Microencapsulated pear ester enhances insecticide efficacy in walnuts for codling moth (Lepidoptera: Tortricidae) and navel orangeworm (Lepidoptera: Pyralidae)

The efficacy of combining insecticides with a microencapsulated formulation of ethyl (2E,4Z) -2,4-decadienoate (pear ester, PE-MEC) was evaluated in walnuts, Juglans regia L., for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), and navel orangeworm, Amyelois transitella Walker (Lepidoptera, Pyralidae). Two types of studies were conducted to compare the use of insecticides with and without PE-MEC. In the first study, PE-MEC in combination with reduced rates of insecticides, including chlorpyrifos, phosmet, methoxyfenozide, and codling moth granulovirus were evaluated in single tree replicates. PE-MEC was tested at one to three rates (0.6, 1.8, and 4.4 g active ingredient ha(-1)) with each insecticide. In the second study, seasonal programs including sprays of esfenvalerate, chlorpyrifos, and ethyl parathion at full rates were evaluated in replicated two ha blocks. Significant reductions in nut injury occurred in the single-tree trial with treatments of PE-MEC plus insecticide compared with the insecticides used alone against both pest species; except with methoxyfenozide for navel orangeworm. Similarly, nut injury in the large plots was significantly reduced with the addition of PE-MEC, except for navel orangeworm in one of the two studies. These results suggest that adding pear ester as a microencapsulated spray can improve the efficacy of a range of insecticides for two key pests and foster the development of integrated pest management tactics with reduced insecticide use in walnut.     

The Role of Formulation Additives in Increasing the Potency of Cydia pomonella Granulovirus for Codling Moth Larvae,in Laboratory and Field Experiments

Studies were undertaken to improve the biological efficacy of the granulovirus (CpGV) of the codling moth, Cydia pomonella , by evaluating the performance of some formulation additives that might improve virus persistence and/or virus uptake by first instar larvae. Laboratory studies, using a leaf disc bioassay, demonstrated that 15% cane molasses incorporated within a formulation of purified CpGV dramatically reduced the median lethal exposure time (LET 50 ) to CpGV for neonate larvae at a CpGV dosage rate of 10 7 occlusion bodies (OBs) ml -1 . Screening of a range of other compounds showed that sucrose, fructose and sorbitol (at 10% concentrations) and extracts of apple flesh and skin also gave significant reductions in the LET 50 of CpGV formulations containing these ingredients. Pectin, malic acid and &#102 -farnesene did not significantly reduce the LET 50 . In a field trial, molasses included at 15% (v/v) in a CpGV formulation, containing a dosage rate of 10 12 OBs ha -1 , gave as good control of codling moth damage as virus formulations containing the 'sticker' 0.2% skimmed milk at higher dosage rates of 10 13 and 10 14 OBs ha -1 . Studies of CpGV persistence on foliage revealed no significant improvement of virus persistence on apple foliage using 10% or 15% molasses formulations. A second field trial demonstrated that 10% molasses, 10% sorbitol or 0.08% &#102 -farnesene significantly reduced codling moth deep damage to fruit when these ingredients were added to formulations of pure CpGV. Substantial sooty-mould growth ( Cladosporium spp.) was observed on apple foliage treated with formulations containing molasses, indicating that this formulation additive has secondary consequences that would need to be taken into account if molasses was to be used in commercial CpGV formulations. Nonetheless, these studies clearly demonstrate that major biological improvements in CpGV performance can be achieved by the incorporation of formulation additives, including molasses and several other compounds, that probably function as attractants and/or feeding stimulants for codling moth larvae.     

Evaluation of spray-dried lignin-based formulations and adjuvants as solar protectants for the granulovirus of the codling moth, Cydia pomonella (L)

