Choristoneura Rosaceana Research Articles

Comparative Programs for Arthropod, Disease and Weed Management in New York Organic Apples.

Organic apple production in the eastern US is small and is mostly based on existing varieties, which are susceptible to scab, and rootstocks, which are susceptible to fire blight. This requires numerous sprays per year of various pesticides to produce acceptable fruit. From 2014 to 2016, we tested different arthropod, disease and weed management programs in an advanced tall spindle high-density production system that included disease-resistant cultivars and rootstocks, in an organic research planting of apples in Geneva, New York. Arthropod and disease management regimens were characterized as Advanced Organic, Minimal Organic, or Untreated Control. Results varied by year and variety, but, in general, the Advanced program was more effective than the Minimal program in preventing damage from internal-feeding Lepidoptera, plum curculio, and obliquebanded leafroller, and less effective than the Minimal program against damage by foliar insects. Both organic programs provided comparable control of sooty blotch, cedar apple rust, and fire blight, with some variability across cultivars and years. The advanced selection CC1009 and Modi seemed to possess complete resistance to cedar apple rust, while Pristine had partial resistance. For weed control, bark chip mulch, organic soap sprays, and limonene sprays tended to be most effective, while mechanical tillage and flame weeding had lower success.

Predation Capability and Functional Response ofChrysoperla carneatoChoristoneura rosaceanaunder Laboratory Conditions

Functional response of third-instar larvae of green lacewing, Chrysoperla carnea (Stephen) (Neuroptera: Chrysopidae), to four densities of single-instar larvae of the five instars of obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), was evaluated at 25 ± 1°C in a laboratory. The aims were to determine the type and other characteristics of functional response including predatory capacity of green lacewing for possible use in augmentative biological control in apple (Malus × domestica Borkh; Rosales: Rosaceae) orchards where obliquebanded leafroller was recently introduced in Mexico. Abundance of the pest increased rapidly, causing significant foliar damage and some fruit blemish. Third-instar green lacewing larvae based on logistic regression analysis showed Type II functional response to four densities of single-instar larvae of obliquebanded leafroller. Among the five instars of prey, the largest average number consumed per green lacewing predator was a relative density of four second-instar larvae at a rate of 1.93 in 24 hours. Also, substantial average consumption was by two third-instar prey larvae per predator whereby an average of 1.5 third-instar obliquebanded leafrollers were consumed per third-instar green lacewing in 24 hours. The third-instar predator captured and consumed third-instar prey larvae in the shortest handling time (h), i.e., only 6.46 minutes, whereas the handling times for the other instars ranged from 23.48 minutes for the fifth instar to 31.56 minutes for the fourth instar. However, attack coefficients (a) of green lacewings were slightly greater for third- and fourth-instar prey larvae, with 0.19 hour (11.4 minutes) and 0.15 hour (9.0 minutes) until the first attack, respectively, compared to 0.09–0.11 hour (5.4–6.6 minutes) until the first attack for the other instars. Results indicated that the green lacewing could be considered a prospective candidate for use as a biological control agent against lepidopteran leafrollers.

Caterpillar-Induced Plant Volatiles Attract Adult Tortricidae

Binary and ternary combinations of volatile organic compounds identified earlier from caterpillar-infested apple foliage caught more than one thousand individuals of both sexes of several adult tortricid leafroller species in several days of trials conducted in apple orchards in southern British Columbia. A series of combinations with phenylacetonitrile, benzyl alcohol, and/or 2-phenylethanol and acetic acid enabled substantial catches of both sexes of eye-spotted budmoth, Spilonota ocellana, oblique-banded leafroller, Choristoneura rosaceana and three-lined leafroller, Pandemis limitata. These findings suggest that new monitoring aides can be developed to seasonally track populations, enabling practical applications in surveillance of female leafroller populations for the first time. It may also be possible to develop suppression tools based on combinations of kairomone compounds originally identified from leafroller larval-damaged apple trees, given the level of attraction. The discovery of these adult tortricid attractants (aromatic compounds plus acetic acid) raises new ecological questions about evolved direct plant defences against herbivores. Larval feeding-induced attraction of adult herbivores produces signals that are potentially harmful to the plant by increasing herbivory in the same family and probably feeding guild, but evidence for effects on plant fitness is needed.

