particle films can be minimized.

Molecular Phylogeny Within and Between Species of the <I>Archips argyrospila</I> Complex (Lepidoptera: Tortricidae)

The Archips argyrospila complex consists of a series of morphologically indistinct populations with a confusing array of pheromone and host types. No phylogenetic studies on the genus Archips or any of its species groups have previously been published. We examined DNA variation in a 475 bp segment of the mitochondrial COI gene and compared 30 populations of A. argyrospila, four populations of A. mortuana, four populations of A. goyerana, and one specimen of each of four outgroup species. Among the 97 ingroup sequences obtained, there were 23 unique haplotypes and nucleotide variation at 20 sites. The monophyletic ingroup containing A. argyrospila, A. mortuana, A. goyerana and a West Coast clade was strongly supported by bootstrap values and decay indices. Host races and some pheromone types within A. argyrospila did not correspond to mtDNA variation in this analysis. Our molecular analyses supported phylogenetic and ecological interpretations of species status applied to A. goyerana but not A. mortuana, and supported the existence of a phylogenetically distinct West Coast species.

Prevalence of Viral Diseases of the Fruittree Leafroller, Archips argyrospila (Walker) (Lepidoptera: Tortricidae), in Louisiana

A nucleopolyhedrovirus (NPV) and a granulovirus (GV) were found infecting field populations of fruittree leafroller, Archips argyrospila (Walker), larvae in Louisiana. Both viruses were recovered from infected larvae at 7 of 8 widely separated sampling sites. Additionally, a small proportion (<5%) of the larvae (maximum 10.2%) had double infections. Overall, infection rates ranged from 0 to 24.4 percent and were statistically correlated with defoliation and host population levels in a positive, density-dependent manner. It appears that though high populations and warm temperatures favor development of a widespread epizootic, the leaf rolls (shelters) protect larvae from contamination at low to moderate population levels. At outbreak larval densities, the rates of viral prevalence approached 25 percent, and the viruses, coupled with other natural control factors may, in time, become effective in population control.

Incomplete barriers to mitochondrial gene flow between pheromone races of the North American pine engraver,Ips pini(Say) (Coleoptera, Scolytidae)

The pine engraver Ips pini (Say) is known to include three pheromone races, but gene flow between these races has not been investigated. We used maternally inherited mitochondrial DNA (mtDNA) variation to infer gene flow between 22 widely distributed North American populations of I. pini for a total of 217 individuals, based on 354 bp of the cytochrome oxidase I gene. Gene flow was estimated cladistically as migrants per generation (Nm) and as haplotype variation between populations (Nst). Three distinct mtDNA haplotype lineages, generally corresponding to eastern (I), Rocky Mountain (II) and western (III) regions of North America, were resolved with a total of 34 distinct I. pini haplotypes. The distributions of these lineages were largely congruent with the geographical ranges of the 'New York', 'California' and 'Idaho–Montana' pheromone races. Only individuals with lineage I mtDNA were observed among eastern populations, whereas individuals with lineage II or III mtDNA predominated among western populations. Gene flow (Nm and Nst) was generally moderate between all populations. However, the presence of lineage I mtDNA on the eastern side of western North America and the absence of lineage II and III mtDNA in eastern North America suggest directional gene flow from east to west. These results indicate that female-controlled assortative mating among pheromone races may disrupt gene flow between conspecifics, reflecting incomplete pre-mating barriers.

Characterisation of Cydia pomonella granulovirus from codling moths in a laboratory colony and in orchards of British Columbia*

SummarySequence analyses indicate that a granulovirus isolated from a laboratory colony of codling moth in British Columbia, Canada is identical or very similar to the Mexican isolate of Cydia pomonella granulovirus (CpGV‐M). In addition to codling moth, the vims was found to cause mortality of secondary leafroller pests of North American orchards, including the fruit tree leafroller and the obliquebanded leafroller. A survey in apple growing regions of British Columbia indicates that 23% of the wild population of codling moth larvae carry CpGV.