Commercial formulations of the codling moth, Cydia pomonella L., granulovirus (CpGV) are limited by their short residual activity under orchard conditions in the Pacific Northwest. We evaluated spray-dried lignin-encapsulated formulations of CpGV for improved solar stability based on laboratory bioassays with a solar simulator and in field tests in an infested apple orchard. In laboratory tests, aqueous lignin formulations containing a high dosage of 3 x 10(10) occlusion bodies (OB)/L, with and without the additives titanium dioxide (TiO(2)) and sugar, provided significant solar protection of virus, i.e., mortality of codling moth exposed to lignin formulations that had been irradiated with 9.36 x 10(6) joules/m(2) was 92-94%, compared with 66-67% from a glycerin-stabilized product (Cyd-X) or suspension of pure unformulated virus at the same rates. By comparison, a lower dosage of the lignin formulation (3 x 10(8)OB/L) did not provide significant solar protection. Equivalent dosage-dependent patterns in solar protection were observed in further tests with the lignin formulation, when an intermediate (3 x 10(9)OB/L) as well as the low dosage provided no solar protection. Equivalent rates of a blank lignin formulation (containing no virus) did not affect larval mortality, suggesting a protective effect of the lignin on the virus at the high rate. The use of several spray adjuvants, 'NuFilm-17' and 'Organic Biolink' (sticker-spreaders at 0.06% v/v), 'Raynox' (sunburn protectant at 5% v/v), and 'Trilogy'(neem oil at 1% v/v) did not provide solar protection of a commercial CpGV preparation in laboratory tests. In season long orchard tests (Golden Delicious), the lignin formulation of CpGV applied at 6.57 x 10(12)OB/ha did not significantly improve control of codling moth or protection of fruit compared with Cyd-X at equivalent rates. Our studies show that lignin-based CpGV formulations provided solar protection at relatively high virus dosages. The testing of lignin formulations containing reduced virus concentrations may allow virus solar protection to be achieved at more economical rates.     

Field evaluations of concentrated spray applications of microencapsulated sex pheromone for codling moth (Lepidoptera: Tortricidae)

The application of a microencapsulated (MEC) sex pheromone formulation (Checkmate CM-F) for codling moth, Cydia pomonella (L.), in low volume, concentrated sprays was evaluated in a series of small plot and grower trials in apple, Malus domestica Borkhausen, and pear, Pyrus communis L. Preliminary tests found that MEC sprays applied at 172-207 kilopascals in 12-23 liters/ha deposited the highest density of microcapsules per leaf. The addition of a latex sicker did not increase the deposition of microcapsules. Small plot tests in 2004 compared the effectiveness of two low-volume sprayers against a standard high-volume spray (926 liters/ha) applied at 1,379 kilopascals. Moth catches and fruit injury were significantly lower in plots treated with the low-volume sprays compared with plots treated with the standard sprayer. These results suggest that concentrating the MEC formulation increases the deposition of microcapsules and improves its effectiveness. Larger trials were conducted with a low-volume sprayer in 4-ha plots within commercial apple (2005-2006) and pear orchards (2005) paired with similar plots treated with hand-applied pheromone dispensers. Levels of fruit injury were not significantly different between pheromone treatments in any of the three tests. Moth catches, however, were significantly higher in the MEC- versus the dispenser-treated apple plots in 2005. No difference was found in the fruit injury levels in MEC-treated apple orchards in 2005 caused by irrigation method, but moth catches were significantly higher in overhead versus undertree orchards. The advantages and current limitations of using MEC sex pheromone sprays to supplement current grower's management strategies for codling moth is discussed.     

Evaluation of lignins and particle films as solar protectants for the granulovirus of the codling moth,Cydia pomonella

The identification of effective solar protectants for field application of the codling moth, Cydia pomonella (L.), granulovirus (CpGV) is of interest to improve its efficacy and commercial viability as a biological pesticide. We evaluated several materials as potential adjuvants to protect CpGV from ultraviolet degradation. In laboratory tests with a solar simulator (9.36×10⁶ J/m²), the addition of kaolin clay (Surround® WP at 3 and 6%, w/v), a paraffin wax-based emulsion (SPLAT? at 5%, v/v), and a bark extract trans-cinnamaldehyde combined with a film agent (both at 1%, v/v) did not significantly reduce larval entries or increase larval mortality in irradiated apples that were treated with a commercial CpGV product (Cyd-X). In semi-field tests in an apple orchard, a spray-dried lignin formulation containing CpGV (6.57×10¹² OBs/ha) and a lignin-based adjuvant used with Cyd-X (both applied at 4.7–5.6 kg lignin/ha) significantly improved residual activity of CpGV compared with Cyd-X alone applied at the same rate. However, the benefits were short lived and could not be detected after 7 days. In orchard tests, we evaluated two additional refined lignin-products (Lignosulfonate and Vanisperse? CB at 5.61 kg/ha) and two particle film materials (kaolin clay, ‘Cocoon?’, and calcium with boron ‘Eclipse?’) as adjuvants for UV protection of Cyd-X (6.57×10¹² OBs/ha) in tests against a dense codling moth infestation. Although all virus treatments were highly effective (causing ≥90% larval mortality), no significant effects of the adjuvant treatments could be detected. In these latter tests, the use of a silicone based wetting agent at 0.025% (v/v) may have been beneficial at increasing mortality among older larvae inside the fruit.     

