William L. Overal

Quantifying the biodiversity value of tropical primary, secondary, and plantation forests

Biodiversity loss from deforestation may be partly offset by the expansion of secondary forests and plantation forestry in the tropics. However, our current knowledge of the value of these habitats for biodiversity conservation is limited to very few taxa, and many studies are severely confounded by methodological shortcomings. We examined the conservation value of tropical primary, secondary, and plantation forests for 15 taxonomic groups using a robust and replicated sample design that minimized edge effects. Different taxa varied markedly in their response to patterns of land use in terms of species richness and the percentage of species restricted to primary forest (varying from 5% to 57%), yet almost all between-forest comparisons showed marked differences in community structure and composition. Cross-taxon congruence in response patterns was very weak when evaluated using abundance or species richness data, but much stronger when using metrics based upon community similarity. Our results show that, whereas the biodiversity indicator group concept may hold some validity for several taxa that are frequently sampled (such as birds and fruit-feeding butterflies), it fails for those exhibiting highly idiosyncratic responses to tropical land-use change (including highly vagile species groups such as bats and orchid bees), highlighting the problems associated with quantifying the biodiversity value of anthropogenic habitats. Finally, although we show that areas of native regeneration and exotic tree plantations can provide complementary conservation services, we also provide clear empirical evidence demonstrating the irreplaceable value of primary forests.

Comparative enzymology of venoms from stinging Hymenoptera

Venoms from 20 species of stinging Hymenoptera, including nine species of ants and nine species of social wasps, were quantitatively analyzed for the following enzymic activities: phospholipase A, hyaluronidase, lipase, esterase, protease, acid phosphatase, alkaline phosphatase and phosphodiesterase. Phospholipase and hyaluronidase were present in all the venoms, with activity levels generally higher among the wasps than the ants (P less than 0.05). Lipase was present in high activity in several social wasp venoms and one ant venom, in low levels in two other ant venoms and absent from four tested snake venoms. Two-carbon esterase activity was present in the venoms of five social wasps and one ant. Non-specific protease was present at very high activity levels in the venoms of an army ant species and was also present in the venoms of a social wasp and another ant. Acid phosphatase activity was present in eight of the nine ant venoms, but was essentially absent from all the social wasp venoms. Alkaline phosphatase activity was clearly detectable in the venoms of only two species of ants. Phosphodiesterase, an enzyme not previously detected in insect venoms, was present in the venoms of three closely related ant species. Venoms with generally high enzymic activities included those of Polistes infuscatus, Vespula (V.) squamosa and Pogonomyrmex badius; those with low activities included Dolichovespula maculata, Apoica pallens and Dasymutilla lepeletierii. The 20 venoms were ranked according to overall activity levels using the eight enzyme activities plus lethal, hemolytic and pain-inducing activities. They were also compared phylogenetically using these 11 activities.

Diversity and composition of Amazonian moths in primary, secondary and plantation forests.

The response of tropical fauna to landscape-level habitat change is poorly understood. Increased conversion of native primary forest to alternative land-uses, including secondary forest and exotic tree plantations, highlights the importance of assessing diversity patterns within these forest types. We sampled 1848 moths from 335 species of Arctiidae, Saturniidae and Sphingidae, over a total of 30 trap-nights. Sampling was conducted during the wet season 2005, using three light-traps at 15 sites within areas of primary forest, secondary forest and Eucalyptus urograndis plantations in northern Brazilian Amazonia. The Jari study region provides one of the best opportunities to investigate the ecological consequences of land-use change, and this study is one of the first to examine patterns of diversity for a neotropical moth assemblage in a human-dominated landscape in lowland Amazonia. We found that the three moth families responded consistently to disturbance in terms of abundance and community structure but variably in terms of species richness, in a manner apparently supporting a life-history hypothesis. Our results suggest that secondary forests and Eucalyptus plantations can support a substantial level of moth diversity but also show that these forest types hold assemblages with significantly distinct community structures and composition from primary forest. In addition, the ability of these converted land-uses to support primary forest species may be enhanced by proximity to surrounding primary forest, an issue which requires consideration when assessing the diversity and composition of mobile taxa in human-dominated landscapes.

