Changes in leaf chlorophyll content associated with flowering and its role in the diversity of phytophagous insects in a tree species from a semiarid Caatinga.

Phytophagous insects choose their feeding resources according to their own requirements, but their feeding preferences in the semiarid Caatinga have rarely been studied. Flowering trees leads to a greater diversity of flower visitors and their predators in the host plant, but little is known about why the diversity of phytophagous insects not associated with flowers is also increased. The purpose of this study was to evaluate the diversity of sap-sucking, wood-boring and leaf-chewing insects associated with leaf chlorophyll content in flowering and non-flowering plants of Poincianella pyramidalis, an endemic tree of Caatinga. We used a leaf chlorophyll index (LCI) as a surrogate for resource quality, and an entomological umbrella to collect phytophagous insects. We show that trees which bloomed demonstrated higher chlorophyll content, greater abundance and a significant difference in the composition of phytophagous insect species when compared to non-flowering trees (p < 0.05). The results suggest that not only the presence of flowers themselves, but also the higher nutritional quality of leaf tissue, can explain the differences in species diversity and abundance of phytophagous insects. Exceptional flowering trees in the Caatinga area studied may thus act as spots of high quality resources, favouring changes in the diversity of insects in this environment.

Sperm depletion: a cost for single mated females of Podisus nigrispinus (Dallas, 1851) (Heteroptera: Pentatomidae)

The aim of this work was to test if egg viability of polyandrous females was increased with increasing number of matings. Longevity and reproductive output of females of the predatory stinkbug Podisus nigrispinus that were allowed to mate for 0, 1, 2, 3 times or were in the continuous presence of the same male was evaluated. Polyandry resulted in diminished sperm depletion. Females that had mated three times or that were in continuous presence of a male produced more offspring than females that mated once or twice throughout their lifetime. There was a negative correlation of mating history on female longevity. Results indicated that remating, either with same male or with different males were crucial for maximization of the reproductive success of females.

Entre os heterópteros, o declínio da concentração de esperma pode ser um fator limitante para o sucesso reprodutivo desses insetos. Acasalamentos múltiplos conferem um reabastecimento de esperma e podem permitir um aumento do valor adaptativo das fêmeas. Neste estudo foi testada a hipótese de que a poliandria aumenta a viabilidade dos ovos. A longevidade de fêmeas de Podisus nigrispinus, bem como seus parâmetros reprodutivos em resposta a diferentes números de acasalamentos (0, 1, 2, 3 ou em coabitação com o mesmo macho) foi avaliada. Esse percevejo vem sendo usado em programas de controle biológico de pragas em reflorestamentos de Eucalipto no Brasil. Apesar da diminuição no tempo de sobrevivência das fêmeas, acasalamentos múltiplos mantiveram a viabilidade dos ovos e o período reprodutivo das fêmeas, permitindo um maior número de descendentes produzidos. Tais resultados indicam que um número mínimo de três acasalamentos antes da primeira postura permite uma maximização do sucesso reprodutivo dessa espécie.

Polyandrous behavior in Cerconota anonella Sepp (Lepidoptera: Oecophoridae)

Entre insetos, o comportamento poliândrico é comum e tem significado importante no sucesso reprodutivo das fêmeas. Este trabalho objetivou estudar a freqüência de acasalamentos, em laboratório, da broca-da-graviola, Cerconota anonella Sepp, de forma a determinar se o comportamento poliândrico nessa espécie é comum. Cerca de 47% das fêmeas acasalaram mais de uma vez, porém houve diferenças no período das cópulas (precoce ou tardia). No geral fêmeas precoces foram mais freqüentes do que fêmeas tardias (P < 0.001, teste Binomial). Tais resultados sugerem que a poliandria em condições de campo pode ser possível em C. anonella.

Polyandrous behavior in Cerconota anonella Sepp (Lepidoptera: Oecophoridae).

Among insects polyandrous behavior is common and plays an important role in female reproductive output. The present study aimed to evaluate the mating frequency of the moth Cerconota anonella Sepp under laboratory conditions and to verify if polyandrous behavior is common in this species. Approximately 47% of females mated more than once. However they presented differences in the mating period (early or late). In general, precocious females were more frequent than late females (P < 0.001, Binomial test). Such results suggest that polyandry in C. anonella may be common in the field.