Resistance Affects the Field Performance of Insecticides Used for Control of Choristoneura rosaceana in Michigan Apples and Cherries

Field-based residual bioassays and residue analysis were conducted to assess the field performance and toxicity longevity of different insecticides that had previously been associated with resistance of Choristoneura rosaceana populations collected from apple and cherry orchards. In this study, 12–24 h-old larvae of apple and cherry populations were exposed to apple and cherry leaf samples, respectively, at post-application intervals and a susceptible population served as a reference of each. In the apple and cherry trials, the order of residual longevity of insecticides that effectively controlled the tested populations was as follows: bifenthrin and spinetoram (apple: 14, cherry 21-day post-application), phosmet (apple: 7, cherry 14-day post-application), chlorantraniliprole (apple: 7-day post-application), and indoxacarb and emamectin benzoate (apple: 1, cherry 7-day post-application). Compared to the susceptible population, the resistant populations resulted in a measurable loss of field performance, or “practical resistance”, for the insecticides emamectin benzoate (at 7-day post-application), chlorantraniliprole (at 21-day post-application), and indoxacarb (at all post-application intervals) in the apple trials, while in cherry trial just indoxacarb at 7-day post-application showed a reduced efficacy. In terms of long-lasting residues, only chlorantraniliprole and indoxacarb maintained measurable leaf residues over all post-application intervals while the leaf residues of the other compounds had largely degraded within the first 7 days. These findings can help fruit growers make adjustments to their spray/re-application intervals and optimally utilize important chemical tools in their integrated pest management programs.

Development of DNA Melt Curve Analysis for the Identification of Lepidopteran Pests in Almonds and Pistachios

Almonds and pistachios are fed upon by a diverse assemblage of lepidopteran insects, several of which are economically important pests. Unfortunately, identification of these pests can be difficult, as specimens are frequently damaged during collection, occur in traps with non-target species, and are morphologically similar up to their third instar. Here, we present a quantitative PCR based melt curve analysis for simple, rapid, and accurate identification of six lepidopteran pests of almonds and pistachios: navel orangeworm (Amyelois transitella), peach twig borer (Anarsia lineatella), oriental fruit moth (Grapholita molesta), obliquebanded leafroller (Choristoneura rosaceana), raisin moth (Cadra figulilella), and Indian meal moth (Plodia interpunctella). In this approach, the dissociation (melt) temperature(s) of a 658 bp section of cytochrome c oxidase subunit 1 was determined using quantitative PCR (qPCR). Within these six species, the distribution and the number of melt peak temperatures provide an unambiguous species level identification that is reproducible when unsheared DNA can be extracted. The test is robust across a variety of sampling approaches including insects removed from sticky card traps, museum specimens, and samples that were left in the field for up to 7 days. The melt curve’s simplicity allows it to be performed in any basic molecular biology laboratory with a quantitative PCR.

Attraction of Choristoneura Rosaceana (Lepidoptera: Tortricidae) to Pheromone Blends in Ratios Produced in Females’ Pheromone Gland or Emitted by the Females in Michigan Apple Orchards

Trap captures of obliquebanded leafroller, Choristoneura rosaceana (Harris) to pheromone blends in ratios approximating those reported in pheromone glands and a novel blend based on a volatile headspace collection from live virgin females were evaluated in field experiments in Michigan apple orchards. In an initial field trapping study, pheromone lures composed of either a three- or four-component blend approximation of the blend present in female pheromone glands at doses ranging from 0.1 to 20 mg/lure were compared. The four-component blend was a combination of (Z)-11-tetradecenyl acetate (Z11-14:Ac), (E)-11-tetradecenyl acetate (E11-14:Ac), (Z)-11-tetradecen-1-ol (Z11-14:OH), and (Z)-11-tetradecenal (Z11-14:Al) in a ratio of 96.5:1.8:1.4:0.2, respectively, while the three-component blend lacked Z11-14:Al. Pheromone emissions by groups of virgin females and commercial lures were collected in the laboratory and analyzed by gas chromatography. These data were used to formulate a new pheromone lure that was compared to a commercial lure in a second trapping study. In the first field study, traps baited with 10 mg pheromones or above captured significantly more moths than traps baited with 1 mg or less, regardless of the blend. Surprisingly, groups of virgin females only emitted two detectable pheromone components, Z11-14:Ac and Z11-14:OH in a ratio of 37:63 which was substantially different from the blends detected in pheromone glands in the literature. The newly formulated pheromone lure based on females’ emission was more than twice as attractive as the commercial lure which emitted a 74:5:21 three-component blend of Z11-14:Ac, E11-14:Ac, and Z11-14:OH, indicating that the response of C. rosaceana to its pheromone was more strongly mediated by the pheromone quantity relative to the blend ratio.

