On the evolution of diversity of sexual and protective characters in neotro- F I pical Ctenuchinae (: Arctiidae) [email protected] SLIII Michael Boppré 1, Christoph L. Häuser 2 & Boris Kreusel 2 1 Forstzoologisches Institut, Albert-Ludwigs-Universität, D-79085 Freiburg i.Br., Germany Tc 2 Staatliches Museum für Naturkunde, D-70191 Stuttgart, Germany ScIII Co Key words: biodiversity – – pharma­ Pharmacophagous relations to plants cophagy – defensive devices – aposematism containing pyrrolizidine alkaloids (PAs) – rings – acoustic communication Many Ctenuchinae are pharmacophagous with Co conjunctiva Ep epaulette alar – male courtship pheromones – secondary respect to PAs, i.e., they gather these secon- ScIII metascutum SLIII metascutellum plant substances – unpalatability – sexual dary plant chemicals independent of nutritional Tc counter tympanum Tympanal organ of the Syntomis type TCav tympanal cavity behaviour requirements to increase their fitness. This TcCav counter tympanal cavity abdominal Th tympanal hood thoracal The Ctenuchinae (= Syntominae) are a syndrome is found in several other Lepidop­ Tm tympanum subfamily of the Arctiidae (tiger moths) which teran taxa (Danainae, Ithomiinae, , comprises mostly small to medium sized, often Agaristinae) but also in the Coleoptera (Altic­ conspicuously colored moths. It contains word­ inae: Gabonia), Orthoptera (Pyrgomorphidae: SLIII wide ca 2,000 species distributed throughout Zonocerus) and Diptera (Chloropidae). TcCav tropical and subtropical areas, with the great majority of species occurring in the neotropical Horama oedippus displaying its aposematic characters. Natural sources of PAs are certain Boragi­ Tc ventral valve region from where currently about 1,800 spe- naceae (e.g., Heliotropium), Asteraceae and ScIII In a long-term research project we aim to under­ Th cies are described. Fabaceae. Adult moths gather PAs exclusively Tm femural stand the many ecological adaptations and their Ep The group is exceptionally diverse with from withered or dry parts of PA-plants. With TCav TCav linkages as well as the evolutionary significance Co respect to morphological characters (tymbal, their proboscides they apply a fluid onto the of the diversity of protective mechanisms and tympanal and androconial organs), behavioural dry plant material to extract PAs for uptake as androconial systems realized in this fascinating (PA-pharmacophaguous, protective) and ecolo­ solution. The same behaviour can be elicited group of Lepidoptera by undertaking morpholo­ gical (cryptic, aposematic, mimicry) features. by pure PAs, showing that the target com- Tympanal organ of the Dinia type gical, ecological and systematic studies but In South America, ctenuchines occur in also ethological and chemical investigations. all biogeographic zones throughout in con­ Here, we present an overview on some aspects A siderable abundance, several taxa being wide­ SEM of a tymbal organ of our study. spread and others having a limited distribution range. There are day-flying as well as nocturnal Mimetic and defensive characters pounds also represent the source of the luring Androconial organs species which can be quite simply surveyed in Tymbal and tympanal organs Many ctenuchine species are exceptionally stimulatory cues and that there are no other Sexual communication involves male courtship the field (by netting / at light traps / at selective Production of ultrasonic clicks by tymbal organs colourful exhibiting aposematic patterns (see chemicals involved in eliciting this response; pheromones emitted from androconial organs (PA-)baits). Thus, Ctenuchinae can be consi­ located at the metathorax is common in Cte­ figs). eS veral genera (Sphecosoma, Macrocne­ long‑range attraction is mediated by volatile which occur in a striking structural diversity in dered to represent a key group for assessing nuchinae. There are well or poorly sclerotized me, Isanthrene, Pseudosphex) perfectly re­ breakdown products of the non‑volatile PAs. Ctenuchinae. Large protrudable and expand­ biodiversity in the neotropics. types with or without microtymbals in different semble wasps or other aculeate Pure PAs are equally attractive, i.e. baits made numbers. able abdominal scent organs are found as and provide classical text book examples for of PAs can be used for selective baiting. well as brush-like structures on the wings, the Batesian mimicry („wasp moths“). However, Of some ctenuchine taxa only males visit dry At least, six types of tympanal organs can legs, at the thorax and in a ventral abdominal most Ctenuchinae are quite well self-defended