Overwintering of codling moth (Lepidoptera: Tortricidae) larvae in apple harvest bins and subsequent moth emergence.

Codling moths, Cydia pomonella (L.), have long been suspected of emerging from stacks of harvest bins in the spring and causing damage to nearby apple and pear orchards. With increased use of mating disruption for codling moth control, outside sources of infestation have become more of a concern for growers using pheromone based mating disruption systems. Studies were designed to provide information on bins as a source of codling moth and the pattern of codling moth emergence from stacks of bins. In these studies, codling moth larvae colonized wood harvest bins at a much higher frequency than harvest bins made of injection molded plastic (189 moths emerged from wood compared with five from plastic). There was no statistical difference in the number of moths infesting bins that had been filled with infested fruit compared with bins left empty at harvest. This suggests that codling moth enter the bins during the time that the bins are in the orchard before harvest. Emergence of laboratory reared adult codling moth from wood bins placed in stacks was found to be prolonged compared with field populations. Temperature differences within the bin stacks accounted for this attenuated emergence pattern. Covering bin stacks with clear plastic accelerated codling moth development in the upper levels of the stack. Codling moth emergence patterns from plastic-covered stacks more closely coincided with male flight in field populations. This information could be important in developing a technique for neutralizing codling moth-infested bins, and in understanding how infested bins may influence pest management in fruit orchards that are located near bin piles. Implications for control of codling moth in conventional orchards and in those using mating disruption as the principal component of an integrated pest management system include increased numbers of treatments directed at areas affected by infested bins.     

New method for testing solar sensitivity of commercial formulations of the granulovirus of codling moth (Cydia pomonella, Tortricidae: Lepidoptera)

A method for screening codling moth granulovirus (CpGV) formulation sensitivity to sunlight using specially prepared half apples and a solar simulator is described. The half apple preparation allows an even coverage of virus over the surface of the fruit that would not be possible using whole apples. Leaves and artificial medium were not usable for extended periods of exposure in the solar simulator due to excess drying. Fruit was sprayed with 10⁻³ and 10⁻⁵ dilutions of three commercial formulations of CpGV (Carpovirusine, Cyd-X, and Virosoft) and infested with codling moth neonates. Half of the sprayed fruit was exposed to 650 W/m² for 4 h in an Atlas Suntest CPS solar simulator resulting in an accumulated radiant energy of 9.36 × 10⁶ J/m² before they were infested with neonate codling moth larvae. Spraying non-irradiated fruit with the 10⁻³ dilution of Cyd-X and Virosoft resulted in nearly 100% mortality of neonate larvae. Irradiation reduced viral activity by 71-98% at the 10⁻³ dilution and by up to 32% at the 10⁻⁵ dilution relative to non-irradiated fruit. The procedures utilized enabled good preservation of the fruit throughout the incubation period and minimized invasion of the fruit by plant pathogens and saprophytic organisms. This laboratory method for screening candidate formulations and potential UV protectants could conserve time and resources by eliminating adjuvants with less potential in laboratory tests and field testing only the most promising candidates. It also enables year-round testing.     

