A granulosis virus,possible biological agent for control ofAdoxophyes orana (Lepidoptera: Tortricidae) in apple orchards

Based on the results of ecological surveys of Adoxophyes orana and its natural enemies in apple orchards sprayed with the granulosis virus and control plots, we constructed working models to simulate the population dynamics in three different experimental plots; those treated with chemical insecticides, those with granulosis virus, and controls. The number of individuals killed by predators, parasitoids and by miscellaneous mortality factors could be calculated on the assumption of imperfect density relations; that is, relation of the number killed by each factor with the initial number of larvae was represented by a curve with an upper asymptote. We could estimate the proportion of virus infection using curves with upper asymptotes. Rate of increase from pupa to middle instar larvae of the next generation was subject to strong density-effect. Simulation we proposed in this paper suggests a possibility that a single spray of the virus at 1st generation can reduce not only the number of A. orana larvae in the 2nd and 3rd generations but also the degree of fruits injured by this insect. Spray of chemical insecticide is considered to be ineffective in reducing the pest density and the degree of injury to low levels in subsequent generations, as compared with untreated plot, where the density of the 1st generation larvae is low.     

Integrated control of apple pests in New Zealand 10. Population dynamics of codling moth in Nelson

Abstract

Sampling methods are described for estimating the population density, mortality, and natality of a univoltine population of codling moth attacking mature apple trees (cv. ‘Delicious’) at Nelson, New Zealand. These methods were used to construct life tables for the species over eight generations (1967–68 to 1974–75) on trees variously sprayed and not sprayed with ryania in an integrated control programme. Bait traps provided a sensitive measure of seasonal adult population density. Analysis of the life tables shows that migration of adults was the main key factor and that overwintering larval mortality (particularly that due to bird predation), fecundity, and ryania also made a major contribution to variation in generation mortality. In the absence of ryania the resident population usually increased between generations, whereas it usually decreased when ryania sprays were applied. The density dependence of overwintering larval mortality was due to bird predation, and the inverse density dependence of larval mortality from ryania was due to changes in the site of fruit entry with larval population density. Fecundity was density independent, and inconclusive evidence was obtained on the density dependence of migration. The wide variation in fecundity is attributed primarily to weather conditions. The impact on control strategy of the above key factors, density dependence, and total natural mortality is discussed. Ryania is found to be uneconomic, whereas the granulosis virus of codling moth and male removal with pheromone traps show promise as future control methods. The need to eliminate reservoirs of codling moth close to orchards under integrated pest control is emphasised. Regulation of codling moth populations at Nelson on neglected, unsprayed trees appears to result from intraspecific competition for fruits and cocooning sites, and weakly density-dependent mortality of mature larvae when seeking cocooning sites and while overwintering in their cocoons. Variation in fecundity also cohtributes to fluctuations in abundance of the species. In contrast, at low density in an integrated control programme no intraspecific competition was evident; migration, winter mortality, and fecundity were the main determinants of abundance. This illustrates the need to study pest populations at densities similar to those tolerable commercially.     

A granulosis virus,possible biological agent for control of Adoxophyes orana (Lepidoptera: Tortricidae) in apple orchards: I. Mass production

Young larvae of Adoxophyes orana (apple race) were infected with a granulosis virus by feeding them artificial diet containing the virus suspension. The susceptibility decreased remarkably after the fourth to fifth instar. Infected larvae survived the end of the fifth (last) instar, even when they were infected at an early developmental stage. Inoculation of egg masses by dipping them into a virus suspension gave a high percentage of infection when larvae were reared en masse.     

