The compound is placed on a stationary lure (e. g. a small cork, cotton ball or piece of ﬁlter paper) on the alighting board at the entrance to a hive and the number of bees alerted by it and the behaviour of bees toward it compared with the effect of an untreated control (e. g. Boch et al., 1962, 1970; Boch and Shearer, 1965b; Free et al., 1987c).
Several components (isopentyl acetate, n-butyl acetate, hexyl acetate, 2-nonyl acetate, eicosanol acetate, octanoic acid, 1-butanol, 1-pentanol, 2-heptanol, l—octano1) alert the colony and attract alerted bees, while others (e.g. octyl acetate, p-cresol and benzol alcohol) fail to alert the colony and repel bees.
The reaction of bees to the top pheromone components sometimes increases with concentration and may sometimes actually differ with increasing concentration. For example, when isopentyl acetate is presented at the hive entrance (Boch and Shearer, 1971) there is, at ﬁrst, with increase in concentration a marked increase in the number of responding bees. But, at excessive concentration the bees hesitate in their approach to the odour source, they stop at some distance from it, and make short probing movements forward and backward, turn away and run about in an erratic manner. 1-Pentanol which is attractive at low concentrations also becomes repellent at high concentrations (Free et al. , l987e). Learn more Max Attraction Gold at http://youthbruce.com/2016/05/03/does-max-attraction-gold-work/
Alerting in cages bioassay
Small groups (10-50) of queenless bees in cages are exposed to the compound and the number that respond by increased locomotion and partial extension of the wings, and the intensity of the response, is recorded. Check out the top pheromones at http://pheromones-planet.com.
The acetate, benzyl acetate and 2-nonanol) induce the bees to expose their Nasonov glands and fan their wings (Collins, 1980, 1981; Collins and Blum, 1982). The signiﬁcance of this behaviour is obscure but such queenless, homeless bees readily engage in scenting behaviour in response to disturb- ance. Chemical compounds, not known in honeybee pheromones, may give a similar response (Collins and Blum, 1983), suggesting that it is related to the presence of a strange odour rather than being a speciﬁc response to a pheromone component.
In more natural circumstances alarm‘ pheromone has the opposite effect. When bees of a swarm settle around their queen they expose their Nasonov glands and fan their wings. Releasing isopentyl acetate near the queen inhibits scenting behaviour and no additional workers join her (Morse, 1972). When a swarm is given a strange queen a few of the workers soon clasp her with their mandibles, protrude their stings and probably release alarm pheromone; release of Nasonov pheromone and attraction of additional workers ceases (Boch and Morse, 1974).
Tests of several alarm pheromone components on bees that are fanning and scenting at their hive entrance, as they move into the hive to join the cluster, showed that some inhibited scenting (1-pentanol, (Z)-ll-eicosen-l-ol) some inhibited clustering (phenol, p-cresol) some inhibited both (isopentyl acetate, n-octyl acetate, 2-nonyl acetate, octanoic acid, 1-butanol, 1-octanol), and others had no effect (Free et al., 1983b, 1987e).
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