Contrasting effects of sampling scale on insect herbivores distribution in response to canopy structure.

Species diversity of insect herbivores associated to canopy may vary local and geographically responding to distinct factors at different spatial scales. The aim of this study was to investigate how forest canopy structure affects insect herbivore species richness and abundance depending on feeding guilds' specificities. We tested the hypothesis that habitat structure affects insect herbivore species richness and abundance differently to sap-sucking and chewing herbivore guilds. Two spatial scales were evaluated: inside tree crowns (fine spatial cale) and canopy regions (coarse spatial scale). In three sampling sites we measured 120 tree crowns, grouped n five points with four contiguous tree crowns. Insects were sampled by beating method from each crown and data were summed up for analyzing each canopy region. In crowns (fine spatial scale) we measured habitat tructure: trunk circumference, tree height, canopy depth, number of ramifications and maximum ramification level. In each point, defined as a canopy region (coarse spatial scale), we measured habitat structure using a vertical cylindrical transect: tree species richness, leaf area, sum of strata heights and maximum canopy height. A principal component analysis based on the measured variables for each spatial scale was run to estimate habitat structure parameters. To test the effects of habitat structure upon herbivores, different general linear models were adjusted using the first two principal components as explanatory variables. Sap-sucking insect species richness and all herbivore abundances increased with size of crown at fine spatial scale. On the other hand, chewer species richness and abundance increased with resource quantity at coarse scale. Feeding specialization, resources availability, and agility are discussed as ecological causes of the found pattern.

Contrasting effects of sampling scale on insect herbivores distribution in response to canopy structure

Species diversity of insect herbivores associated to canopy may vary local and geographically responding to distinct factors at different spatial scales. The aim of this study was to investigate how forest canopy structure affects insect herbivore species richness and abundance depending on feeding guilds´ specificities. We tested the hypothesis that habitat structure affects insect herbivore species richness and abundance differently to sap-sucking and chewing herbivore guilds. Two spatial scales were evaluated: inside tree crowns (fine spatial scale) and canopy regions (coarse spatial scale). In three sampling sites we measured 120 tree crowns, grouped in five points with four contiguous tree crowns. Insects were sampled by beating method from each crown and data were summed up for analyzing each canopy region. In crowns (fine spatial scale) we measured habitat structure: trunk circumference, tree height, canopy depth, number of ramifications and maximum ramification level. In each point, defined as a canopy region (coarse spatial scale), we measured habitat structure using a vertical cylindrical transect: tree species richness, leaf area, sum of strata heights and maximum canopy height. A principal component analysis based on the measured variables for each spatial scale was run to estimate habitat structure parameters. To test the effects of habitat structure upon herbivores, different general linear models were adjusted using the first two principal components as explanatory variables. Sap-sucking insect species richness and all herbivore abundances increased with size of crown at fine spatial scale. On the other hand, chewer species richness and abundance increased with resource quantity at coarse scale. Feeding specialization, resources availability, and agility are discussed as ecological causes of the found pattern.

La diversidad de especies de insectos herbívoros asociados con el dosel puede variar geográficamente y responder a distintos factores a diferentes escalas espaciales. El objetivo de este estudio fue investigar cómo la estructura del dosel afecta la riqueza de especies de insectos herbívoros y la abundancia en función la especialización alimenticia. Se evaluó la hipótesis que propone que la estructura del hábitat afecta en forma diferente la riqueza y abundancia de especies de insectos que se alimentan de savia y la de especies herbívoras masticadoras. Dos escalas espaciales fueron evaluadas: el interior de las copas de árboles (escala fina) y regiones del dosel (escala gruesa). En tres sitios de muestreo medimos 120 copas de árboles, agrupadas en cinco puntos con cuatro copas de árboles contiguas. Los insectos fueron muestreados golpeando las copas y los datos fueron sumados para analizar cada región del dosel. En las copas (escala espacial fina) medimos la estructura del hábitat: circunferencia del tronco, altura del árbol, profundidad del dosel, número de ramificaciones y máximo nivel de ramificación. En cada punto, definiendo una región del dosel (escala gruesa), medimos la estructura del hábitat usando un transecto cilíndrico vertical: riqueza de especies árboles, área foliar, sumatoria de altura de los estratos y máxima altura del dosel. Fue realizado un análisis de componentes principales basado en las variables medidas para cada escala espacial para estimar los parámetros de la estructura del hábitat. Para probar los efectos de la estructura del hábitat sobre los herbívoros, se ajustaron diferentes modelos lineares generales usando estos componentes principales como variables causales. La riqueza de especies chupadoras de savia y la abundancia de todas las especies herbívoras se incrementaron con el tamaño de la copa en la escala espacial final. Por otro lado, la riqueza y abundancia de especies masticadoras incrementaron con la complejidad de la estructura del hábitat en la escala más gruesa. La especialización alimenticia, la disponibilidad de recursos y la movilidad son propuestas como los factores ecológicos que explican los patrones observados.