Abundance of Parasitoids of Archips argyrospila (Lepidoptera: Tortricidae) in Louisiana

The fruittree leafroller, Archips argyrospila (Walker), was first observed feeding on baldcypress, Taxodium distichum (L. ) Richard, in 1983 in southern Louisiana. Since then, a prolonged epidemic has persisted in semi- and permanently flooded forested wetlands encompassing 100,000 ha. Species and abundance of parasitoids associated with fruittree leafroller on baldcypress were determined at 2 sites in Louisiana during 1994 and 1995, Six species of primary parasitoids were reared from the larvae and pupae of fruittree leafroller, Mortality by all parasitoid species for the combined larval and pupal stages in the 2 seasons was 22.8 and 13.6% at Bayou Pigeon and Norco, respectively, Itoplectis conquisitor (Say) (Hymenoptera: Ichneumonidae) was the most abundant parasitoid and Brachymeria ovata (Say) (Hymenoptera: Chalcidae) ranked second. The rate of parasitism by 1. conquisitor for both years averaged 13.8% at Bayou Pigeon and 8.4% at Norco. The eulophid Dimmockia incongrua (Ashmead) (Hymenoptera: Eulophidae) a hyperparasitoid of I. conquisitor. No parasitoids were reared from or found in dissections of egg masses collected in the 2-yr study. Thus, it appears that the absence of egg parasitism and the low levels of larval parasites are responsible in part for allowing populations of the fruittree leafroller to continue at epidemic levels in wetlands in Louisiana.

Geographic and Host-Associated Differentiation in the Fruittree Leafroller (Lepidoptera: Tortricidae)

The fruittree leafroller, Archips argyrospila (Walker), has recently reached out-break densities on a newly recorded host plant, baldcypress, Taxodium distichum (L.) Richard. We conducted a genetic analysis of the cypress population and one feeding on oaks in Louisiana. To obtain a geographic perspective on differentiation within the fruittree leafroller, we compared the Louisiana cypress population with a California oak population genetically and conducted cross-rearing studies on oak and cypress. A citrus population from California was also included for a host-associated perspective. Genetic data suggest the existence of three distinct taxa. One taxon feeds on oaks and citrus in California, one feeds on oaks in Louisiana, and a third feeds on baldcypress in Louisiana. Developmental cross-rearing studies indicate the cypress population is virtually unable to survive on Louisiana oaks, further supporting the existence of host-associated differentiation. Pheromone attraction studies conducted in Louisiana forests with California citrus and Louisiana cypress virgin females indicate California citrus females are not attractive to male fruittree leafrollers in cypress swamps. Differences in pheromonal response suggest evolutionary divergence in mating behavior on a geographic scale. Further studies are required to determine the degree of reproductive isolation between host associated and geographic populations, but genetic, developmental, and pheromonal studies suggest sibling species or host races, or both, exist.

California Small Plot Citrus Thrips Trials, 1994

Abstract Insecticides were evaluated in 2 fields at the University of California’s Lindcove Field Station near Exeter, California for control of citrus thrips (Field 12, 24 yr old ‘Atwood’ navel oranges; Field 14, 22 yr old Old Line navels). Pesticides were applied with a Bean hand-sprayer at 500 psi, outside coverage, approximately 200 gpa. Field 12 was divided into 4 replicate blocks of 52 trees and 12 treatments were applied with one replicate of each treatment assigned randomly to each block except a second replicate was assigned randomly to the control in 3 of the 4 blocks and the Admire treatment was excluded from one block. Each replicate was 4 contiguous trees. Field 14 was designed similarly with 4 blocks and 33 treatments with one 4-tree replicate assigned randomly to each treatment in each block. Citrus thrips infestation due to first and second instars was monitored in some of the treatments in Field 14 twice a wk for 6 wks after petal fall by examining 5 fruit randomly from each data tree (50 fruit per plot, 100 fruit per treatment in each field). Citrus thrips fruit scarring evaluations were taken in Oct, 1994 on all fruit on the exterior of data trees from knee to eye level. Typical scarring levels on outside fruit as sampled in this study are approximately twice as high as percent scarring of fruit sampled from the entire tree (inside fruit are less severely scarred). Scarring was rated as: (a) none, (b) slight (any citrus thrips scarring), or (c) severe (complete ring scar or extensive surface scarring at a level that would cause downgrading of fruit in a commercial operation). Economic scarring levels in a normal yr are about 5% severe scars. Ctirus cutworm and fruit tree leafroller levels were high in this block just prior to and after petal fall resulting in high levels of fruit drop. After assessing citrus thrips fruit scarring levels in Oct, any trees with less than 30 outside assessed fruit were excluded from the analysis (a total of 13 trees were excluded, 1—3 trees from each of 9 treatments).

