Amides have been recognized as potent insecticidal natural products but, despite their variety of targets and mechanisms of action, their metabolic fate in insects is virtually unknown. The currently accepted hypothesis is that specialist herbivores are capable of biotransforming xenobiotics rendering them more polar and excretable while generalist insects do not have comparable capacity. The leaves from Piper tuberculatum, rich in insecticide amides, were offered to two insect species found on Piper leaves under natural conditions and also to four generalist grasshoppers in order to compare their capacity of biotransforming xenobiotics. The amides 1-7 were identified in the P. tuberculatum leaves and their corresponding carboxylic acids 8-13 were detected in frass samples of two host insects suggesting that these species promote the amides hydrolysis. The four generalist grasshoppers when offered P. tuberculatum leaves, starved to death after 72 h, indicating a strong antifeedant activity of P. tuberculatum leaves.

As espécies de Piperaceae têm sido posicionadas entre as angiospermas basais e são frequentemente encontradas em habitats diversificados que incluem matas ciliares, vegetação secundária e campos rupestres. As espécies de Piper possuem hábitos de plantas herbáceas, arboretos e trepadeiras enquanto que, no caso de Peperomia, é freqüente o hábito de epífitas e suculentas. As classes de metabólitos secundários que caracterizam espécies de Piperaceae são amidas, fenilpropanóides/lignóides e cromenos, além de diversos outros de origem biossintética mista de menor representatividade. Apesar de muitos desses possuírem atividades inseticidas, diversos insetos fitófagos, alguns considerados pragas de importância econômica, foram observados alimentando-se de espécies de Piperaceae. Neste trabalho são relatadas as preferências alimentares de quatorze espécies fitófagas de Coleoptera, Lepidoptera e Hemiptera sobre aproximadamente cinqüenta espécies de Piperaceae observadas em São Paulo, SP, Brasil, durante um período de quatro anos.

Piperaceae species have been placed among the basal angiosperm and are adapted to a variety of habitats including moist forests, secondary vegetation and dry high lands. The major anatomical/morphology features are of small trees, vines, and shrubs for Piper species, while the epiphytic and succulent characteristics are predominant forms among Peperomia species. Their secondary chemistry can be mostly represented by amides, phenylpropanoids/lignoids, and chromenes in addition to a phletoria of biosynthetically mixed-origin secondary compounds. Although several amides and lignans are known as insecticides, several phytophagous insects, among which some considered pests of economic importance, have been observed feeding vigorously on Piperaceae species. Herein we describe the feeding preferences of fourteen phytophagous species of Coleoptera, Lepidoptera and Hemiptera over approximately fifty Piperaceae species observed in São Paulo, SP, Brazil, in a long-term basis.

Larvae of Stilpnonotus postsignatus Fairmaire, 1889 were collected inside a hard log in Peruíbe, São Paulo, Brazil; reared adults were identified. A description of the larva, pre-pupa and pupa are provided with ilustrations.