Congeneric mutualist ant symbionts (Tetraponera, Pseudomyrmecinae) differ in level of protection of their myrmecophyte hosts (Barteria, Passifloraceae)

Abstract

Barteria fistulosa and B. dewevrei, central African rain-forest trees, provide nesting cavities for Tetraponera aethiops and T. latifrons ants, respectively, which protect them against herbivores. To compare protection efficiency between these two symbioses, for 20 plants of each species in two sites in Gabon we measured the time elapsed before ants reached a focal leaf, for host leaves that were undisturbed, damaged (cut with scissors) or subjected to slight vibration (mimicking such damage), and for damaged leaves of the non-host Barteria species. Tetraponera aethiops displayed stronger protective behaviour than did T. latifrons. Time to reach a damaged host leaf (4.5 ± 2.6 min, mean ± SD) did not differ significantly from time to reach a leaf subjected to slight vibration (5.2 ± 3.0 min) for T. aethiops, but response to a leaf subjected to slight vibration (9.5 ± 1.9 min) was significantly slower than that to a damaged leaf (7.8 ± 1.9 min) for T. latifrons. The faster response of T. aethiops to slight vibration may have masked a response of this species to chemical signalling. Both ants reached damaged host leaves faster than damaged leaves of the non-host Barteria sp., indicating host plant specificity in ant responses.

Association patterns of swollen‐thorn acacias with three ant species and other organisms in a dry forest of Panama

“…For instance, defending and non‐defending acacia ants in Mexico are distributed among high‐ and low‐reward swollen‐thorn acacia species (Heil et al., 2009). Similarly, two Tetraponera species (Pseudomyrmicinae) mutualistic with two Barteria (Passifloraceae) species have been reported to vary in the sensitivity and response to leaf damage cues (Kokolo et al., 2019). However, those two examples document differences in ant behavior defending different plant species, which is not the case in our study.…”

The ant genus Tetraponera (Hymenoptera: Formicidae) in the Afrotropical region: taxonomic review and key to species

“…At a study site in Sapoba Forest, Nigeria, Janzen (1972) reported that both species had similar biology, but that the colonies occurred in a ratio of about 1:100. More recent work in Gabon has shown that the two species have differing hostplant preferences and protective behavior, with T. latifrons occurring more frequently in Barteria dewevrei, and T. aethiops being preferentially associated with Barteria fistulosa and showing a stronger reaction to leaf disturbance (Kokolo et al 2019). Given differences in morphology of the workers and larvae (Wheeler 1918;Wheeler & Wheeler 1956) it seems probable that there are additional biological differences between the two species yet to be discovered.…”

“…); Kwale: diani Beach [as "diana Beach"] (Krauss, N. l. h.); Mozambique: Cabo Delgado: 24.5 km 346° from Pemba, 20 m (Fisher, B. l.; et al) In the original description the type locality is stated to be "S. Africa" (Smith 1858) but this is almost certainly an error. Tetraponera aethiops occurs in wet tropical forest from Nigeria to dr Congo and western Uganda, and is an obligate inhabitant of two myrmecophytic species of Barteria (Passifloraceae) (Bequaert 1922; Kokolo et al 2019) that do not occur in South Africa. T. aethiops has also been recorded (Stitz 1910) nesting in live stems of Heinsia myrmoecia (rubiaceae), but davidson & McKey (1993) cast doubt on this report, noting that the internodal swellings of that plant are too small to support a large ant species such as T. aethiops.…”