Mass production and utilization ofTrichogramma: 10. Control of the codling mothCydia pomonella and the summer fruit tortrix mothAdoxophyes orana [Lep.: Tortricidae]

The effectiveness ofTrichogramma dendrolimi, Trichogramma embryophagum, Trichogramma sp. strain 45 andTrichogramma sp. strain 48 to control the codling mothCydia pomonella L. and the summer fruit tortrix mothAdoxophyes orana F.R. was tested in 4 field trials (1984–1986). Four to sixTrichogramma treatments (depending on the temperature) each at 400 (pillar trees) to 9,000 (round tops) parasites per tree were carried out between June and August to insure the continuous presence ofTrichogramma in the plots. The monitoring was done by examining 3,000 to 10,000 apple fruits per plot. T. dendrolimi reduced the damage ofC. pomonella by 61.35%, ofA. orana by 72.85%.T. embryophagum reduced the damage ofC. pomonella by 50.06%, ofA. orana by 50.8%.Trichogramma strain 45 reduced the damage ofC. pomonella by 41.6% and ofA. orana by 87.9%,Trichogramma strain 48 by 57.2% and 51.2% respectively. The reduction of 67.1% in the number of apple fruits damaged byC. pomonella andA. orana obtained by the inundative releases ofT. dendrolimi in these experiments is considered economically and the use of this species in practice is recommended.      

Aerial application of mixed virus formulations to control joint infestations of Panolis flammea and Neodiprion sertifer on lodgepole pine

An aerial spray using mixed formulations of two viruses, Panolis flammea nuclear polyhedrosis virus (NPV) and Neodiprion sertifer NPV was conducted against mixed populations of the two pests, P. flammea and N. sertifer on lodgepole pine. These were compared with single virus formulations sprayed against their respective host pests and an unsprayed control. One hectare plots of 14 yr old pine were sprayed by helicopter using ultra low volume techniques. Larvae from each plot were assessed weekly for virus and this showed that the mixed formulations gave the same level of control as separate applications of each NPV. Levels of infection in P. flammea reached 95 – 100% 9 wk post-spray, and in N. sertifer reached 100% 6 wk post-spray. Later P. flammea pupal sampling showed no viral infection in the control but significant levels in sprayed plots, which ranged from 37–9% in the plot sprayed with the high dose of N. sertifer NPV to 75% in the plot sprayed with the low dose of NsNPV.     

Unmown groundcover conserves adult populations of the predatory ground beetle Chlaenius micans (Coleoptera: Carabidae) in commercial apple orchards

To improve the success of integrated pest management in commercial apple orchards, I investigated whether the use of unmown white clover groundcover would enhance the numbers of a predatory ground beetle, Chlaenius micans (Fabricius), relative to mowing. From 2009 to 2011, narrow-spectrum insecticides were sprayed in one apple orchard and broad-spectrum insecticides in another in Akita Prefecture, northern Japan. Half of each orchard was plowed and sown to white clover in mid-April 2009; subsequently, these plots were not mowed and herbicides were not applied. The other half of each orchard was mowed every 3 weeks from mid-May to late August each year, and herbicides were sprayed around trees in mid-June. Significantly more adult Ch. micans were captured in pitfall traps in the unmown clover plots than in the mown plots. Thus, the retention of unmown groundcover increased the populations of adult Ch. micans in apple orchards.     

Pheromone trap and population model-based control of the codling moth, Cydia pomonella L., in Romanian apple culture

