Verbenone Inhibits Attraction of Ips pini (Coleoptera: Curculionidae) to Pheromone-Baited Traps in Northern Arizona

Recent outbreaks of engraver beetles, Ips spp. De Geer (Coleoptera: Curculionidae; Scolytinae), in ponderosa pine, Pinus ponderosa var. scopulorum Engelm. (Pinales: Pinaceae), forests of northern Arizona have resulted in widespread tree mortality. Current treatment options, such as spraying individual P. ponderosa with insecticides or deep watering of P. ponderosa in urban and periurban settings, are limited in applicability and scale. Thinning stands to increase tree vigor is also recommended, but appropriate timing is crucial. Antiaggregation pheromones, widely used to protect high-value trees or areas against attacks by several species of Dendroctonus Erichson (Coleoptera: Curculionidae; Scolytinae), would provide a feasible alternative with less environmental impacts than current treatments. We evaluated the efficacy of the antiaggregation pheromone verbenone (4,6,6-trimethylbicyclo[3.1.1]hept-3-en-2-one) in reducing attraction of pine engraver, I. pini (Say), to funnel traps baited with their aggregation pheromone in two trapping assays. Treatments included 1) unbaited control, 2) aggregation pheromone (bait), 3) bait with verbenone deployed from a pouch, and 4) bait with verbenone deployed from a flowable and biodegradable formulation (SPLAT Verb, ISCA Technologies Inc., Riverside, CA). Unbaited traps caught no beetles. In both assays, baited traps caught significantly more I. pini than traps with either formulation of verbenone, and no significant difference was observed between the verbenone pouch and SPLAT Verb. In the second assay, we also examined responses of Temnochila chlorodia (Mannerheim) (Coleoptera: Trogositidae), a common bark beetle predator. Traps containing verbenone pouches caught significantly fewer T. chlorodia than the baited control and SPLAT Verb treatments. We conclude that verbenone shows promise for reducing tree mortality from I. pini.

Pine engraver beetle Ips acuminatus as a potential vector of Sphaeropsis sapinea

The pine engraver beetle Ips acuminatus Gyll. is a potential vector of the Sphaeropsis tip blight pathogen according to Leach’s postulates. The specimens of I. acuminatus were associated with numerous fungi species, namely Sphaeropsis sapinea (Fr.) Dyko & B. Sutton and ophiostomatoid species. The association between opportunistic pathogen S. sapinea and I. acuminatus has been confirmed for 62.9 % of all branches (44 % of needle samples and 82 % of wood samples). The presence of S. sapinea in the galleries and on the surface of the beetle indicates that I. acuminatus may transport the pathogen and later introduce it into healthy trees. The bark beetle can transfer pathogenic fungus during maturation feeding on the shoots of healthy pine crowns and into the branches during making galleries.

Retention Time in Three Nursery Container Volumes Impacts Root Architecture

Four general-use insecticides (Astro®, Onyx®, Dominion® Tree & Shrub, and Xytect 2F®) were evaluated for their effectiveness at preventing attacks by the southern pine beetle (SPB) (Dendroctonus frontalis) and the small southern pine engraver (Ips avulsus) using a previously developed small-bolt method. Evaluations were conducted between 58 and 126 days post treatment. Southern pine beetles from New Jersey and Mississippi, U.S., were evaluated using a mixture of field and laboratory small-bolt trials; beetle origin did not appear to affect results. Astro and Onyx bole sprays were effective at reducing or eliminating attack by SPB, while the imidacloprid soil drench products (Dominion and Xytect) were ineffective. With I. avulsus in Louisiana, U.S., Astro was effective at reducing bole utilization at 58 and 83 days posttreatment but failed at 126 days. Onyx, Dominion, and Xytect were ineffective against I. avulsus in these tests. Imidacloprid phloem residues averaged 0.74 (μg/g phloem dry weight) for Dominion and 1.31 for Xytect, values that are similar to other studies but low for purposes of control. These results support previous findings that systemic imidacloprid is ineffective for protecting pines against Dendroctonus bark beetles and that bole sprays with bifenthrin or permethrin can be effective. However, permethrin was the only active ingredient that was effective against I. avulsus in the current study.

Evaluation of General-Use Insecticides for Preventing Host Colonization by New Jersey Southern Pine Beetles

Four general-use insecticides (AstroR, OnyxR, DominionR Tree & Shrub, and Xytect 2FR) were evaluated for their effectiveness at preventing attacks by the southern pine beetle (SPB) (Dendroctonus frontalis) and the small southern pine engraver (Ips avulsus) using a previously developed small-bolt method. Evaluations were conducted between 58 and 126 days post treatment. Southern pine beetles from New Jersey and Mississippi, U.S., were evaluated using a mixture of field and laboratory small-bolt trials; beetle origin did not appear to affect results. Astro and Onyx bole sprays were effective at reducing or eliminating attack by SPB, while the imidacloprid soil drench products (Dominion and Xytect) were ineffective. With I. avulsus in Louisiana, U.S., Astro was effective at reducing bole utilization at 58 and 83 days posttreatment but failed at 126 days. Onyx, Dominion, and Xytect were ineffective against I. avulsus in these tests. Imidacloprid phloem residues averaged 0.74 (μg/g phloem dry weight) for Dominion and 1.31 for Xytect, values that are similar to other studies but low for purposes of control. These results support previous findings that systemic imidacloprid is ineffective for protecting pines against Dendroctonus bark beetles and that bole sprays with bifenthrin or permethrin can be effective. However, permethrin was the only active ingredient that was effective against I. avulsus in the current study.