Composição e sazonalidade de borboletas frugívoras no cerrado, com ênfase na relação fenológica entre Eunica bechina (Nymphalidae: Biblidinae) e sua planta hospedeira Caryocar brasiliense (Caryocaraceae) / Composition and seasonality of fruit-feeding butterflies in the cerrado savanna, with emphasis on the phenological relationship between Eunica bechina (Nymphalidae: Biblidinae) and its host plant Caryocar brasiliense (Caryocaraceae)

Danilo Germano Muniz da Silva

In many tropical environments, rainy and dry seasons alternate. The dryer season has decreased leaf availability and the nutritional quality of leaves is also low - thus it is an unfavorable period for herbivorous insects and generates seasonal oscillations in their populations. The cerrado is a neotropical seasonal biome characterized by a hot/rainy and a cold/dry season. Leaf production is generally concentrated in the rainy season, which is the favorable period for herbivorous insects such as butterflies. In its larval stage, butterflies are voracious and specialized herbivores, and their populations commonly oscillate according to the availability of adequate leaves for immature feeding. Butterflies can be categorized in two functional guilds according to the food resources utilized by the adults: one group feeds on flower nectar, whereas another group of species feed on the liquids from rotting fruits, carcasses and excrements, and also plant sap. The latter group is known as fruit-feeding butterflies. Fruit-feeding butterfly guild has been widely used in studies of community ecology because they are easily captured using traps with fermented fruit, and also easily identified. Surprisingly, however, fruit-feeding butterflies have rarely been studied in seasonal, open environments. In this dissertation we investigated the seasonality of fruit-feeding butterflies in the cerrado sensu stricto. In the first chapter we decribe the composition of the community, changes through the year, and oscillations in its abundance. The greatest abundance occurred in the mid rainy season, while richness peaked at the late rainy season. Satyrini was the most abundant group in the rainy period (mainly Yphthimoides manasses), whereas Biblidinae (mainly Hamadryas februa) was more common in the dry season. In the second chapter we analyze in detail the phenological relationship between the butterfly Eunica bechina and its hostplant Caryocar brasiliense. The larvae feed only on the young leaves of C.brasiliense that bear extrafloral nectaries, which attract ants that patrol the plant and attack E. bechina larvae. We observed the larger occurrence of larvae in the early rainy season, when most young leaves are produced. Eggs and larvae where present at almost all sampling months, except in the late rainy season. We suggest that this is a period of reproductive inactivity in the species, due to the low availability of young leaves.

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