Like in most parts of the world, the codling moth, Cydia pomonello (L.), is one of the most important pests in apple orchards in the Romanian Banat region. There, the control of this pest is often inadequate and the damage and economic losses are therefore enormous. This lack of control is caused by structural problems such as the absence of an advanced distribution network for phytopharmaceutical products, obsolete spraying equipment and the insufficient exchange of knowledge and expertise of those products and the pest itself between the local research facilities and the apple growers. The purpose of this research project is rather demonstrative, because a change in the Romanian pome culture's attitude is urgently needed. Pheromone trapping and the computerized population model RIMpro Cydia, which predicts important phenological events such as adult flight and egg hatch, were used to determine the optimal spray timing. These modern pest management techniques would not only minimize pressure on the environment, but also on the income of the Romanian apple grower, for whom phytopharmaceuticals are a high-priced investment. In July 2006 a comparative study between the supervised pest control program using Calypso, Runner and Reldan, all easily obtainable and commercially available insecticides in the region, and a conventional Romanian management programme was conducted. The control plot and the two test plots were all three located in a high codling moth pressure orchard in Timi?oara. In the control plot 9,44 % of the fruits were damaged by codling moth larvae. In the plot containing the trees that were treated according to the traditional Romanian management programme 5,56 % damage was recorded, while the supervised management plot showed only 1,1% damage. Additionally damage was measured in another orchard in Periam, about 60 km away from the other plots. There, an intensive control program using Reldan, Calypso, Actare, Karate and Insegar was applied and damage measured only 0.2%. While at first glance that approach seems most efficient, it has to be noticed that it used twice as much insecticide treatments as were used in the supervised control program. Furthermore, 1 % damage is suggested by most references as being the economical threshold for treatments. The results of this comparative study clearly show that supervised codling moth control proofs to be the most profitable. Starting from August the same year, all of the control programmes in Timi?oara were stopped. Therefore the second and possibly the third generation of codling moth larvae could develop freely. In the plot which was earlier sprayed according to the warnings of RIMpro Cydia and the pheromone trap this resulted in 27.5% damaged fruits during harvest in September. In the control plot damage reached 60.95%. These results highlight the necessity of the development of an efficient codling moth control program. Once that program is fine-tuned it should be presented to the local apple growers in order to give the Romanian pome culture a boost.     

Biocontrol of moth pests in apple orchards: Preliminary field study of application potential for mass trapping

Many moth pheromones and synthetic attractants have been used to monitor or decrease pest populations. However, due to their low economic efficiencies and narrow target specificities these methods are of limited use for trapping pests in large agricultural fields. In an effort to address this problem, we selected oak (Quercus serrata) sawdust media fermented by the yeast strain Pichia anomala, and examined its ability to attract lepidopteran moth pests for mass trapping in an apple (Malus domestica) orchard. A total of 57 taxa were trapped, including 42 species of lepidopteran pests. The most frequently caught lepidopteran pests included Adoxophyes orana (40.0 ± 3.5 individuals/trap/week), Oraesia excavata (35.5 ± 2.5), and Adris tyrannus amurensis (35.5 ± 2.5). Notably, less fruit damage was recorded in the experimental orchard versus a trap-free neighboring control orchard. These results suggest that adult moths might be effectively attracted and mass captured using P. anomala-fermented oak sawdust media as bait.     

Genetics of resistance in apple against <Emphasis Type="Italic">Venturia inaequalis</Emphasis> (Wint.) Cke

Apple (Malus × domestica) is the third important fruit in terms of production and consumption worldwide. Apple scab caused by Venturia inaequalis is the most devastating disease of apple. In the apple-growing regions, many fungicides are sprayed to control the disease leading to increase in the production cost. Development of scab-resistant cultivars is the long-lasting solution to control the disease. In apples, more than 20 major scab resistance genes have been identified in various cultivars and few wild relatives. Of all these genes, Rvi6 derived from Malus floribunda has been most extensively used in different breeding programs. Gene for gene interactions of these resistance genes with the avirulence genes from V. inaequalis have been understood in many cases. QTL-based polygenic resistance has also been characterized in apple. Nucleotide Binding Site Leucine-Rich Repeats (NBS-LRR) have been identified from the apple genome and many of them have been characterized from the scab resistance region. Molecular markers associated with most of the major scab resistance genes have been identified and their position has been mapped on different linkage groups. Marker-assisted selection (MAS) can be helpful in speeding up and accurately identifying the scab-resistant parents and progeny. Pyramiding of several major resistance genes can be undertaken for more durable resistance against apple scab. The present paper reviews the Malus-Venturia pathosystem, current status of knowledge about scab resistance genes, and their application in breeding against apple scab.     

