Search

Novel methods of data analysis were used to interpret codling moth (Cydia pomonella) catch data from central-trap, multiple-release experiments using a standard codlemone-baited monitoring trap in commercial apple orchards not under mating disruption. The main objectives were to determine consistency and reliability for measures of: 1) the trapping radius, composed of the trap's behaviorally effective plume reach and the maximum dispersive distance of a responder population; and 2) the proportion of the population present in the trapping area that is caught. Two moth release designs were used: 1) moth releases at regular intervals in the four cardinal directions, and 2) evenly distributed moth releases across entire approximately 18-ha orchard blocks using both high and low codling moth populations. For both release designs, at high populations, the mean proportion catch was 0.01, and for the even release of low populations, that value was approximately 0.02. Mean maximum dispersive distance for released codling moth males was approximately 260 m. Behaviorally effective plume reach for the standard codling moth trap was<5 m, and total trapping area for a single trap was approximately 21 ha. These estimates were consistent across three growing seasons and are supported by extraordinarily high replication for this type of field experiment. Knowing the trapping area and mean proportion caught, catch number per single monitoring trap can be translated into absolute pest density using the equation: males per trapping area=catch per trapping area/proportion caught. Thus, catches of 1, 3, 10, and 30 codlingmothmales per trap translate to approximately 5, 14, 48, and 143males/ha, respectively, and reflect equal densities of females, because the codling moth sex ratio is 1:1. Combined with life-table data on codlingmoth fecundity andmortality, along with data on crop yield per trapping area, this fundamental knowledge of how to interpret catch numbers will enable pest managers to make considerably more precise projections of damage and therefore more precise and reliable decisions on whether insecticide applications are justified. The principles and methods established here for estimating absolute codling moth density may be broadly applicable to pests generally and thereby could set a new standard for integrated pestmanagement decisions based on trapping. [ABSTRACT FROM AUTHOR]

Three 'Red Delicious,' Malus domestica Borkhausen (Rosales: Rosaceae), apple plantings, each representing a different sport, were evaluated for natural resistance against the obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris). The establishment of neonate larvae on apple foliage was not different between the three 'Red Delicious' plantings. Of the three 'Red Delicious' plantings, the one that most negatively impacted OBLR was the 'It Delicious' genotype. The 'It Delicious' genotype at the Sunrise Research Orchard exhibited essentially 100% mortality against OBLR when fed on spring and summer foliage, and mortality accumulated faster across instars than on other 'Red Delicious' plantings. The high mortality observed in the 'It Delicious' genotype points to the existence of a putative gene, which we propose as Cro1. The other 'Red Delicious' plantings, Columbia River Orchard and Tree Fruit Research and Extension Center Research Orchard treatments, showed negative impacts, especially when exposed to foliage from the summer compared to the spring period. Development rates in these treatments in spring were higher compared to summer, and there were direct relationships between development rates, pupal weights, and adult longevity for both males and females. These latter results suggest that sublethal effects could be present in these 'Red Delicious' cultivars, thus offering insights to a gene-pyramiding strategy for breeders to managing leafroller pests in Washington apple., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The attraction of the stink bug Euschistus conspersus Uhler to sources of the synthetic pheromone component methyl (2E,4Z)-decadienoate was investigated in a series of field experiments in native vegetation surrounding commercial apple orchards in Washington. In experiments with pheromone lures placed inside two different tube-type traps, stink bugs were attracted to the immediate area around traps in large numbers, but very few were caught in the traps. Pheromone lures attached directly to the host plant mullein, Verbascum thapsus L., demonstrated that these 'baited" plants attracted significantly more E. conspersus than unbaited plants. Spring (reproductive) and summer (reproductively diapausing) E. conspersus adults, both males and females, were attracted to pheromone-baited plants. There was no significant difference in the number of male or female E. conspersus attracted to pheromone-baited traps or plants in any of the experiments, further characterizing methyl (2E,4Z)-decadienoate as an aggregation, and not a sex pheromone. Stink bug aggregations formed within 24-48 h of lure placement on mullein plants and remained constant until the lure was removed after which aggregations declined over 3-4 d to the level of unbaited plants. The implications of these studies for E. conspersus monitoring and management are discussed.

Pesticides were evaluated for their effect on two parasitoid species, Colpoclypeus flouts and Trichogramma platneri, that are potential biological control agents of leafrollers in apple orchards. Organophosphate and carbamate insecticides were highly toxic to both parasitoids in topical applications, but foliar residues of some products were nontoxic after 7 d. At reduced rates, topically applied pyrethroids were low in toxicity to C. florus were highly toxic to T. platneri, and foliar residues were nontoxic after about 7 d. Imidacloprid and abamectin were highly toxic when applied topically to both parasitoids but were not toxic as 1-d-old residues. Insect growth regulators did not cause mortality either as topical applications or residues; however, diflubenzuron caused severe sublethal effects, completely blocking the production of C. florus offspring. Biorational pesticides, such as soap, oil, and B. thuringiensis products, caused no toxicity to C. florus but had a direct impact on T. platneri as topical applications through physical immobilization. The potential to integrate different pesticides with biological control of leafrollers and the need for a step-wise approach to evaluate the impact of pesticides against natural enemies is discussed.

Campylomma verbasci Meyer is a zoophytophagous mirid that feeds on small arthropods as well as apple (Malus domestica Borkhausen) fruits, causing economic damage to some cultivars. The influence of timing and prey availability on the amount of fruit damage was studied to determine whether either factor could be used to refine a management program. C. verbasci nymphs were caged on branches of fruiting 'Golden Delicious' apple trees during the period from bloom through early fruit set. The greatest amount of fruit damage occurred during the bloom period; little or no damage occurred after fruit reached approximately equals 13 mm in diameter. The availability of prey did not reduce the incidence of fruit damage by C. verbasci, nor did it influence the survival of nymphs. Nymphal survival was higher, however, in cages where a blossom or fruitlet was present versus a vegetative spur. These data support the hypothesis that post petal fall insecticide applications (those made after the fruit is greater than approximately equals 10-13 mm in diameter) are not useful in preventing economic levels of fruit damage in Washington State, and that petal fall applications would only prevent a fraction of the total amount of damage by this pest. The data from this study do not support the hypothesis that manipulating arthropod prey species of C. verbasci will prevent fruit damage. There was evidence to support the hypothesis that nymphs can survive a relatively short period (7 d) without arthropod prey.