Negative effects of ant-plant interaction on pollination: costs of a mutualism

The mutualism of ants and extrafloral nectary (EFN)-bearing plants is known to reduce rates of herbivory. However, ants may have negative impacts on other mutualisms such as pollination, constituting an indirect cost of a facultative mutualism. For instance, when foraging on or close to reproductive plant parts ants might attack pollinators or inhibit their visits. We tested the hypothesis that ants on EFN-bearing plants may negatively influence pollinator behavior, ultimately reducing plant fitness (fruit set). The study was done in a reserve at Brazilian savannah using the EFN-bearing plant Banisteriopsis malifolia (Malpighiaceae). The experimental manipulation was carried out with four groups: control (free visitation of ants), without ants (ant-free branches), artificial ants (isolated branches with artificial ants on flowers) and plastic circles (isolated branches with plastic circles on flowers). We made observations on flower visitors and their interactions, and measured fruit formation as a proxy for plant fitness. Our results showed that pollinators hesitated to visit flowers with artificial ants, negatively affecting pollination, but did not hesitate to visit flowers with plastic circles, suggesting that they recognize the specific morphology of the ants. Pollinators spent more time per flower on the ant-free branches, and the fruiting rate was lower in the group with artificial ants. Our results confirm an indirect cost in this facultative mutualism, where the balance between these negative and positive effects of ants on EFN-bearing plants are not well known.

Survival analysis of an impulsive stochastic facultative mutualism system with saturation effect

A system of impulsive stochastic differential equations is proposed as a two-species facultative mutualism model subject to impulsive and two coupling noise source perturbations, in which the saturation effect is taken into account. A set of sufficient criteria for extinction (exponential extinction and extinction) and permanence (permanence in time average and stochastic permanence) of the system are established. Extensive simulation figures are demonstrated to support the theoretical findings. Meanwhile, we look at the effects of coupling white noises, impulses, intrinsic growth rates, intra-specific competition rates and inter-specific mutualism rates on the survival of populations.

Occurrence of Aetalion reticulatum (Linnaeus) (Hemiptera: Aethalionidae) on Dipteryx alata Vogel (Fabaceae) in Minas Gerais, Brazil

The baruzeiro or baru (Dipteryx alata Vogel) is a tree species native to Brazil that is known for its production of edible nuts with high nutritional value. However, little is known about the insects associated with this forest species. Therefore, this study aims to document the occurrence of leafhoppers on baruzeiro trees in the state of Minas Gerais, southeastern Brazil. We therefore examined baruzeiro plants in an afforestation plot at the Universidade Federal de Uberlândia (18°43'33"S; 47°31'31"W) in August 2020, located in the municipality of Monte Carmelo, Minas Gerais. The leafhopper species was identified as Aetalion reticulatum (Linnaeus) (Hemiptera: Aethalionidae). The ant species Camponotus crassus Mayr (Hymenoptera: Formicidae) was found to feed on the honeydew released by leafhoppers, demonstrating facultative mutualism between the species. This is the first report of A. reticulatum on D. alata in Minas Gerais.

The enemy of my enemy is my friend: Nematode infection of pollinating and non-pollinating fig wasps has net benefits for the fig-fig wasp pollination mutualism

Mutualistic associations between species pairs are ubiquitous in nature but are also components of broader organismal community networks. These community-level associations have shaped the evolution of individual mutualisms through interspecific interactions ranging from secondarily mutualistic to intensely antagonistic. Our understanding of this complex context remains limited because identifying species interacting with focal mutualists and assessing their associated fitness benefits and costs is difficult, especially over space and through time. Here, we focus on a community comprised of a fig and fig wasp mutualist, eight non-pollinating fig wasp (NPFW) commensals/antagonists, and a nematode previously believed to be associated only with the pollinator wasp mutualist. Through repeated sampling and field experiments, we identified that all NPFWs are targets for infection by this nematode. Further, this infection can impact NPFWs more severely than either mutualistic partner, suggesting a novel role of density-dependent facultative mutualism between fig and wasp mutualists and the nematode.

Dynamics of Almost Periodic Solution for a Delayed Facultative Mutualism Model Involving Negative Feedback Terms

By using some new analytical techniques, modified inequalities and Mawhin’s continuation theorem of coincidence degree theory, some sufficient conditions are obtained for the boundedness of the solution and the existence of at least one positive almost periodic solution of a kind of two-species model of facultative mutualism with time delays. Further, the global asymptotic stability of the positive almost periodic solution of this model is also considered. Some examples and numerical simulations are also given to illustrate the main results of this paper.