Ecology and evolution of cycad‐feeding Lepidoptera

Abstract

Cycads are an ancient group of tropical gymnosperms that are toxic to most animals – including humans – though the larvae of many moths and butterflies (order: Lepidoptera) feed on cycads with apparent immunity. These insects belong to distinct lineages with varying degrees of specialisation and diverse feeding ecologies, presenting numerous opportunities for comparative studies of chemically mediated eco‐evolutionary dynamics. This review presents the first evolutionary evaluation of cycad‐feeding among Lepidoptera along with a comprehensive review of their ecology. Our analysis suggests that multiple lineages have independently colonised cycads from angiosperm hosts, yet only a few clades appear to have radiated following their transitions to cycads. Defensive traits are likely important for diversification, as many cycad specialists are warningly coloured and sequester cycad toxins. The butterfly family Lycaenidae appears to be particularly predisposed to cycad‐feeding and several cycadivorous lycaenids are warningly coloured and chemically defended. Cycad–herbivore interactions provide a promising but underutilised study system for investigating plant–insect coevolution, convergent and divergent adaptations, and the multi‐trophic significance of defensive traits; therefore the review ends by suggesting specific research gaps that would be fruitfully addressed in Lepidoptera and other cycad‐feeding insects.

A switch to feeding on cycads generates parallel accelerated evolution of toxin tolerance in two clades ofEumaeuscaterpillars (Lepidoptera: Lycaenidae)

“…Rather, in accord with ref. 23, it is nested deep within the tree, forming a monophyletic group with Theorema and Mithras. The length of the branch leading to Eumaeus is much longer than that of its sister (Fig.…”

Evolutionary trade-offs between male secondary sexual traits revealed by a phylogeny of the hyperdiverse tribe Eumaeini (Lepidoptera: Lycaenidae)

“…The tribe encompasses a staggering array of ecological and behavioural diversity, thriving in habitats from the Alaskan subarctic to temperate Chile, from sea level to the high Andes, and in environments as distinct as the Amazon rainforest and the Atacama Desert [5][6][7]. Species of Eumaeini possess a broad spectrum of adaptations to avoid predation, including complex larval interactions with ants, eyespots and tails that resemble a 'false head' at their posterior end, and aposematic coloration advertising toxins sequestered from their host plants [8][9][10][11][12].…”

Cycad-Weevil Pollination Symbiosis Is Characterized by Rapidly Evolving and Highly Specific Plant-Insect Chemical Communication

“…Methyl salicylate is involved in reproduction for Zamia integrifolia yet likely also has other ecological functions as it is known to play a great many roles in insect behavior from attraction (James, 2003) to deterrence (Ninkovic et al, 2003) and even as an anti-aphrodisiac transferred in nuptial gifts (Andersson et al, 2000). Larvae of the lycaenid butterfly, Eumaeus atala (Lepidoptera) larvae in Florida and the Caribbean are major pests of Zamia (Whitaker and Salzman, 2020) and while the chemical ecology of host plant localization or response to methyl salicylate remains unknown in E. atala, it likely further impacts the evolution and diversification of both Zamia and Rhoplaotria lineages.…”