The role of tending ants in host plant selection and egg parasitism of two facultative myrmecophilous butterflies

Abstract

Ovipositing adult females of myrmecophilous lycaenids are expected to select plants based on ant presence in order to maximize the survivorship of immature stages. Usually, larvae feed ants with honey-like solutions and, in turn, ants ward off parasitoids. Nonetheless, a rarely investigated approach is whether ant partners can also extend their protective behavior towards lycaenids eggs. Here, we investigated the ant-related oviposition pattern of Allosmaitia strophius and Rekoa marius; then, we compared egg parasitism according to the presence of ants. Lycaenid oviposition and egg parasitism (in percent) were experimentally compared in ant-present and ant-excluded treatments. The study plant, Heteropterys byrsonimifolia, is an extrafloral nectaried shrub which supports several ant species. We sampled 280 eggs, of which 39.65 % belonged to A. strophius and 60.35 % to R. marius. Both lycaenids eggs were significantly more abundant on branches with ants, especially those with Camponotus crassus and Camponotus blandus, two ant species known to attend to lycaenids. A. strophius and R. marius parasitism was 4.5- and 2.4-fold higher, respectively, in ant-present treatments, but the results were not statistically significant. Our study shows that ant-mediated host plant selection in lycaenids might be much more widespread than previously thought, and not restricted to obligate myrmecophilous species. Tending ants may be inefficient bodyguards of lycaenid eggs, because unlike larvae which release sugared liquids, eggs do not offer obvious rewards to ants. Ants can ward off parasitoids of larvae, as observed elsewhere, but our findings show that positive ant-lycaenid interactions are conditional and depend on immature ontogeny.

Chemical convergence between a guild of facultative myrmecophilous caterpillars and host plants

“…This occurs either because they are in the second instar when their DNOs, which produce nutritious secretions for ants, are not functional (see Fiedler, 1991;Kaminski et al, 2010a) or when they are in the pupal stage when DNOs are not retained (Mizuno et al, 2018). Indeed, some of the highest similarity values between caterpillars and host plants found in the present study were for A. strophius, a commensal myrmecophilous that does not produce nectar rewards (Kaminski & Freitas, 2010;Bächtold et al, 2014). The cuticular compounds of the facultative myrmecophilous lycaenid pupa Lycaeides argyrognomon (Berstrasser) contains not only CHCs but also several long-chain aliphatic aldehydes that suppress ant aggression even after certain antorgans are non-functional (Mizuno et al, 2018).…”

“…1): (1) Allosmaitia strophius (Godart) is an oligophagous caterpillar specialized on inflorescences of Malpighiaceae (Kaminski & Freitas, 2010). Although females prefer to oviposit on plants with ants (Bächtold et al, 2014), the caterpillars have a non-functional dorsal nectary organ (DNO)that is, they do not establish a typical food-for defense mutualistic interaction with ants, and thus are considered commensal myrmecophilous (i.e. an organism that indirectly interacts with ants) (Kaminski & Freitas, 2010;Silva et al, 2014).…”

Florivorous myrmecophilous caterpillars exploit an ant–plant mutualism and distract ants from extrafloral nectaries

“…Ideally, a (factorial) set of experiments using ants and caterpillars (DeVries ) might answer several questions not only concerning the role of each partner in plant performance but also the influence of ants on the survival of butterfly immatures (DeVries ; Bächtold et al . ). However, so far, this is not possible because riodinids are very infrequent and have always occurred in low abundance, in comparison to myrmecophilous lycaenids, since studies on ant–plant–caterpillar interactions commenced (personal observations since 2010).…”

“…; Bächtold et al . ) and little is known about ant associations within myrmecophilous riodinid caterpillars, despite recent efforts in the neotropics (Kaminski et al . ).…”

Wasps are better plant-guards than ants in the extrafloral nectaried shrub Ouratea spectabilis (Ochnaceae)

“…As well as ants, wasps are also important natural enemies of herbivores (Pereira & Trigo, 2013;Bächtold et al, 2014), especially endophytic weevils (Torezan-Silingardi, 2011). For instance, the social Polistinae wasp Brachygastra lecheguana Latr.…”