Comparative activity of baculoviruses against the codling moth Cydia pomonella and three other tortricid pests of tree fruit

The granulovirus of Cydia pomonella (L.) (CpGV) offers potential for selective control of codling moth. Two major limitations of CpGV are its narrow host range and lack of persistence in the orchard agroecosystem. The nucleopolyhedroviruses of the alfalfa looper Autographa californica (Speyer) (AcMNPV) and those of the celery looper Anagrapha falcifera (Kirby) (AfMNPV) have broad host ranges. Comparative assays of CpGV, AcMNPV, and AfMNPV against codling moth neonate larvae revealed a 54-93-fold greater susceptibility of codling moth to the granulovirus than to the two nucleopolyhedroviruses based on the LC(50) values for each virus. The LC(50)s for CpGV, AfMNPV, and AcMNPV were 32.7 capsules/mm(2), 1.77 x 10(3) occlusion bodies (OBs)/mm(2), and 3.05 x 10(3)OBs/mm(2), respectively. The LT(50) determined for AfMNPV using an approximate LC(95) of the virus against neonate larvae was 3.6 days. Histological examination of tissues in moribund codling moth larvae that had been treated with AfMNPV revealed the presence of nonoccluded and unenveloped virus rods in midgut tissue. Neither OBs nor signs of infection were detected in other tissues. The activity of AfMNPV was also evaluated in three other tortricid apple pests (obliquebanded leafroller, Choristoneura rosaceana (Harris); Pandemis leafroller, Pandemis pyrusana Kearfott; and the oriental fruit moth, Grapholitha molesta (Busck)). Codling and Oriental fruit moths were significantly more susceptible to AfMNPV than were the two leafroller species.     

Combined approaches using sex pheromone and pear ester for behavioural disruption of codling moth (Lepidoptera: Tortricidae)

Attractive properties of pear ester, ethyl (E,Z)‐2,4‐decadienoate, and codlemone, (E,E)‐8,10‐dodecadien‐1‐ol, the sex pheromone of codling moth, Cydia pomonella (L.), were utilized in experiments on behavioural disruption of mating. Standard dispensers loaded with codlemone alone or in combination with pear ester (combo) were applied at 500–1000/ha. Larger (10‐fold) combo dispensers (Meso) were evaluated at a rate of 80/ha. The addition of microencapsulated pear ester, PE‐MEC, sprayed with insecticides at 30 ml/ha was also evaluated. Male moth catches in unmated female‐baited traps were lower in standard combo dispenser than in codlemone dispenser–treated plots. Female moth catch in traps baited with the combination of pear ester, codlemone and acetic acid was lower in standard combo dispenser than in codlemone dispenser–treated plots. In 12 comparative experiments spanning from 2006 to 2012, male moth catch in unmated female‐baited traps was consistently and significantly lower in combo than in codlemone dispenser–treated plots. Male catch in codlemone‐baited traps did not differ between dispenser treatments in eight studies from 2006 to 2009. These results emphasize the benefit of alternatively using traps baited with unmated females over codlemone lures for the analysis of dispenser activity. Fruit injury was significantly reduced with the addition of PE‐MEC to insecticide applications across untreated and dispenser treatments. Proportion of unmated females trapped was higher in standard combo dispenser than in codlemone dispenser–treated and untreated plots. Similarly, the proportion of unmated females caught was higher in the Meso combo dispenser than in nearby or distant codlemone dispenser–treated plots. These field studies conducted in apple over 3 years demonstrate that adding pear ester both to pheromone dispensers, either standard or Meso, and to supplementary insecticide sprays can provide a significant increase in the disruption of sexual communication, reductions in female mating and reductions in fruit injury.     

Field evaluation of commercial formulations of the codling moth granulovirus: persistence of activity and success of seasonal applications against natural infestations of codling moth in Pacific Northwest apple orchards

Inundative applications of the codling moth (CM), Cydia pomonella L., granulovirus (CpGV), which target neonate larvae before or during initial entry into fruit, offer potential for selective control of this key pest. In field tests on apple we compared the persistence and efficacy of single applications of three CpGV products approved for organic orchards in North America. In addition, the success of repeated (2–14) applications of one product (Cyd-X) as a principal control measure for CM in apple orchards was monitored following operational use by cooperating growers at four separate locations. In the first study, an early season application of all products at label rates remained highly effective for the first 24 h (averaging 94% larval mortality relative to controls) and moderately effective after 72 h (averaging 71% mortality) during dry sunny conditions. Significant activity remained up to 14 days, suggesting prolonged survival of the virus in UV-protected locations, such as the calyx of fruit. A second application later in the season was slightly less effective. Data obtained from commercial sites provide circumstantial evidence for the effectiveness of well-timed CpGV applications against CM outbreaks. In all cases where first generation larvae were targeted beginning at egg hatch (≈250 degree days) and treated areas monitored (0.3–1.6 ha plots), fruit damage during the second larval generation was reduced or eliminated. Based on the number of live larvae recovered throughout the season, mortality rates remained high (80.3–100% across sites). The cumulative number of moths caught in pheromone-baited traps was reduced (66–94%) in the second flight. Data from tree bands placed to catch diapause-destined larvae indicated overwintering generations remained low in treated sites (0.18 larvae/band).     

