The alarm behaviour of grass-cutting ants and the pheromone enhancement of bait for their control
The alarm behaviour of grass-cutting ants and the pheromone enhancement of bait for their control
Grass-cutting ants (Hymenoptera: Formicidae: Attini) are important economic pests of pastures in the neotropics, and current citrus pulp-based baits are inefficient at controlling them. The potential for using alarm pheromones to enhance the attractiveness of the baits was investigated for two grass-cutting species, Atta bisphaerica and Atta capiguara. The compositions of the alarm pheromones of these species were examined with gas chromatography and mass spectrometry, and case and colony variations quantified. The pheromones of A. bisphaerica and A. capiguara were remarkably similar, and were composed of a complex mix of volatiles in which 4-methyl-3-heptanone and 2-heptanone were the most abundant compounds. Small but consistent differences were found between the worker castes and between individual colonies. Bioassays in the field established that 4-methyl-3-heptanone attracted large numbers of ants and was the best candidate compound for the enhancement of bait. It greatly increased the attractiveness of citrus pulp bait to A. bisphaerica and A. capiguara, either when applied in a sealed plastic sachet or as a loose pile. Minor workers were found to be the main caste that responded during the alarm reaction, and appeared to patrol the trail area for threats. The largest response was achieved when alarm sources were placed close to the trail entrance hole, where minor workers were proportionally most abundant. However, minor workers could not cut sachets or transport bait, and alarmed ants are also less likely to transport bait. Furthermore, grass-cutting ants were much less likely to transport bait than A. laevigata, a species that is known to readily harvest citrus pulp baits. In spite of these drawbacks, harvest of the bait by both A. bisphaerica and A. capiguara was enhanced slightly by the presence of 4-methyl-3-heptanone when it was applied in a sealed plastic sachet, and significantly enhanced when the bait was applied as a loose pile.
University of Southampton
Hughes, William Owen Hamar
1999
Hughes, William Owen Hamar
Hughes, William Owen Hamar
(1999)
The alarm behaviour of grass-cutting ants and the pheromone enhancement of bait for their control.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Grass-cutting ants (Hymenoptera: Formicidae: Attini) are important economic pests of pastures in the neotropics, and current citrus pulp-based baits are inefficient at controlling them. The potential for using alarm pheromones to enhance the attractiveness of the baits was investigated for two grass-cutting species, Atta bisphaerica and Atta capiguara. The compositions of the alarm pheromones of these species were examined with gas chromatography and mass spectrometry, and case and colony variations quantified. The pheromones of A. bisphaerica and A. capiguara were remarkably similar, and were composed of a complex mix of volatiles in which 4-methyl-3-heptanone and 2-heptanone were the most abundant compounds. Small but consistent differences were found between the worker castes and between individual colonies. Bioassays in the field established that 4-methyl-3-heptanone attracted large numbers of ants and was the best candidate compound for the enhancement of bait. It greatly increased the attractiveness of citrus pulp bait to A. bisphaerica and A. capiguara, either when applied in a sealed plastic sachet or as a loose pile. Minor workers were found to be the main caste that responded during the alarm reaction, and appeared to patrol the trail area for threats. The largest response was achieved when alarm sources were placed close to the trail entrance hole, where minor workers were proportionally most abundant. However, minor workers could not cut sachets or transport bait, and alarmed ants are also less likely to transport bait. Furthermore, grass-cutting ants were much less likely to transport bait than A. laevigata, a species that is known to readily harvest citrus pulp baits. In spite of these drawbacks, harvest of the bait by both A. bisphaerica and A. capiguara was enhanced slightly by the presence of 4-methyl-3-heptanone when it was applied in a sealed plastic sachet, and significantly enhanced when the bait was applied as a loose pile.
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Published date: 1999
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Local EPrints ID: 464012
URI: http://eprints.soton.ac.uk/id/eprint/464012
PURE UUID: 3f5948a3-f42a-456a-a43d-2d18f481a8cf
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Date deposited: 04 Jul 2022 21:00
Last modified: 04 Jul 2022 21:00
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Author:
William Owen Hamar Hughes
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