Ethanol fuel improves arthropod capture in pitfall traps and preserves DNA.

We tested the value of ethanol fuel as a killing solution in terms of sampling efficiency (species richness and accumulated abundance) and DNA preservation of Ensifera ground-dwelling specimens. Sampling efficiency was evaluated comparing abundance and species richness of pitfall sampling using 100% ethanol fuel, with two alternative killing solutions. We evaluated the DNA preservation efficiency of the killing solutions and of alternative storage solutions. Ethanol fuel was the most efficient killing solution, and allowed successful DNA preservation. This solution is cheaper than other preserving liquids, and is easily acquired near field study sites since it is available at every fuel station in Brazil and at an increasing number of fuel stations in the U.S. We recommend the use of ethanol fuel as a killing and storage solution, because it is a cheap and efficient alternative for large-scale arthropod sampling, both logistically and for DNA preservation. For open habitat sampling with high day temperatures, we recommend doubling the solution volume to cope with high evaporation, increasing its efficacy over two days.

Two new species of Phalangopsis Serville, 1831 (Orthoptera: Grylloidea: Phalangopsidae) from Brazilian Amazon Forest

We describe here two new species of the genus Phalangopsis Serville, 1831 from the Brazilian Amazon Forest. The male genitalia and the female copulatory papilla were described, and a combination of diagnostic characteristics was given to separate both new species from the other described species. The principal morphological characteristics of this genus were discussed.

Aqui foram descritas duas espécies novas do gênero Phalangopsis Serville, 1831 da Floresta Amazônica brasileira. A genitália masculina e a papila copulatória feminina são descritas, bem como uma combinação de características diagnósticas para separar ambas as novas espécies das outras espécies descritas. As principais características morfológicas foram discutidas.

Two new species of Phalangopsis Serville, 1831 (Orthoptera: Grylloidea: Phalangopsidae) from Brazilian Amazon Forest.

We describe here two new species of the genus Phalangopsis Serville, 1831 from the Brazilian Amazon Forest. The male genitalia and the female copulatory papilla were described, and a combination of diagnostic characteristics was given to separate both new species from the other described species. The principal morphological characteristics of this genus were discussed.

A new species of Laranda Walker 1869 (Orthoptera: Grylloidea, Phalangopsidae) from remnant patches of the Brazilian Atlantic Forest.

The genus Laranda has six described species and is confined to South and Southeast of Brazil. We describe a new species and discuss the biology and distribution of the genus. The new species can be distinguished from its known congeners by the following characteristics: absence of yellow spots on pronotum and base of posterior tibiae; female copulatory papilla: sclerotization in dorsal view forming opposing acute angles, apical lobes narrow and small; male genitalia: pseudepiphallic median process short and wide; pseudepiphallic paramere with apex incurved and ectophallic fold surpassing apex of the parameres. The genus is distributed within the Atlantic Forest biome; the new species is found on tree trunks, as well as on forest leaf litter.

A new species of Laranda Walker 1869 (Orthoptera: Grylloidea, Phalangopsidae) from remnant patches of the Brazilian Atlantic Forest / Uma nova espécie de Laranda Walker 1869 (Orthoptera: Grylloidea, Phalangopsidae) de remanescentes da Mata Atlântica brasileira

The genus Laranda has six described species and is confined to South and Southeast of Brazil. We describe a new species and discuss the biology and distribution of the genus. The new species can be distinguished from its known congeners by the following characteristics: absence of yellow spots on pronotum and base of posterior tibiae; female copulatory papilla: sclerotization in dorsal view forming opposing acute angles, apical lobes narrow and small; male genitalia: pseudepiphallic median process short and wide; pseudepiphallic paramere with apex incurved and ectophallic fold surpassing apex of the parameres. The genus is distributed within the Atlantic Forest biome; the new species is found on tree trunks, as well as on forest leaf litter.

O gênero Laranda possui seis espécies descritas e está confinado ao Sul e Sudeste do Brasil. Neste trabalho é descrita uma nova espécie, e a biologia e a distribuição do gênero são discutidas. A nova espécie pode ser distinguida das demais espécies do gênero pelas seguintes características: ausência de manchas amarelas no pronoto e base das tíbias posteriores; papila copulatória da fêmea: esclerotização em vista dorsal formando ângulos agudos opostos e lobos apicais estreitos e pequenos; genitália do macho: processo mediano do pseudepifalo curto e largo; parâmero pseudepifálico com ápice curvado e dobra ectofálica ultrapassando o ápice dos parâmeros. O gênero se distribui dentro do bioma Mata Atlântica; a nova espécie é encontrada sobre troncos de árvores, bem como sobre serrapilheira florestal.