Impact of exclusion netting row covers on arthropod presence and crop damage to ‘Honeycrisp’ apple trees in North America: A five-year study

Exclusion nets have been used successfully in France against codling moth Cydia pomonella (L.) since the early 2000s. Such a system has been adapted for North American conditions and was tested in an experimental apple orchard (‘Honeycrisp’) in southern Quebec, Canada from 2012 to 2016. Evaluation of insect and disease damage, as well as physical and physiological damage, was made in complete exclusion plots—in which the soil is also excluded—and in unnetted control plots. The exclusion system proved to be an effective protection device for the vast majority of key pests of apple fruit in most years. Damage from key insect pests such as the apple maggot Rhagoletis pomonella (Walsh), the tarnished plant bug Lygus lineolaris (Palisot de Beauvois) and the codling moth was significantly lower in netted plots than in unnetted plots. However, obliquebanded leafroller Choristoneura rosaceana (Harris) damage increased over the years to the point of being significantly more important in netted plots in 2015. Minimal or non-significant effects were observed on smaller, foliar pests, while highly significant protection effects were recorded for abiotic damage from frost and hail events that occurred during the study. Nets showed a significant protective effect on diseases such as apple scab Venturia inaequalis (Cooke) G. Wint., Gymnosporangium spp. rusts, and sooty blotch and flyspeck (SBFS) complex, when these were present in our plots.

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

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

Excised Leaf Bioassay: Phenotypic Expression of Natural Resistance in Apple against the Obliquebanded Leafroller

Different approaches were assessed in the development of a bioassay method that would provide data necessary to evaluate resistance of apple genotypes to the obliquebanded leafroller (OBLR) Choristoneura rosaceana (Harris). A leaf disc method used to evaluate the impact of pesticides on leafrollers resulted in high levels of leaf-abandonment of first and second instar larvae. Inserting leaf petioles into water soaked Oasis foam resulted in a significant reduction in overall leaf weight and diminished the appearance of leaf quality. When leaf petioles were inserted into water-filled Eppendorf vials, leaf weight increased and overall leaf quality appeared to be good. We opted to adopt this latter whole-leaf bioassay method, which though very time consuming, provided a robust assessment of OBLR life history parameters against different apple genotypes. Across all apple genotypes evaluated, male larvae developed faster than females to pupation as well as to adulthood, while females developed faster as pupae and were heavier than male pupae. OBLR larvae reared on leaves from different apple genotypes displayed significant variability in development time, pupal weight, larval survivorship, and number of offspring produced. We utilized three indices to characterize host acceptance, sub-lethal effects, and lethal effects of OBLR to apple genotypes. Our results indicated that ‘Lady’, ‘Viking’, and ‘Northern Spy’ show some of the highest levels of resistance against OBLR, while ‘Granny Smith’ was quite susceptible to OBLR and could be used in future studies identifying apple genotypes with relative resistance to OBLR.

Caterpillar-induced plant volatiles attract conspecific adults in nature.

Plants release volatiles in response to caterpillar feeding that attract natural enemies of the herbivores, a tri-trophic interaction which has been considered an indirect plant defence against herbivores. The caterpillar-induced plant volatiles have been reported to repel or attract conspecific adult herbivores. To date however, no volatile signals that either repel or attract conspecific adults under field conditions have been chemically identified. Apple seedlings uniquely released seven compounds including acetic acid, acetic anhydride, benzyl alcohol, benzyl nitrile, indole, 2-phenylethanol, and (E)-nerolidol only when infested by larvae of the light brown apple moth, Epiphyas postvittana. In field tests in New Zealand, a blend of two of these, benzyl nitrile and acetic acid, attracted a large number of conspecific male and female adult moths. In North America, male and female adults of the tortricid, oblique-banded leafroller, Choristoneura rosaceana, were most attracted to a blend of 2-phenylethanol and acetic acid. Both sexes of the eye-spotted bud moth, Spilonota ocellana, were highly attracted to a blend of benzyl nitrile and acetic acid. This study provides the first identification of caterpillar-induced plant volatiles that attract conspecific adult herbivores under natural conditions, challenging the expectation of herbivore avoidance of these induced volatiles.

