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.     

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.     

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.     

Incidence and transmission of a granulovirus in a large codling moth [Cydia pomonella L. (Lepidoptera: Tortricidae)] rearing facility

Incidences of potential per os Cydia pomonella granulovirus (CpGV) transmission within a large codling moth colony were identified. CpGV was detected in the water which is used to wash egg sheets. When pre-neonates were extracted from eggs prior to emergence and tested for the presence of CpGV, 40% were found to carry amounts of CpGV detectable by a polymerase chain reaction (PCR) assay, suggesting possible transovarial transmission of the virus. Although symptoms typical of virus infection and larval death were found infrequently within communal rearing trays, the frequency with which CpGV DNA was detected by PCR assays increased from a mean of 31% of 10-day-old larvae to 94% of 25-day-old larvae. CpGV in codling moth cadavers remained virulent after being held at 60 degrees C for 3 days under conditions similar to the treatment of spent diet at the rearing facility before its disposal. PCR tests of surface samples taken from air filters and rearing rooms of the rearing facility were found to contain CpGV. Bioassays of surface samples from the diet trash bin and a filter through which outside air is passed before entering the rearing chambers resulted in significant codling moth neonate mortality. The virulence of CpGV in dust from the spent diet and the original inadvertent positioning of the diet trash bin directly below one of the air intake ducts are suggested as a possible additional source of CpGV contamination within the facility.     

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.     

Uptake of Granulovirus from the Surface of Apples and Leaves by First Instar Larvae of the Codling Moth Cydia pomonella L. (Lepidoptera: Olethreutidae)

Cydia pomonella granulovirus (CpGV) has received considerable attention as a potential microbial insecticide for the control of the codling moth (Cydia pomonella L.) , a worldwide pest of apples. Laboratory experiments were established to investigate virus uptake by first instar larvae, using a novel leaf disc bioassay technique. Virus uptake was found to be independent of active feeding and larvae became infected simply by walking or browsing on sprayed leaf disc surfaces in as little time as 3.5 min. Infection increased as a function of time spent on the leaf disc surface and a linear log time/probit mortality relationship could be fitted. The bioassay technique used has potential for the realistic laboratory testing of virus spray formulations. A field experiment showed that virus infection could be contracted by newly hatched codling moth larvae both from the surface of sprayed leaves and sprayed fruit. The potential for exploiting this knowledge for improving spray formulations 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.     

Field activity and storage stability of Anagrapha falcifera nucleopolyhedrovirus (AfMNPV) in spray-dried lignin-based formulations

A multiple-embedded nucleopolyhedrovirus isolated from Anagrapha falcifera (Kirby) (AfMNPV) has potential to be developed into a microbial bioinsecticide because the host range includes several economic pests. We tested spray-dried AfMNPV formulations after storage for insecticidal activity based on bioassays with neonate Trichoplusia ni (Hübner). Eight experimental lignin-based spray-dried formulations, a glycerin-based formulation, and an unformulated sample were made with virus stock from three commercial production lots. Samples of these formulations were stored at 30 degrees C in individually sealed sample containers for destructive sampling after 1, 3, and 6 mo whereas the remaining product was stored in glass jars under refrigeration for up to 30 mo. Spray drying did not significantly reduce the initial LC50s of AfMNPV in experimental formulations compared with unformulated virus that was not spray dried. Refrigerated storage for 6 mo did not significantly lower virus activity of formulated samples compared with the unformulated AfMNPV stored frozen, while samples stored for 30 mo had higher LC50 values determined by both droplet and leaf feeding assays. When stored at 30 degrees C, most formulations (22 of 24) maintained insecticidal activity for 3 mo, but most (21 of 24) lost significant activity after 6 mo of storage. The glycerin-based formulation also lost activity within 6 mo of storage at 30 degrees C when compared with frozen unformulated virus, but did not lose activity when stored refrigerated for up to 30 mo. These formulations were evaluated after 7 mo at 4 degrees C for residual insecticidal activity when applied to field grown cabbage. Insecticidal activity was determined against T. ni neonates for treated leaf samples collected at 3, 7, 27, and 51 h after application of 2.5 x 10(12) obs/ha. Field tests showed no differences in activity among samples of stored formulations and one freshly made formulation. Spray-dried formulations had significantly higher insecticidal activity (67.5% mortality) compared with the unformulated treatment (30% mortality) sampled 3 h after application. At 3, 7, and 27 h after application, the spray-dried formulations had higher residual activity (67%, 59%, and 42% mortality, respectively), compared with the commercial glycerin-based formulation (61%, 38%, and 23% mortality, respectively). These experiments demonstrated that AfMNPV in lignin-based spray-dried formulations had a shelf-life of up to 3 mo at 30 degrees C and up to 30 mo at 4 degrees C, and with longer residual insecticidal activity in the field compared with unformulated or a glycerin formulation.     