Aprimoramento da amostragem de grilos de serapilheira (Orthoptera: Gryllidae) por armadilha / Improving litter cricket (Orthoptera: Gryllidae) sampling with pitfall traps

Amostram-se grilos de serapilheira com armadilhas enterradas (pitfall). No entanto, algumas espécies são sub-amostradas, por que alguns indivíduos conseguem fugir da armadilha. Neste trabalho sugerimos a substituição da solução aquosa de detergente, por uma solução de formol-glicerina-álcool, para aumentar a eficiência da amostragem. Testamos se: (i) formol reduz a fuga de grilos; (ii) formol é repelente para os grilos. Foram instaladas 80 armadilhas, formando pares formol-detergente e detergente-detergente, com 20 cm entre armadilhas dentro do par, e 3 m entre pares. Foram coletados 105 indivíduos, sendo 29 adultos, de nove espécies, em três grupos taxonômicos: Phalangopsinae, Trigonidiinae e Brachytrupinae. Tanto o número de adultos quanto de ninfas capturados nas armadilhas com detergente não foi afetado pela proximidade de armadilha com formol. Nos pares formol-detergente, o número de adultos em formol foi maior que em detergente, enquanto o número de ninfas não foi diferente. Assim, formol não foi repelente nem para adultos nem para ninfas de grilos. As armadilhas com formol foram mais eficientes, por reterem mais adultos do que as com detergente, devido ao efeito de knock-down. As ninfas não foram afetadas porque sua fuga do detergente já é reduzida, devido a seu tamanho reduzido e menor esclerotização. Tamanho menor implica saltos menores, insuficientes para o escape. Esclerotização menor implica maior permeabilidade, de forma que uma vez que a ninfa cai na armadilha, ela não consegue mais fugir.

Pitfall traps are used to sample litter inhabiting crickets, but some species are underestimated, because captured individuals escape from the trap. Here we suggest the substitution of aqueous detergent killing solution by formol-glicerin-alcohool solution, to increase sampling efficiency. We tested two hypotheses: (i) formol solution reduces the escape of crickets from the traps; (ii) formol solution is repellent. We arranged 80 traps in pairs of traps formol/detergent and detergent/detergent, 20 cm between traps within pairs, and 3 m between pairs. We collected 105 cricket individuals, being 29 adults, from nine species, in three taxonomic groups: Phalangopsinae, Trigonidiinae, and Brachytrupinae. Capture of both adults and nymphs was not affected by proximity of formol solution traps. In formol-detergent pairs, formol traps captured more adult individuals than detergent traps, but the number of nymphs did not differ. Therefore, formol was not repellent neither for adults nor nymphs. Traps with formol were more eficient, because they retained more adults than those with detergent, because of knock-down effect. Nymphs were not affected by the killing solution because their escape frequency is already low, due to their tiny size and reduced sclerotization. Tiny size implies short jumps, insuficient to escape. Reduced sclerotization implies greater permeability, so that once fallen into the trap, nymphs cannot escape any more.

Why do male Xylographus contractus Mellié (Coleoptera: Ciidae) present abdominal fovea? Evidence of sexual pheromone secretion / Por que machos de Xylographus contractus Mellié (Coleoptera: Ciidae) apresentam fóvea abdominal? Evidências de secreção de feromônio sexual

Most male ciids present a fovea in the first urosternite. We tested two alternative hypotheses for the function of male abdominal fovea in Xylographus contractus Mellié: (i) the fovea secretes sexual pheromone, and (ii) the fovea secretes aggregation pheromone. For this, 59 specimens were submitted, separately, to two stimuli (fovea extracts and control) in an y-shaped glass olfactometer. For the analyses, we considered the 47 individuals that moved toward one of the longer olfactometer branches. The probability of moving toward the fovea extract was greater for females than for males (chi2 = 3.94, P = 0.047). The proportion of males that moved toward any of the olfactometer branches was the same (chi2 = 0.29, P = 0.59). We concluded that the male's abdominal fovea secretes a sexual pheromone and that there is no aggregation pheromone being secreted by this structure. We suggested that this sexual pheromone is used for short-range communication, acting in pre-copulatory courtship.

A maioria dos machos de ciídeos possuem uma fóvea no primeiro urosternito. Foram testadas duas hipóteses alternativas para explicar a função da fóvea abdominal em machos de Xylographus contractus Mellié: (i) a fóvea secreta feromônio sexual, e (ii) a fóvea secreta feromônio de agregação. Para isso, avaliou-se a resposta de 59 indivíduos, separadamente, a dois estímulos olfativos (extrato da fóvea e controle) em olfatômetro tipo Y. Nas análises, consideraram-se as respostas dos 47 indivíduos que se dirigiram a um dos braços do olfatômetro. A probabilidade de se deslocar em direção ao extrato de fóvea foi maior para fêmeas do que para machos (chi2 = 3,94, P = 0,047). A proporção de machos que se dirigiram para cada um dos braços do olfatômetro foi a mesma (chi2 = 0,29, P = 0,59). A fóvea abdominal dos machos secreta feromônio sexual, não sendo secretado nenhum feromônio de agregação por essa mesma estrutura. Sugere-se que o feromônio sexual seja usado em comunicação a curta distância, mediando mecanismos pré-copulatórios.