Sequence variation determining stereochemistry of a Δ11 desaturase active in moth sex pheromone biosynthesis

A Δ11 desaturase from the oblique banded leaf roller moth Choristoneura rosaceana takes the saturated myristic acid and produces a mixture of (E)-11-tetradecenoate and (Z)-11-tetradecenoate with an excess of the Z isomer (35:65). A desaturase from the spotted fireworm moth Choristoneura parallela also operates on myristic acid substrate but produces almost pure (E)-11-tetradecenoate. The two desaturases share 92% amino acid identity and 97% amino acid similarity. There are 24 amino acids differing between these two desaturases. We constructed mutations at all of these positions to pinpoint the sites that determine the product stereochemistry. We demonstrated with a yeast functional assay that one amino acid at the cytosolic carboxyl terminus of the protein (258E) is critical for the Z activity of the C. rosaceana desaturase. Mutating the glutamic acid (E) into aspartic acid (D) transforms the C. rosaceana enzyme into a desaturase with C. parallela-like activity, whereas the reciprocal mutation of the C. parallela desaturase transformed it into an enzyme producing an intermediate 64:36 E/Z product ratio. We discuss the causal link between this amino acid change and the stereochemical properties of the desaturase and the role of desaturase mutations in pheromone evolution.

Effect of Over-Tree Evaporative Cooling in Orchards on Microclimate and Accuracy of Insect Model Predictions.

Orchard design and management practices can alter microclimate and, thus, potentially affect insect development. If sufficiently large, these deviations in microclimate can compromise the accuracy of phenology model predictions used in integrated pest management (IPM) programs. Sunburn causes considerable damage in the Pacific Northwest, United States, apple-producing region. Common prevention strategies include the use of fruit surface protectants, evaporative cooling (EC), or both. This study focused on the effect of EC on ambient temperatures and model predictions for four insects (codling moth, Cydia pomonella L.; Lacanobia fruitworm, Lacanobia subjuncta Grote and Robinson; oblique-banded leafroller, Choristoneura rosaceana Harris; and Pandemis leafroller, Pandemis pyrusana Kearfott). Over-tree EC was applied in July and August when daily maximum temperatures were predicted to be ≥30°C between 1200-1700 hours (15/15 min on/off interval) in 2011 and between 1200-1800 hours (15/10 min on/off interval, or continuous on) in 2012. Control plots were sprayed once with kaolin clay in early July. During interval and continuous cooling, over-tree cooling reduced average afternoon temperatures compared with the kaolin treatment by 2.1-3.2°C. Compared with kaolin-treated controls, codling moth and Lacanobia fruitworm egg hatch in EC plots was predicted to occur up to 2 d and 1 d late, respectively. The presence of fourth-instar oblique-banded leafroller and Pandemis leafroller was predicted to occur up to 2 d and 1 d earlier in EC plots, respectively. These differences in model predictions were negligible, suggesting that no adjustments in pest management timing are needed when using EC in high-density apple orchards.

A convenient diagnostic polymerase chain reaction method for identifying codling moth Cydia pomonella (Lepidoptera: Tortricidae) among tortricid pests in cherries imported from western North America