Suppression of leopard moth (Lepidoptera: Cossidae) populations in olive trees in Egypt through mating disruption

The leopard moth, Zeuzera pyrina (L.) (Lepidoptera: Cossidae), is a damaging pest for many fruit trees (e.g., apple [Malus spp.], pear [Pyrus spp.] peach [Prunus spp.], and olive [Olea]). Recently, it caused serious yield losses in newly established olive orchards in Egypt, including the death of young trees. Chemical and biological control have shown limited efficiency against this pest. Field tests were conducted in 2005 and 2006 to evaluate mating disruption (MD) for the control of the leopard moth, on heavily infested, densely planted olive plots (336 trees per ha). The binary blend of the pheromone components (E,Z)-2,13-octadecenyl acetate and (E,Z)-3,13-octadecenyl acetate (95:5) was dispensed from polyethylene vials. Efficacy was measured considering reduction of catches in pheromone traps, reduction of active galleries of leopard moth per tree and fruit yield in the pheromone-treated plots (MD) compared with control plots (CO). Male captures in MD plots were reduced by 89.3% in 2005 and 82.9% in 2006, during a trapping period of 14 and 13 wk, respectively. Application of MD over two consecutive years progressively reduced the number of active galleries per tree in the third year where no sex pheromone was applied. In all years, larval galleries outnumbered moth captures. Fruit yield from trees where sex pheromone had been applied in 2005 and 2006 increased significantly in 2006 (98.8 +/- 2.9 kg per tree) and 2007 (23 +/- 1.3 kg per tree) compared with control ones (61.0 +/- 3.9 and 10.0 +/- 0.6 kg per tree, respectively). Mating disruption shows promising for suppressing leopard moth infestation in olives.     

Particle films for suppression of the codling moth (Lepidoptera: Tortricidae) in apple and pear orchards

Studies were conducted in 1997 and 1998 to evaluate the effects of three particle film formulations consisting of kaolin and adjuvants on neonate larvae, ovipositing adult females, and eggs of the codling moth, Cydia pomonella (L.). Neonate larval walking speed, fruit discovery rate, and fruit penetration rate on apple host plants coated with particle films were significantly lower than on host plants without particle films in laboratory assays. Females oviposited less on host plants covered with a particle film residue than on untreated plants in laboratory choice and no-choice tests. Hatch rate of codling moth neonate larvae was unaffected by particle films sprayed on host plants either before or after oviposition. Fruit infestation rates were significantly reduced on particle film-treated trees compared with untreated trees for both first- and second-generation codling moth in field trials in both apple and pear orchards. Particle films appear to be a promising supplemental control approach for codling moth in orchards where moth density is high, and may represent a stand-alone method where moth densities are lower.     

Potential for outbreaks of leafrollers (Lepidoptera: Tortricidae) in California apple orchards using mating disruption for codling moth suppression

Two species of leafrollers, Argyrotaenia citrana (Fernald) and Pandemis pyrusana Kearfott, represent serious obstacles to the implementation of mating disruption for control of codling moth in coastal California apple orchards. Larval and adult densities of A. citrana and P. pyrusana and subsequent fruit damage were compared under different codling moth control treatments. Leafroller larval counts and levels of fruit damage were significantly higher in most plots that were untreated or treated only with codling moth pheromone. Leafroller fruit damage levels in these plots were commonly between 10 and 15% at harvest. As summer larval counts were good predictors of fruit damage levels, larval sampling could be a useful tool for predicting leafroller outbreaks. Use of pheromone trapping for A. citrana to detect localized outbreaks within an orchard was not useful and failed to correlate with larval numbers, whereas adult monitoring for P. pyrusana appears more promising. Efforts to implement a codling moth mating-disruption program in California must include changes in strategies for monitoring and controlling leafroller species.     

