Interruption of the semiochemical-based attraction of ambrosia beetles to ethanol-baited traps and ethanol-injected trap trees by verbenone.

We examined the extent to which verbenone, a bark beetle antiaggregation pheromone, interrupted the semiochemical-based attraction of ambrosia beetles. Field trapping studies conducted in Ohio showed that a verbenone dispenser with a release rate of 50 mg/d at 25°C reduced the attraction of Anisandrus sayi Hopkins, Euwallacea validus (Eichhoff), Hypothenemus dissimilis (Zimmermann), Xylosandrus germanus (Blandford), and Xyleborinus saxesenii (Ratzeburg) to ethanol-baited traps. A verbenone dispenser attached to ethanol-injected Magnolia virginiana L. trap trees deployed in Ohio also reduced ambrosia beetle attacks compared to trap trees without a verbenone dispenser. Subsequent field trials demonstrated a direct relationship between distance from a verbenone dispenser and ambrosia beetle attacks on trap trees in Ohio in 2011 and 2012 and Tennessee in 2012, but not in Tennessee and Virginia in 2011. Assessment of the influence of verbenone on the probability of attacks above a density threshold found that although attacks occurred on trap trees regardless of their proximity to a verbenone dispenser, the higher density of attacks per tree occurred on trap trees farthest away from the verbenone source in Ohio and Tennessee. Verbenone alone could be somewhat useful for discouraging ambrosia beetle attacks on individual trees or on a small spatial scale, but deployment of verbenone might be most effective when integrated as part of a "push-pull" strategy.

Systemic insecticides for control of black vine weevil (Coleoptera: Curculionidae) in container- and field-grown nursery crops.

Black vine weevils, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae), are serious pests of container- and field-grown nursery crops. Management programs usually target the larval stage in container-grown plants and the adults in field-grown plants. We tested several new systemic insecticides for efficacy against black vine weevil in container-grown Sedum spp. and field-grown Taxus spp. In 2006 and 2007, clothianidin, dinotefuran, and chlorantraniliprole were applied as surface drenches to containerized Sedum plants, and suppression of larval densities and adult feeding were evaluated. Sedum leaf bioassays were used to further examine the influence of clothianidin, dinotefuran, and chlorantraniliprole on adult feeding. In 2006, pots were infested with adult black vine weevil 1 d after treating, and in 2007 pots were infested 1 or 43 d after treating. All three insecticides significantly reduced the numbers of larvae in 2006, but not in 2007, because of low numbers of larvae in the untreated control plants. Dinotefuran and clothianidin reduced feeding by adult black vine weevil on containerized Sedum plants, resulting in more blossoms, fewer damaged leaves, and a lower percentage of leaves damaged compared with control plants. In bioassays with detached leaves, all three insecticides reduced feeding compared with control plants. Efficacy and timing of clothianidin, imidacloprid, and acephate soil drenches and imidacloprid and acephate soil injections were evaluated for black vine weevil control over a 1-yr period in field-grown Taxus plants. All insecticide treatments significantly reduced the numbers of larvae in field-grown Taxus plants compared with control plants; and all but the spring acephate drench improved the appearance of the Taxus (foliar rating) plants compared with untreated plants. All of the tested insecticides showed potential for preventing infestations of black vine weevil larvae and reducing feeding by the adults in ornamental plants.

Intra- and interspecific interactions between Lysiphlebus testaceipes and Lipolexis scutellaris (Hymenoptera: Aphidiidae) reared on Toxoptera citricida (Homoptera: Aphididae).

Classical biological control of the brown citrus aphid Toxoptera citricida Kirkaldy in Florida has involved the release of Lipolexis scutellaris Mackauer. Lysiphlebus testaceipes Cresson is already present in Florida and also parasitizes T. citricida. Because parasitoid-parasitoid interactions may affect the establishment of a newly introduced parasitoid species, intra- and interspecific larval interactions of both parasitoids were studied in the laboratory using T. citricida reared on citrus. Five time intervals were allowed between successive oviposition opportunities. Early developmental times were determined for both parasitoids: eggs of L. testaceipes and L. scutellaris hatched after 54.3 and 61.7 h, while molt to second instar occurred after 73.3 and 87.1 h, respectively, after oviposition at 22 degrees C. At intervals <12 h, both parasitoids had a greater tendency to multiparasitize than to superparasitize, and the tendency to superparasitize or multiparasitize decreased with an increase in time between successive oviposition opportunities. Of the 10 interspecific interactions studied, 5 produced a winning wasp species, 3 of which could be explained by the hypothesis of physical conflict. A combination of development time, age of competing larvae, and oviposition sequence were responsible for the outcomes observed. Neither parasitoid proved to be intrinsically superior when interspecific competition occurs in second- and third-instar T. citricida, indicating there is no reason to suggest that they cannot coexist in Florida citrus groves.