Comparative ecology and mimetic relationships of Ithomiine butterflies in Eastern Ecuador / boyce Alexander Drummond.

Tese (Ph.D.) University of Florida, 1976

Butterflies of the subfamily Ithomiinae (Lepidoptera, Ithomiidae) are among the most conspicuous and abundant flying insects of neotropical forests yet they have received little attention from ecologists and their biology is not well known. A comprehensive ecological study of a rich (53 species) ithomiine community (in lowland rainforest at Limoncocha, on the Rio Napo, eastern Ecuador) was combined with an extensive search of the literature to characterize this subfamily in ecological terms. Ithomiines usually exhibit clumped distribution, even within seemingly homogeneous forests, where their responses to gradients of light and relative humidity result in transient concentrations that crest and ebb through time. Ithomiines are long-lived, with low daily rates of oviposition and adult-financed egg production. The early morning visits of ithomiine males to white flowers fit the syndrome of crepuscular pollination and may represent a coevolved relationshif. Females feed on detritus from which they apparently obtain the nitrogen needed for continuous egg production. Courtship behavior is species-specific and involves two categories of mate-locating behavior by males, "display perching" and "patrol perching. " The oviposition strategies of ithomiine females vary greatly and four modes of oviposition behavior are recognized.The adaptive significance of extended copulation in butterflies is discussed. Local populations of most ithomiine species appear to be narrowly specific in larval foodplant utilization, and the high diversity of the ithomiine community is probably due in large part to the high diversity of the larval foodplants (Solanaceae) in tropical forests. Larval development time depends on the mechanical and chemical characteristics of the foodplant, but the average generation time is about 28 to 30 days. Juvenile ithomiines display great interspecific variation in morphology in all 1ife stages. The similarity of the previously undescribed larva of Melinaea menophilus (Ithomiidae) to larvae of other primitive ithomiines and to larvare of the Danaidae provides new evidence for the relationship between the two families. A nine-month censusing program at Limoncocha revealed that the ithomiine adult community appears to be quite stable in relative composition of mimetic patterns, age distribution, species diversity (H'), and equitability (J'). Larval foodplants are greatly under-utilized at Limoncocha and intensive parasitism and predation of juvenile stages appear to be controlling the population sizes of most ithomiine species although the overall abundance of the ithomiine community may be severely depressed by the indiscriminate adult mortality resulting from violent storms and periods of heavy rainfall. .