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.

Phenology of semiochemical-mediated host foraging by the western boxelder bug, Boisea rubrolineata, an aposematic seed predator.

The western boxelder bug (BEB), Boisea rubrolineata (Heteroptera: Rhopalidae), is a specialist herbivore of boxelder trees, Acer negundo. We tested the hypothesis that BEBs use semiochemicals to locate host trees. Headspace volatiles from trees bearing staminate inflorescences ("staminate trees") and from trees bearing pistillate inflorescences ("pistillate trees") were collected throughout the season and bioassayed in Y-tube olfactometer experiments. Headspace extracts of early-season, pollen-bearing staminate trees and midseason pistillate trees with mature samaras (seed pods) attracted female and male BEBs. By using coupled gas chromatographic-electroantennographic detection and gas chromatography-mass spectrometry, we identified and tested a five-component synthetic blend of candidate semiochemicals (hexanol, pentyl acetate, phenylacetonitrile, 2-phenethyl acetate, and trans-nerolidol). This blend attracted females, males, and fifth-instar nymphs. Phenylacetonitrile by itself was as attractive as the five-component blend to both adults and nymphs. By responding to phenylacetonitrile emitted by pollen-bearing staminate trees and pistillate trees with maturing seeds, BEBs appear to track and exploit the availability of nutrient-rich food sources, suggesting that the bugs' reproductive ecology is synchronized to the phenology of their host boxelder tree.

Infrared radiation from hot cones on cool conifers attracts seed-feeding insects.

Foraging animals use diverse cues to locate resources. Common foraging cues have visual, auditory, olfactory, tactile or gustatory characteristics. Here, we show a foraging herbivore using infrared (IR) radiation from living plants as a host-finding cue. We present data revealing that (i) conifer cones are warmer and emit more near-, mid- and long-range IR radiation than needles, (ii) cone-feeding western conifer seed bugs, Leptoglossus occidentalis (Hemiptera: Coreidae), possess IR receptive organs and orient towards experimental IR cues, and (iii) occlusion of the insects' IR receptors impairs IR perception. The conifers' cost of attracting cone-feeding insects may be offset by occasional mast seeding resulting in cone crops too large to be effectively exploited by herbivores.