To assist with plant quarantine inspections, we developed a specific primer set for use in a diagnostic polymerase chain reaction method of distinguishing the codling moth Cydia pomonella (L.). from other tortricid pests in cherries imported from western North America: Archips argyrospila (Walker), A. rosana (L.), Argyrotaenia franciscana (Walsingham), Cacoecimorpha pronubana (Hubner), Choristoneura rosaceana (Harris), Epiphyas postvittana (Walker), Grapholita molesta (Busck), G. packardi Zeller, G. prunivora (Walsh), Pandemis pyrusana (Kearfott), and Spilonota ocellana (Denis and Schiffermuller). A 472-bp fragment of mitochondrial cytochrome oxidase subunit I (COI) gene was sequenced in 3–18 specimens of each species except for A. rosana and P. pyrusana. C. pomonella demonstrated consistent and diagnostic differences from other species in two regions of the COI gene from which forward and reverse primers were designed to amplify a 326-bp segment. The primer sets were used to selectively amplify DNA from specimens obtained from various geographic origins to check for C. pomonella. This method enabled immediate and accurate identification of C. pomonella, and thus provides an effective tool for nations concerned about possible invasions of this pest.

Brood Guarding by an Adult Parasitoid Reduces Cannibalism of Parasitoid-Attacked Conspecifics by a Caterpillar Host

Adult female bethylid parasitoids (Hymenoptera: Bethylidae) commonly guard their offspring until they develop into later immature stages to protect them from competing parasitoids and predators. Another possible mortality factor is from caterpillar larvae that cannibalize parasitized conspecific larvae. This study determined the effect of brood guarding on the occurrence of host cannibalism by using a brood guarding bethylid parasitoid Goniozus legneri and a non-guarding braconid parasitoid Habrobracon gelechiae (Hymenoptera: Braconidae), both are gregarious ectoprasitoids that attack the obliquebanded leafroller Choristoneura rosaceana (Lepidoptera: Tortricidae). When a C. rosaceana larva parasitized by G. legneri was presented to a live conspecific larva, the frequency of cannibalism on the parasitized conspecific was lower in the presence than in the absence of a guarding female G. legneri. In contrast, when a C. rosaceana larva parasitized by H. gelechiae was presented to a live conspecific larva, the presence or absence of H. gelechiae did not affect cannibalism frequency. Cannibals did not gain a fitness advantage in terms of larval survival, developmental time, or body mass of developed pupae; therefore, cannibalism by the host larva may be a group defense against increased parasitism in subsequent population generations. We suggest that brood guarding by parasitoids can act as a broad defense strategy to protect offspring from the cannibalism of parasitized conspecifics by the host larvae.

Use of glacial acetic acid to enhance bisexual monitoring of tortricid pests with kairomone lures in pome fruits.

Studies were conducted to assess glacial acetic acid (GAA) with various host plant volatiles (HPVs) and the sex pheromone, (E,E)-8, 10-dodecadien-1-ol, of codling moth, Cydia pomonella (L), as lures in traps for tortricid pests that often co-occur in tree fruits in the western United States. In addition to codling moth, field trapping studies were conducted with oriental fruit moth, Grapholita molesta (Busck), obliquebanded leafroller Choristoneura rosaceana (Harris), the leafroller Pandemis pyrusana Kearfott, and the eyespotted budmoth, Spilonota ocellana (Denis and Schiffermüller). HPVs included ethyl (E,Z)-2,4-decadienoate (pear ester), (E)-4,8-dimethyl-1,3,7-nonatriene, butyl hexanoate, (E)-β-ocimene, (E)-β-farnesene, and farnesol. Three types of GAA co-lures differing in a 10-fold range in weekly evaporation rates were tested. The evaporation rate of GAA co-lures was an important factor affecting moth catches. The highest rate tested captured fewer codling moth but more leafrollers and eyespotted budmoth. GAA co-lures caught both sexes of each species. The field life of butyl hexanoate and (E)-β-ocimene lures were much shorter than pear ester or sex pheromone lures. Adding GAA to pear ester or to (E)-β-ocimene significantly increased the catches of only codling moth or oriental fruit moth, respectively. Combining pear ester or (E)-β-ocimene with GAA did not affect the catch of either species compared with the single more attractive HPV. Adding HPVs to GAA did not increase the catches of either leafroller species or eyespotted budmoth. Traps baited with pear ester, sex pheromone, and GAA for monitoring codling moth were also effective in classifying pest pressure of both leafroller species within orchards.

