Figure 1. Behavioral responses of A. cerana (Ac) to A. dorsata (Ad) and A. mellifera (Am) sting alarm pheromones.

(A) Images showing Ac and Ad sharing a C. haematocephala inflorescence at the field site, and being attacked by weaver ants (Oecophylla smaragdina) while foraging on these plants. The ants are outlined on the third image because they are similar in color to the inflorescence. (B) Chromatogram confirming Ac sting alarm pheromone components. Results of bioassays testing Ac forager avoidance of (C) sting alarm pheromone from different species of bees at different levels (1 or 15 bee equivalents = 1 or 15X) or (D) major sting pheromone components. To control for the possibility that bees did not avoid 1 Ad bee equivalent of MB or IP, we also tested their responses to higher levels of these compounds, which elicited clear antennal responses. The tested amount of each compound is shown below the bioassay results: black bars = 1 Ad equivalent and blue bars = higher levels. Compounds are arranged by decreasing volatility (lower vapor pressure = lower volatility). The dashed line gives the null expectation of no feeder preference. Asterisks denote treatments that elicited significant avoidance (P < 0.05, see Table 1). The mean ± 1 standard error is shown.