PA-plants, of others both sexes or females only be recognized differing with respect to pre­ pouch. The androconial hairs exhibit diagnostic by distastefulness through sequestered secon­ O characters, too. B C exhibit pharmacophagy. sence or absence of tympanum, counter tympa­ dary plant compounds, the production of ultra­ num, attachment of scoloparium, expression of Desmotricha ursula Eucereon marmoratum sonic clics, frothing and extrusion of defensive N PAs are generally repellent to non‑adapted prespiracular hood, and tympanal cavity. processes – many are thus rather Mullerian and serve as protective devices for danaidone Functionally, the clicks are employed in se- than Batesian mimics. Mimetic associations the plants that produce them. By sequestration xual communication but also to gain protection also involve beetles (e.g., Lycidae), but fau­ and storage of PAs many, if not all, PA-phar­ OH from bats; they interfere with bats‘ ecolocation nistic studies on mimicry rings are missing. S macophagous taxa gain protection from pre­ system and/or are acoustic aposematic charac­ O 2´ 3´ Horama plumipes Heliura balia OH H S dators, and this is reflected by the aposematic ters. Systematics 7 R O coloration and lifestyle of many of the species OR The Ctenuchinae (Ditrysia; Macrolepidoptera; D in question. In addition, males of several lepido­ Behaviour ; Arctiidae) are currently divided N pterans – including Ctenuchidae – use PAs as Protective behaviour not only involves apose­ into three tribes: Amatini, Ctnenuchini, and precursors for the biosynthesis of sex phero­ matic colours, sounds and lifestyle but also SEM of scent brush SEMs of androconial hairs Euchromiini of which only the latter two are mone components required for the acceptance characteristic patters of escape behaviours. Episcepis lenaeus Aclytia heber represented in the New World. of a courting male by a female. Such sexual Sexual behaviour is quite poorly understood The last monographic treatments are by E communication can also relate to chemical in Ctenuchinae and only a few species have Draudt (1916-1919) and Hampson (1914, defence: with his spermatophore a male can been studied with respect to mate-finding and 1920) and most taxa are in need of a thorough transfer large amounts of PAs as a nuptial gift mate choice although androconial organs sug- revision; for several genera it is yet unresolved to the female, which then gains protection for gest complex courtship behaviours. Mydromera isthmia Correbidia terminalis if they belong to Ctenuchinae or Arctiinae. Part herself and also protects her offspring by incor­ Because PA-pharmacophagy is not related of our project is the compiliation of a compre- porating PAs into the eggs. to primary metabolic processes and ordinary hensive, illustrated catalogue of all nominal host plants, qualitative as well as quantitative taxa in the Ctenuchinae based on examination Characters: PA-gathering diurnal or nocturnal, manipulations of defensive potency and/or and verification of original ed scriptions and type male or female biased / storage of converted or pheromonal outfit are possible without any ra ti­ SEMs of androconial hairs Pseudospex sp. Loxophlebia austera spe­cmens. unconverted PAs / use of PAs for male phero­ ficial disturbance of the – this enables P r o s p e c t s mone biosynthesis / ... experimental approaches to the role(s) of By recording, evaluating and interlinking data Chemical ecology pheromones but also to (Mullerian / Batesian) on the variety of morphological, chemical, be­ Chemoecological studies include qualitative Of some ctenuchine species the larvae use mimicry. havioural and ecological features Ctenuchinae and quantitative analyses of sequestration of A Dycladia correbioides gathering pyrrolizidine PA-plants as primary host plants. This again provide, we expect to gain deep insight into eco­ plant chemicals and of volatiles emitted from alkaloids (e.g., heliotrine: D) from drying seeds of is a parallel to other Lepidoptera (Arctiinae, Additional morphological characters logical factors governing evolution of defensive Amycles affinis Autochloris jamsonis Heliotropium (B); C dihydropyrrolizine pheromone androconial organs as well as studies on host Danainae) and Coleoptera (Alticinae) which Expression of proboscis / palps / antennae / and sexual communication mechanisms and Diversity of wing patterns in Ctenuchinae component derived from PA; E Pseudosphex sp. plant relationships. gathering crystals of PAs from a dish gene-rates exciting evolutionary questions. various larval characters / pupal cocoons / ... strategies.