Trunk injection: An alternative technique for pesticide delivery in apples

Field studies, laboratory bioassays, and residue profile analysis were used to determine the seasonal effectiveness of trunk injected pesticides against key apple disease and insect pests. Insecticides formulated for trunk injection, imidacloprid (Ima-jet™), rynaxypyr (XCL-r8™), and emamectin benzoate (TREE-age™) were injected into semi-dwarf Empire apple trees Malus domestica (Borkhausen) and evaluated for a wide range of insect pests. The fungicide compounds, propiconazole (Alamo®), phosphites (Phospho-jet), and penthiopyrad (Fontelis™), were injected into semi-dwarf MacIntosh (RedMax) apple trees M.domestica (Borkhausen) for control of apple scab fungus, Venturia inaequalis (Cooke). After the original single injection, imidacloprid was highly effective in controlling piercing and sucking pests such as the potato leafhopper, Empoasca fabae (Harris), and aphids (Aphididae), and emamectin benzoate was highly effective in controlling the oblique banded leaf roller, Choristoneura rosaceana (Harris), and potato leafhopper, E. fabae (Harris), and rynaxypyr was highly effective in controlling Oriental fruit moth, Grapholita molesta (Busck), and leafrollers all for two growing seasons. The residue profiles for insecticides showed that vascular delivery was predominantly to foliage, with fruit residues far below the EPA maximum residue limits (MRLs), and low to no residues detected in apple flower parts. Phosphites provided significant levels of apple scab control over two seasons for the single injection after the foliage recovered from the phytotoxicity damage in the first season. Propiconazole and penthiopyrad showed limited effectiveness for the control of apple scab. The residue profiles for fungicides showed phosphites to be delivered primarily to foliage, but inconsistent foliar residue levels for the other two compounds suggests possible incompatibilities may be responsible for poor product performance. These incompatibilities may include molecular or chemical properties. For example, on the molecular level such as the molecular size too large to fit through vascular tissue and chemical properties such as the viscosity of the compound resulting in poor translocation or pH.

Female Moth Calling and Flight Behavior Are Altered Hours Following Pheromone Autodetection: Possible Implications for Practical Management with Mating Disruption.

Female moths are known to detect their own sex pheromone—a phenomenon called “autodetection”. Autodetection has various effects on female moth behavior, including altering natural circadian rhythm of calling behavior, inducing flight, and in some cases causing aggregations of conspecifics. A proposed hypothesis for the possible evolutionary benefits of autodetection is its possible role as a spacing mechanism to reduce female-female competition. Here, we explore autodetection in two species of tortricids (Grapholita molesta (Busck) and Choristoneura rosaceana (Harris)). We find that females of both species not only “autodetect,” but that learning (change in behavior following experience) occurs, which affects behavior for at least 24 hours after pheromone pre-exposure. Specifically, female calling in both species is advanced at least 24 hours, but not 5 days, following pheromone pre-exposure. Also, the propensity of female moths to initiate flight and the duration of flights, as quantified by a laboratory flight mill, were advanced in pre-exposed females as compared with controls. Pheromone pre-exposure did not affect the proportion of mated moths when they were confined with males in small enclosures over 24 hours in laboratory assays. We discuss the possible implications of these results with respect to management of these known pest species with the use of pheromone-based mating disruption.

Cannibalism of parasitoid‐attacked conspecifics in a non‐carnivorous caterpillar

AbstractCannibalism, the killing and consumption of conspecifics, can even occur in insect species typically considered to be non‐carnivorous. Of particular interest is the cannibalism of parasitoid‐attacked conspecifics, which could reduce parasitism levels in subsequent generations for that conspecific population. This study reports on the occurrence and some of the consequences of cannibalism in parasitoid‐attacked obliquebanded leafroller,Choristoneura rosaceana(Harris) (Lepidoptera:Tortricidae). We show that larvae ofC. rosaceana, which is considered to be an herbivorous caterpillar species, did not prey upon live conspecifics, but readily consumed conspecifics attacked byHabrobracon gelechiaeAshmead (Hymenoptera:Braconidae). Further examination found thatC. rosaceanalarvae feeding on parasitoid‐attacked conspecifics, since their fourth instar, suffered a higher mortality and reduction in body size than those fed on plant material only. The cannibalism of attacked conspecifics did not appear to offer any nutrient benefits for the cannibal. To our best knowledge, this is the first empirical example of the occurrence and some of the consequences of cannibalism by a non‐carnivorous insect on its parasitoid‐attacked conspecifics. We discuss the adaptive significance of such cannibalism on parasitoid‐attacked conspecifics with respect to a trans‐generational fitness gain for the population through the killing of the parasitoids, thereby reducing parasitism in subsequent generations.