Modeling Climatic Influences on Three Parasitoids of Low-Density Spruce Budworm Populations. Part 2: Meteorus trachynotus (Hymenoptera: Braconidae)

This is the second article of a series of three where we develop temperature-driven models to describe the seasonal interactions between parasitoids and their hosts which we use to explore the impact of climate on their spatiotemporal biology. Here, we model the biology of Meteorus trachynotus (Hymenoptera: Braconidae) with an individual-based model of its daily interactions with two host species. This model predicts the performance of the parasitoid in response to temperature affecting its seasonal development and that of the two hosts. We compare model output with an extensive set of field observations from natural host populations. The predicted activity of the first adult parasitoid generation closely matches the seasonal pattern of attack on the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae) within the limitations of available data. The model predicts 1–4 full generations of M. trachynotus per year in eastern North America, with generations well synchronized with larvae of a known overwintering host, the obliquebanded leafroller Choristoneura rosaceana. The model predicts the observed density dependence of parasitism on spruce budworm. Predicted performance exhibits spatial variation caused by complex life-history interactions, especially synchrony with the overwintering host. This leads to a better performance in warm but not hot environments at middle latitudes and elevations. The model’s predicted spatial patterns correspond closely to our field observations on the frequency of parasitism on spruce budworm. Under climate change, the model predicts that the performance of M. trachynotus populations will improve in the northern portion of its range.

Managing orchard pests.

This chapter provides information on the various economically important insect and arthropod pests causing damage to cherry production, such as Rhagoletis indifferens, Drosophila suzukii, Choristoneura rosaceana, Tetranychus urticae and Caliroa cerasi, among others. Notes on their life cycle, damage and management methods are also presented.

Modeling Climatic Influences on Three Parasitoids of Low-Density Spruce Budworm Populations. Part 1: Tranosema rostrale (Hymenoptera: Ichneumonidae)

Despite their importance as mortality factors of many insects, the detailed biology and ecology of parasitoids often remain unknown. To gain insights into the spatiotemporal biology of insect parasitoids in interaction with their hosts, modeling of temperature-dependent development, reproduction, and survival is a powerful tool. In this first article of a series of three, we modeled the biology of Tranosema rostrale at the seasonal level with a three-species individual-based model that took into account the temperature-dependent performance of the parasitoid and two of its hosts. The predicted activity of the first adult parasitoid generation closely matched the seasonal pattern of attack on the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae). The model predicted 1–4 full generations of T. rostrale per year in eastern North America. The generations were generally well synchronized with the occurrence of larvae of a probable alternate host, the obliquebanded leafroller Choristoneura rosaceana (Lepidoptera: Tortricidae), which could be used as an overwintering host. Spatial differences in predicted performance were caused by complex interactions of life-history traits and synchrony with the overwintering host, which led to a better overall performance in environments at higher elevations or along the coasts. Under a climate warming scenario, regions of higher T. rostrale performance were predicted to generally move northward, making especially lower elevations in the southern range less suitable.

The Chimeric Bud-Sport ‘Delicious’ (Red) Mutant Strain, It, Expresses Lethal-Effect Resistance Against the Obliquebanded Leafroller (Lepidoptera: Tortricidae)

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.

Parasitoid guild and parasitism rate of the obliquebanded leafroller in IPM orchards and adjacent woodlands

The obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris) [Lepidoptera: Tortricidae], a primary pest in Quebec apple orchards, can be naturally parasitized. Knowing that habitats around crop’s peripheries are reservoirs for natural enemies of pests, the objective of the present investigation was to assess parasitism and parasitoid guild composition associated with the OBLR. The two-year study included orchards under integrated pest management, their edges, and adjacent woodlands. Parasitism was assessed using sentinel OBLR larvae and considered spring, early summer and late summer. Parasitism rates between regions with different vegetation composition were not significantly different. The first year, late summer larvae showed higher parasitism in orchards (27%), compared to edges (7%) and woodlands (11%). The following year, larvae exposed in early summer had higher parasitism rate in edges (28%) compared to orchards and woodlands (17% in both zones). Nineteen parasitoid species parasitized sentinel larvae. The tachinid Actia interrupta (Curran), the most abundant species, represented 28 and 62% of species the first and the second year respectively. Our research demonstrates that natural biological regulation of the OBLR is the result of a highly diversified parasitoid guild and this should be taken into account in any Integrated Pest Management program.