Biocontrol of Pests of Apples and Pears in Northern and Central Europe: 1. Microbial Agents and Nematodes

The viral, bacterial, fungal and nematode pathogens of arthropod pests of apple and pear in northern and central Europe and their use as biocontrol agents are reviewed. Baculoviruses are important viral pathogens of several lepidopterous pests of apple and pear but other viral pathogens have not been investigated in depth and are little known. The granuloviruses of codling moth, Cydia pomonella (CpGV), and to a lesser extent, of the summer fruit tortrix moth, Adoxophyes orana (AoGV), have been researched extensively and are exploited as biological control agents. Commercial development and use has been limited because of their high costs, slow action, short persistence and specificity relative to broad-spectrum pesticides. The widespread development of strains of codling moth multi-resistant to insecticides and the desire to reduce dependence on pesticides have improved the commercial prospects of CpGV and use is likely to increase. The development of a genetically improved egt-strain of CpGV (lacking the ecdysteroid-UDP glucosyl transferase gene) in the UK is a significant breakthrough, though commercialization in the UK may be difficult due to adverse public attitudes to the release of genetically-modified microorganisms. Future research and development approaches include further genetic manipulation of CpGV and AoGV to improve potency, speed of kill and/or persistence, improvement of formulation (to reduce UV light sensitivity) and development of cheaper mass production techniques and possibly in vitro production. A systematic search for baculoviruses and other viruses of apple and pear pests is likely to reveal important new opportunities. The most important bacterial pathogen used as a biological control agent is Bacillus thuringiensis (Bt). However, Bt products currently available have limited effectiveness against many orchard pests due to the pests' cryptic life habits. The HD-1 Bt strain has been investigated and used extensively for control of leaf-rolling tortricid larvae and is widely used, but efficacy is moderate. Advances in biotechnology and genetic engineering provide opportunity for development of Bt strains designed specifically to control orchard pests, but this has not yet been done for commercial reasons. Other research approaches include the evaluation of new Bt products developed for other markets worldwide and the bioassay of strains from Bt collections against specific apple or pear pests. Entomopathogenic fungi provide good opportunity for development as biological control agents of apple and pear pests. The main factor limiting their effectiveness is the requirement for high humidities and moderate temperatures for spore germination and development. For foliar pests, a useful starting point for research might be the control of sucking pests which excrete honeydew (e.g. Cacopsylla sp. or aphids) or those that inhabit protected microenvironments (e.g. Dasineura sp.). Key areas for research are improved formulation, the selection of low temperature-active strains, field evaluation and avoiding possible adverse effects of fungicides. An alternative approach is to examine the exploitation of entomopathogenic fungi in soil, to which many species of entomopathogenic fungi are adapted ecologically. Apple and pear orchards provide long-term stable habitats where populations of entomopathogenic fungi in soil are likely to be large. There are few important soil pests of apple or pear. However, many species spend part of their life in soil, mainly to pupate or overwinter, where they may be targeted by fungal entomopathogenic biocontrol agents. Entomopathogenic nematodes have many attributes which favour them as biological control agents. However, their requirement for surface moisture for survival and movement means there are only limited prospects for using them as biological control agents for foliar pests. As with entomopathogenic fungi, there are better prospects for control of pests that occur in soil. Microbial pathogens and entomopathogenic nematodes are important components of the natural enemy complex of apple and pear orchards and more effort needs to be devoted to fostering them and exploiting them as biocontrol agents in sustainable, biologically-based Integrated Pest Management programmes. They can in many cases be mass produced at low cost by bulk fermentation processes and applied as sprays (as 'biopesticides') and are, at least potentially, ideal biological control agents for many apple or pear pests. Important general characteristics are their comparative environmental and human safety, compatibility with other control strategies in Integrated Pest Management programmes and reproductive capacity. They tend to be effective in a narrower range of environmental conditions than pesticides, but there is considerable potential to improve their effectiveness by improved formulation, strain selection and genetic manipulation. They are often host-specific and thus, offer restricted marketing opportunities, which is a significant barrier to development and commercialisation. Registration procedures and associated fees for microbial agents are a further significant barrier. Such requirements do not apply currently to nematodes.     