Disruption of Pheromone Communication in Three Sympatric Leafroller (Lepidoptera: Tortricidae) Pests of Apple in British Columbia

Fruittree leafroller, Archips argyrospila (Walker), obliquebanded leafroller, Choristoneura rosaceana (Harris), and European leafroller Archips rosana (Robinson), all use Z11–14:OAc and E11–14:OAc as components of their species-specific pheromone blends. Small-plot experiments (0.09 ha) were conducted in the Okanagan Valley of British Columbia to evaluate the effects of atmospheric permeation with different concentrations of Z11–14:OAc and E11–14:OAc, applied in a ratio of 93:7, on pheromone communication of these sympatric species. The relative response of male moths to synthetic and natural pheromone-baited traps in pheromone-treated and untreated plots was used to measure disruption of pheromone communication. The pheromone-disruption blend was released by polyethylene tube-type dispensers applied at various densities. Catches of A. argyrospila in synthetic pheromone traps decreased by >92 and 97% when pheromone was applied at rates of 5–10 mg/h/ha and 20–40 mg/h/ha, respectively. Catches of A. argyrospila in virgin female-baited traps were reduced by 99% at pheromone application rates of 20–40 mg/h/ha. Catches of C. rosaceana and A. rosana in synthetic pheromone-baited traps decreased by 88–96% when the pheromone disruptant was applied at rates of 20–40 mg/h/ha. In pheromone-disrupted plots, more male A. argyrospila were caught in traps baited with pheromone blends of C. rosaceana and A. rosana containing a higher percentage of Z11–14:OAc than the reported pheromone blend of A. argyrospila. These results suggest an alteration of the normal pheromonal response of A. argyrospila on exposure to a high concentration of Z11–14:OAc for a sustained time.

Fruittree Leafroller, Archips argyrospila (Walker) (Lepidoptera: Tortricidae), Performance as Influenced by Host Foliage Type

Performance of early and late instars of the fruittree leafroller, Archips argyrospila (Walker), was quantified from bioassays using previously uninfested foliage of baldcypress (Taxodium distichum L.) and two other potential hosts. Initial survival and host preference tests indicated that open morphology baldcypress foliage was more suitable for first instars than either appressed morphology baldcypress or pondcypress. Growth, development, and host utilization indices, based on rearing of late instars, revealed that open morphology baldcypress foliage was most susceptible to defoliation. Late-instar bioassays also indicated that pondcypress foliage was the least susceptible cypress foliage type tested, due to mechanism(s) triggering early termination of larval development. The appressed morphology baldcypress foliage was of moderate susceptibility, apparently because of foliage characteristics deterring its consumption. Shumard oak, Quercus shumardii Buckl., and sweet citrus, Citrus siniensis (L.), did not support early-instar survival or late-instar development and, thus, appear to preclude the threat of fruittree leafroller defoliation in the Gulf States. The results indicated that there is a high potential for fruittree leafrollers to infest areas where pondcypress occurs.