Tri-trophic movement of carotenoid pigments from host plant to the parasitoid of a caterpillar

Insect parasitoids normally produce white colored eggs. Habrobracon gelechiae (Hymenoptera: Braconidae) is a gregarious ectoparasitoid of various caterpillars. We found that adult female H. gelechiae lays yellow colored eggs when its larvae developed from host larvae of Choristoneura rosaceana and Epiphyas postvittana (both Lepidoptera: Tortricidae) that were fed green plant leaves, but white colored eggs when these same host larvae species were fed non-plant diets. This study investigated the causes of egg color in H. gelechiae and the possible consequences in terms of parasitoid fitness resulting from differential egg color. Using high-performance liquid chromatography we demonstrated that the yellow coloration resulted from the uptake of carotenoid plant pigments (mainly lutein and β-carotene) that were initially ingested by the caterpillar larvae from plant leaves, later absorbed by the parasitoid larvae (F0) feeding on the host and carried over to the adult parasitoids, and finally translocated to the eggs (F1) of the parasitoids. The amount of plant pigments consumed by the parasitoid larvae (F0) affected the intensity of the yellow color of the parasitoid’s eggs (F1). Similarly, egg color was affected by the adult female parasitoids lifetime egg production and deposition rate. Further tests suggest that the observed differences in egg color did not have a genetic basis and did not affect egg viability or fitness. To our best knowledge, this is the first report of a tri-trophic and multi-stage translocation of carotenoid plant pigments in parasitoids. We discuss possible evolutionary significance and putative functions of the absorption of plant pigments by parasitoid species.

Transovarial transmission of novaluron in Choristoneura rosaceana (Lepidoptera: Tortricidae)

AbstractThe obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), has become a significant pest of tree fruit production in North America within the past 25 years. Control of the OBLR has historically relied upon broad-spectrum insecticides like organophosphates, carbamates, and pyrethroids. However, with evidence of resistance development, newer chemistries have been developed to combat this pest. The effects of novaluron, a chitin synthesis inhibitor, were studied to determine if reduced egg hatch occurs after exposure to adults. The transovarial effects of this compound were tested through laboratory bioassays, looking at decreased egg hatch and also presence of novaluron in egg masses following adult exposure. Results from the study demonstrated a decrease in egg hatch after adult exposure. Analysis of egg mass using HPLC also demonstrated novaluron present in the eggs laid by treated adults. Along with the direct ovicidal and larvicidal properties of novaluron, this transovarial activity provides an important contribution to the overall control seen in the field.

Age-based mating success in the codling moth,Cydia pomonella, and the obliquebanded leafroller,Choristoneura rosaceana

In this study, the passage of spermatophores was examined between 1-day-old males mated in no-choice situations with females 0, 2, 4, or 6 days old and the converse for both the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), and the obliquebanded leafroller, Choristoneura rosaceana (Harris). For C. pomonella, female age had no effect on the passage of spermatophores from males, and only 6-day-old female C. rosaceana had reduced spermatophore number. The ages of moths at the time of mating had a greater effect on males, with C. pomonella males older than 2 days showing significant reductions in the ability to successfully pass a spermatophore to 1-day-old females. For C. rosaceana, 2- and 6-day-old males were significantly less likely to pass a spermatophore, but reduced transfer from 4-day-old males did not reach statistical significance. Wind-tunnel assays were used to evaluate the ability of 1- or 4-day-old males to fly upwind and successfully contact a young calling female. Four-day-old males were more likely to initiate flight upwind, but were less efficient at finding and contacting the females than younger males. This study suggests that evaluation of multiple components of the mating process are required to understand the effect of age at the time of mating on population dynamics of these moths.