Storage stability of Anagrapha falcifera nucleopolyhedrovirus in spray-dried formulations

A multiply embedded nucleopolyhedrovirus isolated from Anagrapha falcifera (Kirby) (AfMNPV) can lose insecticidal activity during months of dry storage in ambient room conditions. We tested the spray-dried AfMNPV formulations after storage for up to 1 year at room temperatures for insecticidal activity against neonate Trichoplusia ni (Hübner). Experimental formulations were made using combinations of corn flours, lignin, and sucrose, and were selected based on previous work which demonstrated that these formulations resisted solar degradation in field experiments. Twelve experimental formulations (organized in three groups of four formulations) compared the effect of (1) the ratio of formulation ingredients (lignin and corn flour) to virus concentration, (2) different sources of lignin, or (3) different corn flours and sugar. Based on a single-dose plant assay with these 12 formulations, none of the formulations lost significant activity due to the drying process, when compared with the unformulated wet AfMNPV. Samples of the 12 dried formulations were stored at room (22+/-3 degrees C) and refrigerated (4 degrees C) temperatures. Insecticidal activity (LC(50)) was determined with a dosage-response assay for neonates fed on treated cotton-leaf disks. After 6 (or 9) and 12 months storage, refrigerated samples maintained insecticidal activity better than corresponding samples stored at room temperatures with LC(50)s that averaged 2.0 x 10(6) polyhedral inclusion bodies per milliliter (pibs/ml) for refrigerated samples and 5.4 x 10(6) pibs/ml for samples stored at room temperatures. Compared with unformulated stock virus stored frozen, six formulations stored at room temperature and 10 formulations stored in the refrigerator did not lose significant insecticidal activity after 1 year based on overlapping 90% confidence intervals. Changing the ratio of virus to formulation ingredients did not provide a clear trend over the range of concentrations tested, and may be less important for shelf-life of virus activity compared with formulations made with different ingredients. Two of the four formulations made with different lignins were about 15 times less active after 1 year at room temperature compared with refrigerated samples, indicating that specific formulation ingredients can affect storage stability. Formulations that contained sugar generally maintained activity during storage better than formulations without sugar. Unformulated virus stock maintained insecticidal activity (ranged from 0.20 to 2.5 x 10(6) pibs/ml) better during storage than dried formulations with LC(50)s that ranged from 0.39 to 27 x 10(6) pibs/ml. Unformulated virus stock, which is essentially a suspension of virus occlusion bodies in homogenized insect cadavers, did not lose activity when stored at refrigerated or room temperature. We believe that stability of AfMNPV insecticidal activity during storage as dry formulations is related to the general composition of the formulation and that sugar may play a critical role in maintaining insecticidal activity.     

苹果蠹蛾抗药性研究进展

苹果蠹蛾是世界各国高度关注的严重危害苹果生产的外来有害生物。该虫于20世纪50年代在我国首次报道,目前是我国一类进境检疫性有害生物,正严重威胁我国苹果主产区的水果生产安全。苹果蠹蛾以幼虫钻蛀到果实内部为害,防治难度高,对其主要采用化学农药、交配干扰和苹果蠹蛾颗粒体病毒进行防治。由于农药的长期大量使用,苹果蠹蛾已对有机磷、氨基甲酸酯、拟除虫菊酯、昆虫生长调节剂、阿维菌素和苹果蠹蛾颗粒体病毒等不同类型的杀虫剂产生了抗药性。本文总结了国内外有关苹果蠹蛾抗药性现状和抗药性机理方面的研究,并分析了其对几种农药产生抗性的主要原因,同时结合国外苹果蠹蛾防治和抗药性相关研究,以及其在我国发生与防治的现状,提出该虫抗药性治理策略,即及时对我国疫区苹果蠹蛾的抗药性现状进行监测,在此基础上,注意科学地使用化学农药,并结合农业防治和生物防治等措施对该虫进行综合治理。     

Fate of codling moth (Lepidoptera: Tortricidae) in harvested apples held under short photoperiod

Codling moth, Cydia pomonella L., is a cosmopolitan pest of pome and stone fruits. It has been identified as a quarantine pest of concern in a number of countries where it is not known to occur, most of them tropical or subtropical countries. Although considerable work has been done on the basic biology and physiology of this temperate pest, little is known on its potential to develop and establish in tropical environments with short photoperiods and few to no days below 10 degrees C. Apples were harvested over three field seasons (2007-2009) from unmanaged orchards in central Washington State and subjected to simulated commercial cold storage at 1.1 +/- 2 degrees C for up to 119 d. After cold storage, infested fruits were held at 20 degrees C under a 12:12 L:D photoperiod for up to 6 mo. Over the entire experiment only 27% of the larvae collected exited the fruit and cocooned. Of those 27%, only 1.06% of larvae held under a 12:12 L:D photoperiod successfully emerged as moths. No moths emerged when host fruit would be available in a representative importing country in the tropics over the 3 yr of testing. These results indicate that codling moth in apples from the Pacific Northwest pose little threat of surviving and establishing in tropical regions where daylength is insufficient to break diapause and the chilling requirement is not met.     