Sex pheromone components of the fruit-tree leaf roller,Archips argyrospilus (Walker) (Lepidoptera: Tortricidae), in British Columbia

In field experiments in the Okanagan Valley, British Columbia, the pheromone blend of (11Z)-tetradecen-1-ol acetate (Z11-14:OAc), (11E)-tetradecen-1-ol acetate (E 11-14:OAc), (9Z)-tetradecen-1-ol acetate (Z9-14:OAc) and dodecan-1-ol acetate (12: OAc) at a 100∶64∶2∶1 ratio (western FTLR blend) attracted significantly more male fruit-tree leaf roller (FTLR),Archips argyrospilus (Walker), than did the previously reported four-component blend and modifications thereof. Addition of (11Z)-tetradecen-1-ol (Z11-14:OH) to the western FTLR blend in a ratio of 4% relative toZ11-14: OAc further significantly enhanced attraction. Compounds were identified and their ratio determined by coupled gas chromatographic-electroantennographic (GC-EAD) and coupled GC-mass spectrometric analyses of female FTLR pheromone gland extracts and by retention index calculations of candidate pheromone components. Determination and use of geographically specific pheromonal blends may be required for optimal, semiochemical-based biorational control of FTLR and other lepidopteran orchard pests.

Relationships Between Patterns of Defoliation by the Fruittree Leafroller (Lepidoptera: Tortricidae) and Foliage Morphology of Baldcypress in Forested Wetlands of Louisiana

Baldcypress, Taxodium distichum (L.) Richard, has been threatened recently by a new insect herbivore, the fruittree leafroller, Archips argyrospila (Walker) (Lepidoptera: Tortricidae). Baldcypress foliage varies from long-leaved, open-faced branchlets with leaves arranged in two-ranked fashion to short-leaved, appressed, imbricate branchlets. Field surveys revealed that the tallest trees contained 72 – 85% appressed foliage, whereas intermediate and small-sized trees contained 55–92% open type foliage. Over a three-year period, open morphology trees repeatedly exhibited significantly higher levels of defoliation (percentage of crown loss) by the fruittree leafroller, compared with appressed morphology trees. There was no ovipositional preference (number of egg masses) associated with morphology type. Differences in defoliation levels, therefore, were attributed to morphologically related influences on foliage suitability for larval stages.

TEMPERATURE-DEPENDENT DEVELOPMENT AND PREDICTION OF HATCH OF OVERWINTERED EGGS OF THE FRUITTREE LEAFROLLER, ARCHIPS ARGYROSPILUS (WALKER) (LEPIDOPTERA: TORTRICIDAE)

AbstractThermal responses and temperature-dependent development of laboratory- and field-overwintered eggs of the fruittree leafroller, Archips argyrospilus (Walker), were described using data from constant-temperature laboratory experiments. The time required for completion of hatch of overwintering eggs declined throughout winter until the end of January, after which increasing exposure to natural or artificial cold conditions had minimal effect on median hatching time. There was little year to year variation in response to cold treatments, and thus it was concluded that diapause is terminated by 1 February. Time to hatch decreased with increasing temperature. Distributions of hatch times were near normal, with mean and median development times similar at any given temperature. Development time (days ± SD) at a mean temperature of 20 °C was similar under constant (10.7 ± 1.1) and fluctuating (9.1 ± 1.4) temperature regimes. A nonlinear, six-parameter, biophysical model, fitted (r2 = 0.99) to median hatching rates at 11 temperatures (0.5–30 °C) indicated development was nonlinear below 10 °C, increased linearly between 10 and 25 °C, was maximal at 27.5 °C, and decreased above 27.5 °C. The lower developmental threshold (± SE), estimated to be 4.95 ± 0.54 °C by linear regression (r2 = 0.98) and the x-intercept method, was used to construct a degree-day (DD) model for predicting egg hatch. Median egg development required 154 DD above 4.95 °C. Observed median egg hatch in two different field sites and years was within ± 3 days of the predicted date, using max–min air temperatures, a base temperature of 5 °C, and a starting date of 1 February for accumulating DD. This model should prove useful for scheduling management actions against fruittree leafroller on apples and pears.