Pouteria caimito fruit derived nanoparticles inhibited the apple ring rot disease as well as extended the shelf-life of sliced apples

BackgroundApple disease, exaggerated by Botryosphaeria dothidea, is a foremost intimidating problem for extending the apple fruit shelf-life and producing substantial economic losses for cultivators and distributors. Alternate sources are urgently needed to prevent or inhibit the ring rot infection of apple fruit instigated by Botryosphaeria dothideaObjectiveIn this current study, we premeditated to make novel organic nanoparticles as of Pouteria caimito fruit extract and calcium chloride (PCNP), which were used to evaluate the preventive outcome of Botryosphaeria dothidea-caused apple disease on postharvest apple fruits.ResultsOur findings corroborated that the fruit derived nanoparticle had been confirmed for quality and size by altered estimations such as fourier transform infrared (FTIR), UV–vis spectroscopic analysis, scanning electron microscope and energy dispersive X-ray (SEM and EDX) estimation, and dynamic light scattering (DLS) analysis. In addition, we have investigated the excellent inhibitory action of the pathogen infection in apples initiated by Botryosphaeria dothidea. The protective enzymes function was pointedly improved in nanoparticle-treated apple fruits once equated with those of control apple fruits. The catalase (CAT) and superoxide dismutase (SOD) activities were pointedly improved in nanoparticle-treated fruits when compared to those of control fruits. The shelf-life extension studies were conducted for 7 days with a fresh-cut apple. The total soluble solid, pH, weight loss, and sensory studies were analyzed, and they proved the extension of sliced apple shelf life up to 7 days.ConclusionsThe discoveries of this study provided a well-organized, harmless, and environment-friendly substitute to control the apple disease as well as the durability postponement of sliced apples 7 days or may longer.     

The effect of the granulovirus (PapyGV) on larval mortality and feeding behaviour of the Pandemis leafroller,Pandemis pyrusana (Lepidoptera: Tortricidae)

An indigenous betabaculovirus (PapyGV) of the Pandemis leafroller, Pandemis pyrusana (Kearfott), was studied in the laboratory and greenhouse to determine how the virus affected leafroller mortality and foliar damage. Probability of mortality increased with virus concentration as observed after 7 and 10 days of feeding on virus treated diet in neonates and second instar larvae. LC₅₀ estimates for neonates at 7 and 10 days was 2743 and 389 occlusion bodies (OBs)/mm². For second instars, LC₅₀ was 139,487 and 813 OBs/mm² at 7 and 10 days. There was no biologically significant mortality response to increasing virus concentrations by fourth instar larvae; however, when fourth instar larvae were infected with virus on diet and then fed apple leaves, the leaf area consumed declined up to 50% with higher virus concentrations. In a greenhouse study, neonate larvae that fed on seedlings treated with water showed >90% survival and 80% pupation rate of larvae after being transferred to diet. In contrast, larvae that fed on apple seedlings sprayed with 3×10⁶ OBs/ml showed poor survival when transferred to diet after acquiring the virus and failed to reach the pupal stage. This virus shows promise for population regulation and can produce reduction in feeding damage.     

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).     

MdVHP1 encodes an apple vacuolar H(+)-PPase and enhances stress tolerance in transgenic apple callus and tomato

Vacuolar H⁺-translocating inorganic pyrophosphatase (VHP, EC 3.6.1.1) is an electrogenic proton pump, which is related to growth as well as abiotic stress tolerance in plants. In this study, a VHP gene MdVHP1 was isolated from apple. The alignment of nucleotide and amino acid sequences showed that it encoded a type I VHP protein. It expressed in vegetative and reproductive organs, and its expression was induced by salt, PEG-mediated osmotic stress, cold and heat in apple in vitro shoot cultures. MdVHP1 expression showed a similar pattern in different apple tissues, but different change dynamics in response to abiotic stresses, compared with MdVHP2 (another MdVHP gene in apple). MdVHP1 overexpression enhanced tolerance to salt, PEG-mimic drought, cold and heat in transgenic apple calluses, which was related to an increased accumulation of proline and decreased MDA content compared with control calluses. In addition, MdVHP1 overexpression confers improved tolerance to salt and drought in transgenic tomato, along with an increased ion accumulation, high RWC and low solute potential compared with wild type. These results indicate that MdVHP1 is an important regulator for plant tolerance to abiotic stresses by modulating internal stores of ions and solutes.     