Optimization of spray-drying conditions for the large-scale preparation of Bacillus thuringiensis var. israelensis after downstream processing

Reduction of water activity in the formulations of mosquito biocontrol agent, Bacillus thuringiensis var. israelensis is very important for long term and successful storage. A protocol for spray drying of B. thuringiensis var. israelensis was developed through optimizing parameters such as inlet temperature and atomization type. A indigenous isolate of B. thuringiensis var. israelensis (VCRC B-17) was dried by freeze and spray drying methods and the moisture content and mosquito larvicidal activity of materials produced by the two methods were compared. The larvicidal activity was checked against early fourth instars Aedes aegypti larvae. Results showed that the freeze-dried powders retained the larvicidal activity fairly well. The spray-dried powder moderately lost its larvicidal activity at different inlet temperatures. Between the two types of atomization, centrifugal atomization retained more activity than the nozzle type atomization. Optimum inlet temperature for both centrifugal and nozzle atomization was 160 degrees C. Keeping the outlet temperature constant at 70 degrees C the moisture contents for the spray-dried powders through centrifugal atomization and freeze-dried powders were 10.23% and 11.80%, respectively. The LC(50) values for the spray-dried and freeze-dried powders were 17.42 and 16.18 ng/mL, respectively. Spore count of materials before drying was 3 x 10(10) cfu/mL and after spray drying through nozzle and centrifugal atomization at inlet and outlet temperature of 160 degrees C/70 degrees C were 2.6 x 10(9) and 5.0 x 10(9) cfu/mL, respectively.     

Evaluation of a granulovirus (PoGV) and Bacillus thuringiensis subsp. kurstaki for control of the potato tuberworm (Lepidoptera: Gelechiidae) in stored tubers

Liquid suspensions and dry formulations of a granulovirus (family Baculoviridae, genus Granulovirus, PoGV) derived from infected larvae and the bacterium Bacillus thuringiensis subsp. kurstaki (Berliner) (Btk) were evaluated for control of the potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), in stored tubers. Laboratory bioassays at 25 degrees C showed that both PoGV and a wettable powder (WP) formulation of Btk incorporated with carriers (water, talc, sand, diatomaceous earth, and kaolin clay), were effective against neonate larvae. Depending on the technique, 100% larval mortality was achieved at concentrations as low as 0.025 larval equivalents (LE) PoGV per kg tuber and 150 mg Btk WP per kg tuber. However, 100% mortality was never achieved with tests on preinfested tubers, ostensibly due to the higher dosage required to kill older instars inside tubers. The most effective PoGV formulations were dipping (water) and talc, with dipping most effective for postinfestation treatments, causing up to 91.6% mortality at 0.4 LE per kg. There was no significant effect of formulation in the Btk treatments. The protective effects of residues were also evaluated under longer-term storage conditions. Batches of tubers treated with PoGV or Btk via dipping (up to 0.1 LE and 150 mg WP per kg tuber) were stored in cages containing an initial potato tuberworm infestation (10% of tubers). Although potato tuberworm populations were reduced by up to 98.4% after 2 mo at 25 degrees C, no treatments prevented the development and reproduction of the F1 generation. The sprouting of stored tubers seemed to be a limiting factor for sustained control. No significant treatment effects were detected in similar cages held at 12 degrees C for 4.5 mo. Improved strategies for the application of PoGV and Btk for long-term potato tuberworm control in tuber stores, including the use of chemical sprout suppressants, are discussed.     

The occurrence and distribution of resistance of codling moth to Cydia pomonella granulovirus in Europe

Thirty‐five codling moth (CM, Cydia pomonella L., Lepidoptera, Tortricidae) populations collected in different commercial orchards in six European countries were tested for their susceptibility to Cydia pomonella granulovirus (CpGV‐M). Including previously published data on CpGV‐M resistance, a total of 38 CM colonies showed considerably elevated LC₅₀ values, independent of the country origin. When only few test individuals are available, determination of mortality of neonate larvae at a discriminating concentration range of 10⁴ to 10⁶ OB/ml (>log4) as a direct measure of percentage susceptible individuals in a CM population is more advisable than calculation of LC₅₀ values. The >log4 mortality alone or in combination with the LC₅₀ value can be used for identification of resistance in a population. Results indicated a locally separated but widely spread occurrence of CM populations with low susceptibility to CpGV‐M. The most plausible hypothesis for the emergence of CpGV‐M resistance is its selection by repeated use of CpGV products.     