Parasitoid complex and bionomics ofApanteles polychrosidis(Hymenoptera: Braconidae) on the ash leaf-cone roller (Lepidoptera: Gracillariidae)

AbstractThe ash leaf-cone roller,Caloptilia fraxinella(Ely) (Lepidoptera: Gracillariidae) is an introduced leaf-mining moth of horticultural ash trees (FraxinusLinnaeus; Oleaceae) in Western Canadian Prairie cities. Here, we identify the dominant parasitoid of this leaf-mining moth asApanteles polychrosidisVierek (Hymenoptera: Braconidae) and document its emergence pattern, courtship, mating, and host acceptance behaviours.Apanteles polychrosidisadult emergence is protandrous and mating occurs soon after female emergence. MaleA. polychrosidiscan mate multiple times in short sequence with a mean copulation time of 49 seconds. It is likely thatA. polychrosidisoverwinters in an alternate larval host, after emergence fromC. fraxinella. Mated femaleA. polychrosidisreadily parasitise an alternate host, the obliquebanded leafroller (Choristoneura rosaceana(Harris); Lepidoptera: Tortricidae), known to overwinter as larvae. Through rearingC. fraxinellapupae, we describe the remainder of the parasitoid complex ofC. fraxinella, in order of parasitism rate, asDiadegmaFörster (nearDiadegmafenestrale(Holmgren)) (Hymenoptera: Ichneumonidae), threeSympiesisFörster species (Hymenoptera: Eulophidae) (Sympiesissericeicornis(Nees von Esenbeck), one nearSympiesisviridula(Thomson) and one unknown species), andPteromalus phycidis(Ashmead) (Hymenoptera: Pteromalidae) and show that severalSympiesisspecies can be hyperparasitic onA. polychrosidis.Caloptilia fraxinelladensity within the tree canopy is highest in the lower canopy. Host density and abiotic factors such as temperature and light intensity do not influence the within-canopy distribution of most parasitoids exceptSympiesisspecies, which preferred the northern canopy.

Biology and Potential Host Range of Pediobius ni (Hymenoptera: Eulophidae) as a Novel Resident Parasitoid of Light Brown Apple Moth (Lepidoptera: Tortricidae) in California

Abstract Pediobius ni Peck (Hymenoptera: Eulophidae) is a eulophid parasitoid indigenous to North America that was found attacking the invasive light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), in California. We investigated host age suitability, fecundity, and temperature-dependent developmental time for P. ni as a parasitoid of E. postvittana. Parasitoid offspring survival was higher on E. postvittana presented as prepupa or young pupa (<3 d old) than older pupa (>3d old), and P. ni would not attack mature E. postvittana larva. Parasitoid developmental time increased with advanced host age. At 24°C, P. ni parasitized 6.8 ± 0.7 hosts, and produced 119.5 ± 16.8 offspring during a 21.5 2± 3.0 d adult lifetime when provided food and host pupae. The developmental rate of P.ni was a positive linear relationship between 15–28°C, but it failed to develop at constant temperatures >29°C. The estimated lower developmental threshold is 13.0°C, and degree-day requirements (DD) are 278 DD. As a comparison of host species suitability, P.ni was tested with obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae); navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae); omnivorous leafroller, Platynota stultana Walsingham (Lepidoptera: Tortricidae); orange tortrix, Argyrotaenia franciscana (Walsingham) (Lepidoptera: Tortricidae); and peach twig borer, Anarsia lineatella Zeller (Lepidoptera: Gelechiidae). The parasitoid readily attacked all tested host species; percentage parasitism was lower on A. lineatella than on A. transitella, P. sultana, and C. rosaceana, but similar among the other tested species. Clutch size generally increased with host size, but percentage adult emergence and sex ratio was not affected by host species. Exposure of hosts to multiple P.ni increased the numbers of emerged wasps per parasitized host without obvious costs to offspring fitness.