The effect of carbamide and thiocarbamide on the resistance of apple to apple scab

Carbamide and thiocarbamide decreased the resistance of apple to apple scab when infiltrated into apple leaves prior to infection with the disease. In three apple varieties these two substances strikingly stimulated infection with two monosporic isolates of the fungusVenturia inaequalis (Cke.) Wint. It was established that both carbamide and thiocarbamide inhibited polyphenol oxidase activity in apple leavesin vivo, butin vitro only thiocarbamide was inhibitory. It can be concluded that the effect on apple resistance to apple scab is based on an inhibition of polyphenol oxidase.     

Activation of latent virus infections in larvae of Adoxophyes orana (Lepidoptera: Tortricidae) and Barathra brassicae (Lepidoptera: Noctuidae) by foreign polyhedra

The number of larvae containing polyhedra increased when larvae of Adoxophyes orana and Barathra brassicae were fed on polyhedra of nuclear polyhedrosis virus (NPV) of the reciprocal species. Comparison of restriction endonuclease EcoRI cleavage patterns of DNA isolated from polyhedra used as inocula and from polyhedra obtained after cross-inoculation showed that cross infection did not occur. The observations indicate that latent viruses were activated in both insects. Activation of the A. orana latent NPV with polyhedra of a cytoplasmic polyhedrosis virus (CPV) of B. brassicae, and cross-inoculation with an extract prepared from healthy larvae indicated that an activating agent does not have to be a component of nuclear polyhedra.     

Bacillus amyloliquefaciens GB1 can effectively control apple valsa canker

Apple valsa canker (AVC), caused by Valsa mali, is one of the most serious diseases of apple trees in eastern Asia, and the most important factor limiting apple production in China. This disease is difficult to control by chemical and agricultural measures, thus biocontrol may constitute a desirable alternative strategy. A Bacillus amyloliquefaciens strain denoted GB1 isolated from ageing cucumber stems, exhibited a strong antagonistic activity against V. mali, inhibiting significantly the germination of conidia and the growth of hyphae. GB1 conidial suspensions (above 10⁶ CFU/ml) applied prior to wound inoculation of apple twigs with V. mali resulted in total inhibition of infection. Strain GB1 colonized xylem and phloem tissues surrounding the wounds made on apple twigs and formed biofilms over them. Results indicate that B. amyloliquefaciens GB1 may be a promising agent for the biocontrol of AVC, and provide new insights into the ability of B. amyloliquefaciens to colonize apple trees.     

Effect of native natural enemies on the population dynamics of the grape mealybug,Pseudococcus maritimus (Hom.: Pseudococcidae), in apple and pear orchards

The impact of native natural enemies on populations of the grape mealybug,Pseudococcus maritimus (Ehrhorn) in apple and pear orchards was assessed using a combination of techniques, including exclusion cages, limb-banding, and visual inspection of shoots and fruits. The complex of native natural enemies (which included two encyrtid parasitoids, (Pseudaphycus websteri Timberlake andMayridia species), a coccinellid beetle (Hyperaspis lateralis Mulsant), and a chamaemyiid fly (Leucopis verticalis Malloch), provided reasonably good control in orchards that had not been treated with insecticides for one to two years. However, surveys indicated that most of these species were absent from orchards regularly sprayed with pesticides.     

