Identity and Seasonal Abundance of Beneficial Arthropods Associated with Big Sagebrush (Artemisia tridentata) in Central Washington State, USA.

Big sagebrush (Artemisia tridentata) characterizes and dominates the sagebrush steppe, the largest temperate semi-desert ecosystem in North America. The beneficial arthropod fauna hosted by A. tridentata is poorly known but could be of importance to nearby agriculture seeking to exploit biologically-based pest management. Over four years, we identified and assessed the seasonal abundance of beneficial arthropods (predators, parasitoids, pollinators) associated with A. tridentata during spring to autumn in the Yakima Valley of central Washington using sticky traps. During 2011⁻2014, 207 sticky traps were placed on non-blooming and blooming A. tridentata plants for a total of 966 trapping days. Overall, across all seasons, we trapped 259.7 beneficial arthropods per trap and 92% of these were parasitoid wasps. Significantly greater numbers of beneficial arthropods were associated with blooming A. tridentata during autumn (410/trap) than non-blooming plants in the spring (181.3/trap) or summer (85.1/trap). Parasitoid wasps and predatory true bugs were most abundant during the autumn, but ladybeetles, lacewings, spiders, bees, and predatory thrips were most common during spring. The association of high numbers of predators, parasitoids, and pollinators with A. tridentata during blooming and non-blooming periods indicates that this plant is an important reservoir of beneficial arthropods in the sagebrush steppe of central Washington. Consequently, biologically-based pest management programs in central Washington may benefit from careful management and retention of A. tridentata plants on crop borders.

Beneficial Insect Attraction to Milkweeds (Asclepias speciosa, Asclepias fascicularis) in Washington State, USA.

Native plant and beneficial insect associations are relatively unstudied yet are important in native habitat restoration programs for improving and sustaining conservation biological control of arthropod pests in agricultural crops. Milkweeds (Asclepias spp.) are currently the focus of restoration programs in the USA aimed at reversing a decline in populations of the milkweed-dependent monarch butterfly (Danaus plexippus); however, little is known of the benefits of these plants to other beneficial insects. Beneficial insects (predators, parasitoids, pollinators) attracted to two milkweed species (Asclepias speciosa, Asclepias fascicularis) in central Washington State, WA, USA were identified and counted on transparent sticky traps attached to blooms over five seasons. Combining all categories of beneficial insects, means of 128 and 126 insects per trap were recorded for A. speciosa and A. fascicularis, respectively. Predatory and parasitic flies dominated trap catches for A. speciosa while parasitic wasps were the most commonly trapped beneficial insects on A. fascicularis. Bees were trapped commonly on both species, especially A. speciosa with native bees trapped in significantly greater numbers than honey bees. Beneficial insect attraction to A. speciosa and A. fascicularis was substantial. Therefore, these plants are ideal candidates for habitat restoration, intended to enhance conservation biological control, and for pollinator conservation. In central Washington, milkweed restoration programs for enhancement of D. plexippus populations should also provide benefits for pest suppression and pollinator conservation.

Beneficial insects attracted to native flowering buckwheats (Eriogonum Michx) in central Washington.

Native plant and beneficial insect associations are relatively unstudied yet are important in native habitat restoration programs aimed at improving conservation biological control in perennial crops such as wine grapes. Beneficial insects (predators, parasitoids, pollinators) attracted to 10 species of flowering native wild buckwheat (Eriogonum spp.) in central Washington were identified and counted on transparent sticky traps. Combining all categories of beneficial insects, the mean number per trap ranged from 48.5 (Eriogonum umbellatum) to 167.7 (Eriogonum elatum). Three Eriogonum spp. (E. elatum, Eriogonum compositum, and Eriogonum niveum) attracted significantly more beneficial insects than the lowest-ranked species. E. niveum attracted greatest numbers of bees and parasitic wasps, and E. elatum was highly attractive to predatory true bugs and beneficial flies. Blooming periods of Eriogonum spp. extended from mid April to the end of September. This study demonstrates the attraction of beneficial insects to native flowering buckwheats and suggests their potential as a component of habitat restoration strategies to improve and sustain conservation biological control in Washington viticulture.