Experiments were conducted near Williams Lake and Quesnel, BC in 2003 to evaluate the effectiveness of the antiaggregation pheromone verbenone and a three-component non-host volatile (NHV) blend (E-2-and Z-3-hexen-1-ol and benzyl alcohol) in deterring attack of lodgepole pines, Pinus contorta var. latifolia Engelmann, by the mountain pine beetle, Dendroctonus ponderosae Hopkins. In 0.16-ha square plots, with a pheromone-baited tree in the centre and 16 release points at 10-m centres, either verbenone (in a polyurethane gel inside plastic membrane pouches, released at ca. 100 mg/day) or the NHVs (released from separate bubble caps at ca. 1.2 mg/day) deterred attack, but efficacy was not increased by combining them. When deployed from 25 release points at 10-m centres in 0.25-ha square plots, verbenone plus NHVs were effective in deterring attack in some (but not all) cases, when compared to attack in a 25-m wide band around the treated zone. In a test of the push-pull tactic, verbenone plus the NHV blend were tested in a 10-replicate experiment with 100, 44.4 or 25 release points/ha at 10-, 15-or 20-m centres, respectively, in a 1-ha square central zone surrounded by a 3-ha, 50-m-wide band containing 12 pheromone-baited lodgepole pines 50 m apart. Other treatments were pheromonebaited trees alone, and an untreated control. In the three push-pull treatments (but not the bait only or control treatments), 28 of 30 replicates had significantly more mass-attacked trees in the pheromone-baited outer 3 ha than in the inner ha treated with verbenone plus NHVs. The percentage of available trees ≥ 17.5 cm diameter at breast height (dbh) that were mass-attacked was < 10% in 5, 4 and 3 of 10 replicates when verbenone plus NHVs were deployed at 10-, 15-and 20-m centres, respectively, and was < 10% in two each of the bait only and control replicates. The mean ratios of newly-attacked green trees in 2003 to red trees killed in 2002 were significantly lower in the inner ha of the 10-m and 15-m centre treatments (2.6 and 2.7, respectively) than 5.9 in the untreated control. Also the pooled percentages of attacked trees that were not mass-attacked were significantly higher in the inner ha of the treatments with centres at 15 m (24.7%) and 10 m (17.6%) than in the other three treatments (all between 12% and 13%). Despite the apparent efficacy in 10-m and 15-m centre treatments, some replicates failed spectacularly. Failure was not significantly related to the incidence of red trees, but was negatively related to density/ha of available trees and positively related to mean dbh. We recommend operational implementation of the push-pull tactic at 10-m or 15-m centres when the density of available lodgepole pines is > 400/ha, the mean dbh is ≤ 25 cm, current attack is ≤ 15%, and the tactic is part of an integrated pest management program that includes sanitation harvesting. Using verbenone alone at 15-m centres would cost $380/ha (CAD), excluding labour.Key words: mountain pine beetle, Dendroctonus ponderosae, lodgepole pine, Pi...

Commercial greenhouses require high densities of managed bumble bee (Bombus occidentalis Greene, 1858 and Bombus impatiens Cresson, 1863) colonies to pollinate crops such as tomatoes (Lycopersicon esculentum Miller). We examined drifting, a behavioural consequence of introducing closely aggregated colonies into greenhouse habitats, to determine possible explanations for observed drifting frequencies. Bee drift is normally associated with increased individual mortality and disease transfer between colonies. In this study, individual bees frequently drifted into and remained within foreign colonies. More drifting bees were found in colonies with higher worker and brood populations and greater pollen stores. Increased intracolony aggressive interactions were not associated with a higher number of drifting bees. Drifting bees had a significantly greater number of mature eggs in their ovaries than did resident worker bees residing in colonies hosting drifters, suggesting that drifting could potentially increase the fitness of individual worker bees and may not be solely a function of disorientation and (or) nectar robbing. Taken together, our results suggest that drifting of workers into foreign colonies within greenhouses may demonstrate a predisposition to social parasitism. This selfish worker reproduction challenges our previous understanding of social insect societies as being cooperative societies.

Studies of Varroa destructor orientation to honey bees were undertaken to isolate discrete chemical compounds that elicit host-finding activity. Petri dish bioassays were used to study cues that evoked invasion behaviour into simulated brood cells and a Y-tube olfactometer was used to evaluate varroa orientation to olfactory volatiles. In Petri dish bioassays, mites were highly attracted to live L5 worker larvae and to live and freshly freeze-killed nurse bees. Olfactometer bioassays indicated olfactory orientation to the same type of hosts, however mites were not attracted to the odour produced by live pollen foragers. The odour of forager hexane extracts also interfered with the ability of mites to localize and infest a restrained nurse bee host. Varroa mites oriented to the odour produced by newly emerged bees (<16 h old) when choosing against a clean airstream, however in choices between the odours of newly emerged workers and nurses, mites readily oriented to nurses when newly emerged workers were <3 h old. The odour produced by newly emerged workers 18-20 h of age was equally as attractive to mites as that of nurse bees, suggesting a changing profile of volatiles is produced as newly emerged workers age. Through fractionation and isolation of active components of nurse bee-derived solvent washes, two honey bee Nasonov pheromone components, geraniol and nerolic acid, were shown to confuse mite orientation. We suggest that V. destructor may detect relative concentrations of these compounds in order to discriminate between adult bee hosts, and preferentially parasitize nurse bees over older workers in honey bee colonies. The volatile profile of newly emerged worker bees also may serve as an initial stimulus for mites to disperse before being guided by allomonal cues produced by older workers to locate nurses. Fatty acid esters, previously identified as putative kairomones for varroa, proved to be inactive in both types of bioassays.

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