Fitness-related traits of entomopoxviruses isolated from Adoxophyes honmai (Lepidoptera: Tortricidae) at three localities in Japan

Three entomopoxviruses (EPVs) isolated from diseased Adoxophyes honmai larvae at different localities (Tsukuba, Itsukaichi, and Miyazaki) in Japan were compared for biochemical identity and key parameters of virus fitness, fatal infection, speed of kill, and virus yield. When the structural peptides of occlusion bodies (OBs) and occlusion-derived viral particles were compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, no difference in banding patterns was observed. However, DNA restriction endonuclease analysis showed that the three isolates were genotypically different, but many commonly sized DNA fragments were observed. Five tortricid species, A. honmai, Adoxophyes orana, Adoxophyesdubia, Homona magnanima, and Archips insulanus were susceptible to all isolates. No significant differences in the key viral fitness parameters were detected among the isolates in A. orana. However, the Miyazaki isolate had a different effect on H. magnanima; it allowed infected insects to survive longer and develop to a larger size, but had a lower yield of OBs per larva at any given time to death. OB yields per unit cadaver weight for the Miyazaki isolate, which indicate the conversion rate of the insect to virus, were lower over time compared to the other two isolates. The implications for selecting a candidate isolate to control tortricid pests are discussed.     

Management of apple scab (Venturia inaequalis) in Romania based on electronic warnings

Apple scab, Venturia inaequalis (Cke) Wint., is a major problem in Romanian apple orchards and is responsible for serious economic losses. The purchase of spraying equipment and phytopharmaceutical products is very expensive in comparison to the income of local apple growers. This is one of the reasons why reduced fungicide sprayings are becoming more and more important. That's why a project was started to investigate the influence of West-European control measures and to improve interaction between local apple growers and research facilities. This experiment took place in an orchard of the university of Timisoara (USABT), where occurrence of apple scab was very high, and in a well managed commercial orchard, both in the Banat region. In July 2006, a comparative study between a traditional Romanian management program, a calendar-based program and a computerized weather-based management program was conducted. Four test plots were taken. The sprayments in plot 1 happened according to the integrated computerized model. No sprayings took place in plot 2. In plot 3 were some sprayments done with sulphur according to the traditional Romanian program. The sprayings in plot 4 were done following a calendar-based spraying program. The products that were used for the sprayments were all easy to obtain in Romania such as dodine (Sillit flow), dithianon (Delan flow), difenoconazole (Score), pyrimethanil (Scala), metiram (Polyram), kresoxim-methyl (Stroby). The occurrence of scab in plot 1 was very low in comparison to the other plots. Analysing the data, on average, the treatments done in plot 1 caused about 50% less damage than the traditional sprayings. This indicated that with a relative small amount of well timed sprayings a enormous amount of damage can be prevented. A calendar-based management program seems to be less effective (more sprayings needed and the results are worse). These results also emphasize the importance of the development of an adequate apple scab management program that should be presented to local apple growers.     

Peripheral-zone treatments for plum curculio management: validation in commercial apple orchards

A field trial was conducted using an oil formulation of the entomopathogenic fungus, Metarhizium flavoviride Gams & Rozyspal (Deuteromycotina: Hyphomycetes), to control the variegated grasshopper, Zonocerus variegatus L. (Orthoptera: Pyrgomorphidae). The influence of dispersal and secondary pick-up from the spray residue on mortality was assessed by sampling insects from the treated plots at intervals and monitoring disease levels during subsequent incubation in the laboratory. The cumulative mortality curves showed the pathogen to be highly effective, even in samples taken 8 days after spraying. A model was developed to link the influence of mortality, incubation, secondary pick-up of spores and insect dispersal, on the shape of these cumulative mortality curves. The model proved useful for data received from an experiment using small plot sizes, where insect dispersal is a big problem. The spray residue had an important influence on overall insect mortality. The model also indicated a difference in speed of kill between field and laboratory samples, suggesting an incubation delay in the field.