Ants climb plants because they cannot swim: ant presence on flowers during the flood season reduces the frequency of floral visitors

Abstract

1. Seasonal changes in environments may not only affect habitat connectivity but may also affect its use by species and their interactions. Thus, during the flood season, ants are forced to develop survival strategies such as vertical plant migration. 2. According to this, it has been hypothesized that the presence of ants may directly affect plant-pollinator interactions. 3. Thus, we asked the following questions: (i) Are floral visitors of Hyptis brevipes expelled due to ant presence on inflorescences during the flood period? (ii) Is the ant effect mediated by the abundance of ants foraging on inflorescences? And, (iii) Does flower abundance predict the abundance of floral visits and ants? 4. We experimentally sampled 59 H. brevipes plants with and without ants during the flooded season, and observed no differences in flower abundance between ant treatments. 5. The probability of detaining floral visitors on H. brevipes increased with ant abundance and exceeded 50% possible repellency, but the probability of visitor deterrence was not related to flower abundance. Furthermore, the abundance of flowers did not predict the number of ants on H. brevipes individuals or the frequency of floral visits. 6. Consequently, ant repelling effects are pronounced when there are more ants foraging on plants. However, the ant repelling effect can be mitigated when plants flourish all year-round and exhibit higher concentrations of flowers in the dry months. Additionally, the different sexual functions of plants may present specific responses due to the explosive pollination mechanism associated with ant effects.

Among‐species variation in flower size determines florivory in the largest tropical wetland

“…Moreover, pollinators can consume flower whorls of aquatic plants, simultaneously acting as florivores (e.g., Trigona spinipes in Nymphaea pulchella flowers; Chalegre et al, 2020). Previous studies have also shown that some ant species visit plants during the rainy season in the Pantanal, repelling nectar thieves and pollinators from flowers (e.g., Hyptis brevipes, see Souza et al, 2020). Ant-plant mutualistic interactions, in which ants act as biotic defenses against herbivores and florivores, are widespread across tropical plants (Heil and Mckey, 2003;Rosumek et al, 2009;Mesquita-Neto et al, 2020).…”

“…In addition, the climatic seasonality and subsequent flooding cycle might lead to variable flower sizes throughout the year (plants during the wet season have larger flowers than plants flowering in the dry season; C. Aoki and A. L. Teixido, personal observations). Moreover, interactions between some species and ants may increase during the flood season, which may restrict pollinator visits (Souza et al, 2020) and/or change interactions with leaf and flower herbivores mediated by biotic defenses (e.g., Rosumek et al, 2009).…”

“…Thus, more conspicuous, larger-flowered species during the rains may suffer higher rates of florivore attack. Seasonality may also limit the substrate where plants occur (e.g., aquatic and terrestrial substrate from wetlands; Pott and Pott 2000), which, ultimately, may also influence flowering (Fava and Gomes, 2017;Souza et al, 2018Souza et al, , 2020. It is reasonable, therefore, to expect a potential simultaneous influence of environmental conditions such as the hydrological processes and plant substrate, together with the seasonal variation in flower size on the attraction and occurrence of florivores.…”

Chrysophyllum marginatum (Sapotaceae): Generalist pollination and cryptic gynomonoecious

“…Ants only “patrol” on branches, and their role in interacting with C. marginatum plants needs to be investigated. The presence and abundance of ants among the flowers may influence the behavior and frequency of visits by other floral visitors, including potential pollinators (Souza, Baronio, Weirich, Oliveira, Ferreira, Arruda, & Aoki, 2020). So, although it was not demonstrated that ants were interfering in C. marginatum pollination (this study), the information recorded here is important for future research on plant–insect interactions.…”

Colônias à deriva: efeitos do alagamento no sistema mutualístico Azteca-Cecropia

“…Um mutualismo dos mais notórios da região tropical é a interação entre formigas do gênero Azteca e árvores pioneiras do gênero Cecropia (Janzen, 1973;Beattie, 1985;Davidson, 1993;Longino, 2001;Heil & Mckey, 2003). Apesar de ser um sistema ecológico amplamente conhecido, não existem estudos que testem os efeitos do alagamento sobre a interação Azteca-Cecropia (mas veja : Emer, Venticinque & Fonseca, 2013;Câmara et al, 2018;Souza et al, 2020; para efeitos sobre outras espécies de formigas). Nessa associação a planta oferece alimento e local de nidificação (Janzen, 1969;Rickson, 1976) em troca de proteção contra herbívoros, parasitas, e até mesmo fertilização, fornecidas pelas formigas (Marting, 2018a).…”