A test of fruit varieties on entry rate and development by neonate larvae of the codling moth,Cydia pomonella

The rate of entry by neonate larvae of the frugivorous codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), into fruit material was investigated. We used no‐choice bioassays in climate‐controlled rooms to assay larval entry across four host plant species (apple, pear, quince, walnut) and three varieties within a single fruit species (apple). Larvae successfully entering apples were reared to adulthood, and we collected tissue samples from apples which were successfully colonized in order to determine sucrose concentrations. This information was used to evaluate differences in adult moth size, development time, and pulp sucrose concentration due to apple variety. Four important findings emerged: (1) neonate larvae had the highest frequency of entry (86% of larvae) into apple fruits, compared with pear (78%), quince (56%), and walnut (32%); (2) the frequency of larval entry into immature apples differed across apple varieties, and larval entry rate was highest in variety Golden Delicious (72%), compared with Granny Smith (46%) and Red Delicious (64%); (3) on average, adult moths were larger and development times were shorter on the variety with the highest entry frequency (Golden Delicious); and (4) apple pulp sucrose concentrations were higher for Golden Delicious (17.5 μg mg^?1) than for either Granny Smith (15.9 μg mg^?1) or Red Delicious (15.1 μg mg^?1) varieties, which correlates positively with entry and development data. We conclude that host fruit species and varietals within a species affect the entry rate of neonate codling moth larvae in no‐choice assays. We hypothesize that larval development is influenced by mean sucrose concentrations or other phytochemical differences associated with host fruit varieties.     

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

Sequence 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.     

Optimizing use of codling moth granulovirus: effects of application rate and spraying frequency on control of codling moth larvae in Pacific Northwest apple orchards

New formulations of the codling moth, Cydia pomonella (L.), granulovirus (CpGV) [family Baculoviridae, genus Granulovirus] are commercially available in North America. In field tests on apple (Malus sp. 'Delicious'), we compared different application strategies for CpGV (Cyd-X, Certis USA, Clovis, CA) used in full-season programs against high pest populations. In replicated single tree plots, three rates (0.073, 0.219, and 0.438 liter ha(-1)) and application intervals (7, 10, and 14 d) killed 81-99% of larvae in fruit and reduced the number of mature larvae recovered in tree bands by 54-98%. Although the proportion of deep entries declined by 77-98%, the amount of fruit injury was not reduced compared with controls. There was a statistical trend between increasing dosage and spray frequency intervals and virus effectiveness, but no interaction between these factors. In a commercial orchard, we assessed a standard (0.219 liter ha(-1)) and two reduced rates of the virus (0.146 and 0.073 liter ha(-1)) applied in a weekly spray program in replicated 0.2-ha blocks. In the first generation, fruit injury was reduced in virus-treated compared with three untreated blocks although the decrease was only significant at the standard rate. Mortality rates of larvae (in fruit) were > or =90%, dose dependent, and comparable with rates observed from individual trees sprayed with equivalent treatments in the previous study. Rates of larval mortality declined at all dosages (81-85%) in the first part of the second generation. Most damage and proportionally less mortality occurred in the upper canopy. High pest pressures and untreated blocks contributed to significant damage and the study was terminated early. These data suggest virus programs can be tailored according to the localized pest pressure, but it may not prevent economic damage in high-pressure situations.     

Toxicity and residual activity of methoxyfenozide and tebufenozide to codling moth (Lepidoptera: Tortricidae) and oriental fruit moth (Lepidoptera: Tortricidae)