Seasonal Occurrence of Calleida viridipennis (Say) and Plochionus timidus Haldeman (Coleoptera: Carabidae), Predators of the Fruittree Leafroller, Archips argyrospila (Walker), in Louisiana

Calleida viridipennis (Say) and Plochionus timidus Haldeman overwinter as adults under the bark of baldcypress, Taxodium distichum (L.) Richard, (diam. at breast height (DBH) > 30 cm) and black willow, Salix nigra Marsh, (DBH > 15 cm) at a height more than 40 cm above the water level in forested wetlands. Both carabid species were found to be spring breeders, with adults surviving approximately one year. Adults of both species emerged from overwintering in late February or early March when the fruittree leafroller, Archips argyrospila (Walker), caterpillars were active on baldcypress. Carabid eggs were distributed among foliage and host webs from mid- or late-March to late-September with larvae occurring from late-March to early or mid-October. Both carabid species were found to be associated with the fall webworm, Hyphantria cunea (Drury), after the univoltine fruittree leafroller larvae completed their development.

Larval performance of two leafroller species on known and potential hosts

AbstractTwo univoltine leafroller species, Archips argyrospila Walker and Archips rosana L., were reared from eclosion to adulthood on known or potential host plants. Both species were able to complete development on eight of the ten plants tested, the exceptions being apricot and peach. Rates of development differed among hosts, and indicated a range of host suitability. Differences in female pupal weights were apparent following the different rearing treatments, but these did not correlate with subsequent female fecundity. When development was compared between the two leafroller species, A. rosana had higher survivorship, more rapid development and higher female fecundity than did A. argyrospila, regardless of host. These findings indicate that A. rosana may successfully exploit a wider host range than does A. argyrospila. Comparisons of survivorship and developmental rates among hosts for each species of leafroller suggest that both species may have the potential for host‐range expansion.

Monitoring Azinphosmethyl Resistance in Archips agyrospila (Lepidoptera: Tortricidae) Populations

Azinphosmethyl was applied topically to the dorsal thorax of male fruittree leafroller moths, Archips agyrospila (Walker), caught in pheromone traps from 1986 to 1988 to test the tolerance of this pest within individual orchards. The LC50’s estimated with this technique generally reflected the control problems experienced in the individual orchards and were correlated with the tolerance exhibited by neonate fruit tree leafrollers fed diet containing azinphosmethyl in laboratory bioassays. However, high control mortality, and a lack of understanding of behavior in the adult males in response to pheromones and the natural variation in mortality, decrease the reliability of this technique in assessing the azinphosmethyl resistance of individual fruit tree leafroller orchard populations.

Insect herbivores of a bald-cypress/tupelo ecosystem

The forest tent caterpillar, Malacosoma disstria Hubner, and the fruit-tree leafroller, Archips argyprospila (Walker), are the two dominant insect herbivores affectinf Louisiana's forested wetlands. The lack of tree species diversity and the paucity of natural enemies has resulted in continuous epidemics of these two herbivores. The resultant effects have been severe radial-growth losses of tupelo, Nyssa aquatica L., caused by the forest tent caterpillar, and growth reduction, dieback, and scattered mortality of bald cypress, Taxodium distichum L., by a relatively new insect pest of this tree species, the fruit-tree leafroller.

Biology and Mortality Agents of the Fruittree Leafroller (Lepidoptera: Tortricidae), on Baldcypress in Louisiana

The fruittree leafroller, Archips argyrospila (Walker), recently has been found feeding on a new host, baldcypress (Taxodium distichum (L.) Rich.) at outbreak levels in Louisiana. The general biology of A. argyrospila and the impact of its parasitoids, predators, and hyperparasitoids found in infestation areas in and near the Atchafalaya Basin in Louisiana are described. The hymenopteran parasitoid, Itoplectis conquisitor (Say), caused the greatest amount of pupal parasitism. Two carabids, Plochionus timidis Haldeman and Calleida viridipennis Say, were found to be important predators of larvae and pupae.