Interactions between ants and aphidophagous and coccidophagous ladybirds

Abstract

Aphidophagous and coccidophagous coccinellids come into conflict with homopteran‐tending ants for access to food. Antagonistic interactions between coccinellids and ants may be competitive or non‐competitive. Competitive interactions occur when coccinellids attack aphids or coccids that are being tended by ants for honeydew. Non‐competitive interactions include all interactions away from ant‐tended homopteran colonies. We here review observations and studies of such interactions. We note that most competitive interactions occur at times when untended aphids/coccids are scarce. We describe the chemical and physical defences that coccinellids use against ant aggression and consider whether these have evolved as general anti‐predator deterrents or specifically in response to ants. Myrmecophilous coccinellids are then considered, with particular focus on the two most studied species, Coccinella magnifica and Platynaspis luteorubra. We note that the myrmecophily of the two species has the same adaptive rationale—to enable the ladybirds to prey on ant‐tended aphids at times of aphid scarcity—but that it is based on different traits to facilitate life with ants. Finally, we consider the role of ants in the evolution of habitat specialisation in some coccinellids.

Evolutionary Perspectives on Myrmecophily in Ladybirds

“…The Coccinellidae family consists of seven subfamilies [25] among which five include myrmecophilous species: Scymninae, Ortaliinae, Chilocorinae, Coccinellinae, and Coccidulinae [26][27][28][29][30][31] (Table 1). Interestingly, only one myrmecophilous species has been recorded to date in each of the three subfamilies Ortaliinae, Chilocorinae, and Coccinellinae and two in the subfamily Coccidulinae whereas there are eight species from the Scymninae subfamily belonging to four different tribes: one species from the Diomini tribe, two species from the Hyperaspidini and Brachiacanthadini tribes, and three species from the Scymnini tribe.…”

Laboratory studies on intraguild predation and cannibalism among coccinellid larvae (Coleoptera: Coccinellidae)

“…The presence of the waxy filaments is an adaptation against attack by ants because (a) ants find it difficult to bite the larvae through the waxy covering and (b) some waxes are sticky, which may cause ants to cease attacking in order to clean their mouthparts (Majerus et al, 2007). In our laboratory experiments we often noted that both of the above delayed the occurrence of the predatory event.…”

“…The larvae of these species are able to feed on ant-attended aphid colonies (Majerus et al, 2007) or those in rolled up leaves that are not accessible to coccinellid species whose larvae are bigger (Ricci & Rondoni, pers. observ.).…”

“…Scymnus larvae are covered by a thick waxy layer that enables them to feed on aphids that are attended by ants (Volkl & Vohland, 1996;Majerus et al, 2007). The presence of the waxy filaments is an adaptation against attack by ants because (a) ants find it difficult to bite the larvae through the waxy covering and (b) some waxes are sticky, which may cause ants to cease attacking in order to clean their mouthparts (Majerus et al, 2007).…”

Whiteflies Provide Honeydew to Camponotus ants Without Receiving Reciprocal Favor

“…Nevertheless, this has yet to be empirically demonstrated. In any case, coccinellids are known to defend themselves from hemipteran-tending ants by using behavioral, physical and chemical mechanisms (Pasteels et al, 1973;Richards, 1985;Majerus et al, 2007). Because we tested only coccinellids, it is unknown whether or not these Camponotus ants could respond in the same way to other predator species.…”