苹果蠹蛾颗粒体病毒CpGV-CJ01的分离和鉴定

苹果蠹蛾颗粒体病毒(Cydia pomonella granulovirus,CpGV)是控制苹果蠹蛾Cydia pomonella(L.)种群的重要生防因子。商业化产品病毒株单一,抗性的快速产生会降低CpGV的防效,高毒力或与之具有遗传差异的新病毒株可用于延缓病毒抗性的产生或发展,对苹果蠹蛾的控制策略具有重要作用。本研究从中国酒泉地区苹果园中的苹果蠹蛾野生种群及其实验室种群发病虫体中分离获得一株致病病毒,通过幼虫发病特征、病毒包涵体的形态学及分子生物学方法共同证实该病毒株为CpGV,且与CpGV-M相似,将其命名为CpGV-CJ01。其幼虫的发病体征具有CpGV感染的典型症状,包涵体的电镜形态学观察结果符合CpGV结构特征,利用分子生物学方法克隆得到Granulin基因和凋亡抑制蛋白基因(inhibitor of apoptosis protein,iap)均与CpGV-M具有99%以上的相似性,但是对于毒力的准确定量需要做进一步研究。我国新病毒株的发现为我国开展苹果蠹蛾颗粒体病毒的生物学防治创造了先决条件,并可作为延缓世界范围内CpGV抗性的候选菌株。     

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).     

Mobility of mass-reared diapaused and nondiapaused Cydia pomonella (Lepidoptera: Tortricidae): effect of different constant temperatures and lengths of cold storage

Desirable behavioral attributes in mass-reared insects should include the ability to perform favorably under the various environmental conditions they encounter upon release in the field. Insect quality also may be influenced by storage conditions and storage duration before field release. We studied the effects of three different constant ambient temperatures (15, 20, and 25 degrees C) and different lengths of adult cold storage (0, 24, 48, and 72 h at 2 degrees C) on the locomotor activity of adult Cydia pomonella (L.) mass reared through diapause or standard production protocols. Mobility was assessed in actographs housed in a climate controlled chamber; tests lasted 24 h. We found that adult mobility was significantly higher for both males and females at 25 and 20 degrees C than at 15 degrees C. There were no significant differences in mobility in moths reared through diapause or nondiapaused production protocols. In addition, temporal analysis of the data revealed a significant shift in the diel patterns of activity for both genders when adults were tested at the three different temperatures. Moths exposed to the lower temperature shifted their activity pattern from evening to mid-afternoon, which may be an adaptive behavior to take advantage of the expected warmest period of the day. Diapaused adults were significantly less mobile when stored in the cold (24, 48, or 72 h of storage at 2 degrees C) than were diapaused adults that did not experience cold storage (0 h). However, length of time in cold storage did not significantly influence the mobility of adult codling moths reared through standard production protocols.     

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.     

Is biofix necessary for predicting codling moth (Lepidoptera: Tortricidae) emergence in Washington State apple orchards?

The heat-driven phenology model used for initiating codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), management in Washington state was examined to determine the need for using the capture of the first moth as a method of synchronizing the model and phenology of field populations (= biofix). We examined trap catch data taken at 1-2-d intervals from two research orchards; one data set encompassed a 28-yr period and the other data set a 4-yr period. We also examined consultant-collected data taken at 7-10-d intervals from 15 sites (N = 81), mostly between 2001 and 2005. At the two research sites, we found the mean biofix occurred at 96 degree-days (DD) (DD Celsius by using 10 degrees C lower threshold and 31.1 degrees C horizontal upper threshold) after 1 January (SD = 14.4; min. = 68, max = 122). After correcting for longer sampling intervals in the consultant data set, the biofix at the nonresearch sites occurred at 97 DD (N = 50, SD = 14.4; min. = 74, max = 120), nearly identical to that at the research sites. We also examined the performance of the codling moth model at predicting moth flight and egg hatch using a biofix and by just accumulating heat units from 1 January. The model performance was similar in both generations regardless of whether a biofix was used. The elimination of biofix simplifies management and eliminates mistakes associated with poor trap catch, particularly in low-pressure situations where mating disruption reduces trap efficiency.