Ant–herbivore interactions in an extrafloral nectaried plant: are ants good plant guards against curculionid beetles?

Extrafloral nectary drinking ants are known as effective plant guards, but some herbivores may circumvent ant attacks by foraging on different plant parts or presenting adaptations to avoid ant predation. Here we experimentally investigated the effect of Camponotus blandus on the florivory of the extrafloral nectaried shrub Banisteriopsis malifolia; and a possible spatial segregation between ants and herbivores (leaves and flowers). Flower buds are attacked by Anthonomus weevils. Results revealed no significant influence of C. blandus on the reduction of florivory. Adult Anthonomus are hard-bodied and were immune to ant bites; larvae are endophytic, so protected from ants. Ants and adult beetles were concentrated in different plant parts (leaves and flowers, respectively) so restraining the probability of encounters. Our results indicate that the system C. blandus–Anthonomus–B. malifolia is not stable, as ants receive extrafloral nectar, but are unable to protect the plant against weevils.     

Variation in ant populations with elevation, tree cover, and fire in a pinyon-juniper–dominated watershed

Climate change and fire suppression have facilitated expansion of pinyon-juniper woodlands into sagebrush-steppe ecosystems of the Great Basin, USA, resulting in a loss of biological diversity. To assess the effects of using prescribed fire in restoration efforts, ant abundance, species richness, and composition were examined pre- and post-burn along the elevation and tree cover gradients encompassed by a pinyon-juniper woodland in a central Nevada watershed. Ants were sampled using pitfall traps in 6 sites for the elevation study and in 2 sites for the tree cover study, representing paired burn and control sites in a randomized block design. Vegetation and ground cover variables were also sampled to determine how variation in ant populations was correlated with differences in vegetation and ground cover. Ant species richness remained unchanged for all treatments. Tree cover had no significant effect on ant populations. Significantly more ants were trapped after the burn treatment on burn plots. Variation in ant populations was not directly correlated with any of the vegetation or ground cover variables. According to ANOVA and multivariate analyses, elevation had the greatest effect on changes in ant communities, likely due to increased moisture availability. Our results suggest that management for conservation of sagebrush-steppe ecosystems in this and similar watersheds should include a range of elevations to ensure maximum ant species diversity.     

Adult butterfly feeding–nectar flower associations: constraints of taxonomic affiliation,butterfly, and nectar flower morphology

Butterfly–flower morphological interrelationships were investigated for 108 butterfly species and 20 plants at Nagpur, India. Distinct clusters of higher taxa (families) are disclosed for butterfly morphology and significant morphological and taxonomic associations occur in nectar exploitation. Flower corolla depth generally restricts exploitation by butterflies in relation to proboscis length and butterflies with high wing load indices bias their feeding to plants with massed flowers. However, important exceptions emerge; also, a substantial number of butterflies feed on plants with massed flowers though their proboscises are of marginal length for corolla depths. These butterfly species are significantly smaller, lighter, with lower wing loading and shorter proboscis indices than species which easily access the same flowering plant species. It is suggested that small size and short proboscises could give them a competitive advantage (increased rate of nectar uptake) for exploiting nectar in such situations. The significance of the findings for conservation is discussed.     

Using short-term surveys and mark–recapture to estimate diversity and population size of orchid bees in forest formations of the Brazilian savanna

Studies on the diversity and population dynamics of euglossine bees in forest formations of the Brazilian savanna can be notably informative considering that most species are forest-dependent. The current study aimed to estimate the diversity and population size of euglossine bees using short-term surveys and the mark–recapture method. We also compared short-term surveys with monthly surveys over a 1-year period (long-term surveys) to assess the species diversity. The study occurred in seven forest formations of the Brazilian savanna. We collected 14 species and marked 375 males but recaptured only 23 (6.1%). The population size of Euglossa bees ranged from 111.1 ± 34.4 to 1384.5 ± 384.6 males. The diversity indices achieved through the short-term surveys were similar to or higher than those obtained from long-term studies. The low recapture rate of euglossine males seems to be the result of their long-distance dispersal capacity. We also proposed that short-term surveys be viewed as a favourable alternative to long-term studies on diversity estimation and that euglossine bees can occur in small populations in some forest formations studied.     

Fly parasitism in Papuan frogs,with a discussion of ecological factors influencing evolution of life‐history differences

Dipteran parasitism of frogs in the Papuan region is described and aspects of the ecological interaction are detailed. The fly involved, Batrachomyia krausi, is the largest known member of an otherwise Australian genus. Larvae of this species develop in the lateral lymph sacs of frogs of the genus Rana, feed on host blood tissues, occur with high incidence and moderate intensity, yet exhibit minimal virulence. Minimal virulence and high infestation rate seen in this host–parasite system contrast with those reported for Australian congeners. These differences are hypothesized to derive from interaction of the large size of the Papuan parasite with its phylogenetically constrained life‐history. Differences in virulence exhibited between parasitic chloropids versus calliphorids and sarcophagids are discussed as consistent with ecological predictions based on parasite transmission dynamics.