A facultative mutualism between aphids and an invasive ant increases plant reproduction

Abstract

Abstract. 1. The consequences to plants of ant-aphid mutualisms, particularly those involving invasive ants, are poorly studied. Ant-aphid mutualisms may increase or decrease plant fitness depending on the relative cost of herbivory by ant-tended aphids versus the relative benefit of increased ant suppression of other (non-aphid) herbivores.2. We conducted field and greenhouse experiments in which we manipulated the presence and absence of cotton aphids (Aphis gossypii ) on cotton plants to test the hypothesis that a mutualism between cotton aphids and an invasive ant, the red imported fire ant (Solenopsis invicta), benefits cotton plants by increasing fire ant suppression of caterpillars. We also manipulated caterpillar abundance to test whether the benefit of the mutualism varied with caterpillar density.3. We found that more fire ants foraged on plants with cotton aphids than on plants without cotton aphids, which resulted in a significant reduction in caterpillar survival and caterpillar herbivory of leaves, flower buds, and bolls on plants with aphids. Consequently, cotton aphids indirectly increased cotton reproduction: plants with cotton aphids produced 16% more bolls, 25% more seeds, and 10% greater seedcotton mass than plants without aphids. The indirect benefit of cotton aphids, however, varied with caterpillar density: the number of bolls per plant at harvest was 32% greater on plants with aphids than on plants without aphids at high caterpillar density, versus just 3% greater at low caterpillar density.4. Our results highlight the potential benefit to plants that host ant-hemipteran mutualisms and provide the first experimental evidence that the consequences to plants of an ant-aphid mutualism vary at different densities of non-aphid herbivores.

Disruption of ant-seed dispersal mutualisms by the invasive Asian needle ant (Pachycondyla chinensis)

“…For example, it may have arisen because of differences in rates of herbivory in intact and invaded plots, if P. chinensis does not prey on the herbivores of H. arifolia to the same extent as native ant species do (Holway et al 2002;Styrsky and Eubanks 2010). However, the percentage of H. arifolia with apparent damage by herbivores did not differ between invaded (12% ± 3.60) and intact plots (7% ± 2.60) (t = 1.08, n = 23, P = 0.29).…”

Can the absence of ants interfere in the arthropods abundance on corn plants (Zea mays L. - Poaceae)?

“…According to the results of this Other study showed that Dermaptera of genus Dorus are efficient herbivorous predators in corn monoculture (see Cruz 1991). Additionally, Buschman et al (1977) Some studies have shown that the result of ant-plant interaction is dependent of the species of predatory ants involved interaction (Byk & Del-Claro, 2010;Calabuig et al, 2015) and of the strategies of herbivorous against predation (Bächtold & Alves-Silva, 2013;Carita et al, 2006;Styrsky & Eubanks, 2010). Nevertheless, little is known about the behavior between pairs (predator-prey) determining plant protection.…”

Effect of ant attendance on aphid population growth and above ground biomass of the aphid's host plant

“…In the present study, the ant T. erraticum not only improved the performance of A. gossypii colonies in terms of the population growth rates of all the different sized aphid colonies (El-Ziady & Kennedy, 1956;Flatt & Weisser, 2000;Powel & Silverman, 2010;Styrsky & Eubanks, 2010), but also benefi ted the aphid's host plant (Hansen et al, 2006). The positive consequences of the ant-aphid system for the host plant, in the absence of aphid natural enemies and alternative herbivores, probably indicates that ants (as the active partners in the mutualism) can affect the fi tness of the aphid's host plant as long as the requirements of the colony are satisfi ed.…”

“…The cost to benefi t ratio in mutualism changes with the intrinsic features of both partners (e.g. the initial number of partners at the commencement of a relationship) and biotic/abiotic environmental factors (Stadler & Dixon, 1998;Styrsky & Eubanks, 2010;Yoo & Holway, 2011;Barton & Ives, 2014;Singh et al, 2016). Thus, mutualism has a context-dependent aspect, that is, the net benefi ts for a given species depend on ecological conditions (Zhang et al, 2015).…”