A series of studies were conducted to examine the residual activity and toxicity of the ecdysone agonists tebufenozide and methoxyfenozide to codling moth, Cydia pomonella (L.), and oriental fruit moth, Grapholita molesta (Busck), in North Carolina apple systems. Methoxyfenozide exhibited greater activity than tebufenozide against codling moth eggs in dose-response bioassays, with a 4.5- and 5.3-fold lower LC50 value to eggs laid on fruit treated before or after oviposition, respectively. Oriental fruit moth eggs were 57- and 12-fold less sensitive to methoxyfenozide than were codling moth eggs on fruit treated before and after oviposition, respectively. Methoxyfenozide was effective in reducing larval entries of both codling moth and oriental fruit moth in field residual activity bioassays, exhibiting activity for at least 28 d after application. Residue breakdown on fruit was approximately 80% at 28 d after treatment for both methoxyfenozide and tebufenozide, with the most rapid residue decline (60%) occurring during the first 14 d after application. Two applications of methoxyfenozide applied at 14-d intervals provided better canopy coverage and higher residue levels than one application. Spray volume (683 versus 2,057 liters/ha) did not affect the efficacy of methoxyfenozide. Leaf and fruit expansion during the season was measured to determine potential plant-growth dilution effects on residual activity. There was very little increase in leaf area after mid May, but increase in fruit surface area over the season was described by a second order polynomial regression. Implications for codling moth and oriental fruit moth management programs are discussed.     

Parasitoid exploitation of the seasonal variation in host plant volatile emission for herbivore location

Volatile compounds from the apple, Malus domestica Borkh. (Rosaceae), change considerably as the season progresses, and this is successfully exploited by the female codling moth Cydia pomonella L. (Lepidoptera, Tortricidae), as it searches for oviposition sites. In this study, we investigated the effect of seasonal emissions of apple fruit volatiles on the host location behaviour of a parasitoid of the codling moth larvae, Hyssopus pallidus (Askew) (Hymenoptera: Eulophidae). In dual choice olfactory bioassays, the behaviour of the parasitoid in response to apple cues was observed over the complete 2003 growing season. Our results show that codling moth infested apples evoked a strong response from the parasitoid at the beginning of the season, until July. Then, attraction dropped drastically, increasing again at the beginning of August. At the end of the growing season, just prior to harvest, infested apples hardly evoked any behavioural response. Interestingly enough, mid‐season emissions of healthy apples were per se attractive to the parasitoid, and even preferred over volatiles from infested apples. Simultaneous volatile collections from healthy apples on twigs in the field were analysed throughout the season, showing that the overall quantity of headspace volatiles peaks at the beginning of June and mid‐August. The seasonal volatile emission is correlated with the behaviour of the parasitoid during the fruit ripening stage. The results are discussed in relation to the use of H. pallidus as a potential biocontrol agent, in order to enhance current integrated pest management (IPM) programs.     

Host status of fresh prunes by potential quarantine pests in laboratory tests and evaluation of packinghouse culls.

The status of fresh prunes, Prunus domestica L., as a host for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae); peach twig borer, Anarsia lineatella Zeller (Lepidoptera: Gelechiidae); omnivorous leafroller, Platynota stultana Walshingham (Lepidoptera: Tortricidae); oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae); navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae); and walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae), was investigated in laboratory tests and by examination of packinghouse culls. In laboratory no-choice tests, the mean number of adults reared per fruit was 0.01 for codling moth, 0.08 for omnivorous leafroller, 0 for oriental fruit moth, and 1.6 for navel orangeworm. In choice tests the mean number of adults reared per apple or fresh prune was for codling moth, 0.78 and 0.02 (significantly different); for omnivorous leafroller, 0.05 and 0.02; and for oriental fruit moth, 2.07 and 0 (significantly different), respectively. Walnut husk fly oviposited in fresh prunes in no-choice tests but pupae did not develop from the fruit. In choice tests, walnut husk fly did not oviposit in fresh prunes when caged with its normal host, green walnuts, in which large numbers of pupae developed. Inspection of packinghouse culls for immature insects showed that fresh prunes with possible larval feeding sites in the form of frass or fruit gum extrusions were lighter in weight, significantly less firm, similar in color, and had significantly higher soluble solids than noninfested fruit. Based on packinghouse cull samples, 1 fresh prune per 133 harvested fruit would be expected to show possible insect damage. Eleven peach twig borer larvae were found in fresh prune cull samples (213.9 kg) removed from a 16,744.5-kg harvest. The calculated level of infestation was 1 infested fruit per 8,501.8 fruit harvested or per 21.7 cartons of medium-sized packed fruit. Based on our results, the risk of infestation of fresh prunes by the insects in this study would be minimal in fruit exported from the San Joaquin Valley of California.