Diversity and composition of fruit-feeding butterflies in tropical Eucalyptus plantations

Production landscapes are rarely considered as priority areas for biodiversity conservation in the tropics. Tree plantations have the potential to provide a conservation service in much of the humid tropics since they are rapidly increasing in extent and present less of a structural contrast with native vegetation than many more intensive agricultural land-uses. We used hierarchical partitioning to examine the factors that influence the value of large-scale Eucalyptus plantations for tropical fruit-feeding butterflies (Lepidoptera: Nymphalidae) in the Brazilian Amazon. We focused on evaluating the importance of landscape versus stand-level factors in determining the diversity and composition of butterfly assemblages, and how butterfly-environment relationships vary within and between subfamilies of Nymphalidae. Native understorey vegetation richness had the strongest independent effect on the richness, abundance and composition of all fruit-feeding butterflies, as well as a subset of species that had been recorded in nearby primary forests. However, overall patterns were strongly influenced by the most abundant subfamily (Satyrinae), and vegetation richness was not related to the abundance of any other subfamily, or non-Satyrinae species, highlighting the importance of disaggregating the fruit-feeding Nymphalidae when examining butterfly-environment relationships. Our results suggest that plantations can help conserve a limited number of forest species, and serve to highlight the research that is necessary to understand better the relationship between fruit-feeding butterflies and environmental variables that are amenable to management.

Biochemistry of termite defenses: Coptotermes, rhinotermes and Cornitermes species

Abstract 1. 1. The frontal gland secretion of soldiers of Coptotermes testaceus is dominated by hexadecanal and heptadecanal. 2. 2. Nonadecanoic acid is the major constituent present in the secretion of Rhinotermes marginalis. 3. 3. Soldiers of Cornitermes weberi produce phenylacetaldehyde, 2-piperidone and N- methyl -2- piperidone in their frontal glands, whereas those of C. ovatus and C. pugnax synthesize the lactone mellein. 4. 4. Both mellein and phenylacetaldehyde are deterrent to ants at low concentrations. 5. 5. The significance of these findings in terms of the comparative biochemistry of termite defenses is discussed.

Comparative lethality of venoms from stinging hymenoptera

The lethality to mice of the venoms from 7 species of ants, 7 species of wasps in the family Vespidae, 2 species of bees, and 1 species of solitary parasitic wasp are reported for the first time. The LD50 (24 hr) values ranged between a low of 0·25 mg/kg and a high of 71 mg/kg. Although venoms from congeneric species exhibited similar lethalities, no correlations between venom lethality and higher taxonomic groupings were evident. The results of this study reemphasise the fact that hymenopterous venoms are characterized more by their differences than by their similarities.

BIOFRAG - a new database for analyzing BIOdiversity responses to forest FRAGmentation

Habitat fragmentation studies have produced complex results that are challenging to synthesize. Inconsistencies among studies may result from variation in the choice of landscape metrics and response variables, which is often compounded by a lack of key statistical or methodological information. Collating primary datasets on biodiversity responses to fragmentation in a consistent and flexible database permits simple data retrieval for subsequent analyses. We present a relational database that links such field data to taxonomic nomenclature, spatial and temporal plot attributes, and environmental characteristics. Field assessments include measurements of the response(s) (e.g., presence, abundance, ground cover) of one or more species linked to plots in fragments within a partially forested landscape. The database currently holds 9830 unique species recorded in plots of 58 unique landscapes in six of eight realms: mammals 315, birds 1286, herptiles 460, insects 4521, spiders 204, other arthropods 85, gastropods 70, annelids 8, platyhelminthes 4, Onychophora 2, vascular plants 2112, nonvascular plants and lichens 320, and fungi 449. Three landscapes were sampled as long-term time series (>10 years). Seven hundred and eleven species are found in two or more landscapes. Consolidating the substantial amount of primary data available on biodiversity responses to fragmentation in the context of land-use change and natural disturbances is an essential part of understanding the effects of increasing anthropogenic pressures on land. The consistent format of this database facilitates testing of generalizations concerning biologic responses to fragmentation across diverse systems and taxa. It also allows the re-examination of existing datasets with alternative landscape metrics and robust statistical methods, for example, helping to address pseudo-replication problems. The database can thus help researchers in producing broad syntheses of the effects of land use. The database is dynamic and inclusive, and contributions from individual and large-scale data-collection efforts are welcome.

Systematic implications of the exocrine chemistry of some Hypoclinea species

Abstract The exocrine compounds produced by several species of Hypoclinea were analysed and compared to those identified in species in other genera of the ant subfamily Dolichoderinae. Two new natural products, 2-hydroxy-6-methylaceto-phenone and 2-acetoxy-6-methylacetophenone, were identified as anal gland products of three Hypoclinea species. The significance of two “forms” of H. bidens possessing completely different glandular secretions is discussed, and the relationship of the genera Hypoclinea and Dolichoderus is explored in terms of the exocrine chemistry of species in these two dolichoderine taxa.

Exocrine chemistry of the monotypic ant Genus Gigantiops

Abstract 1. 1. The mandibular gland secretion of the formicine ant Gigantiops destructor is dominated by 3-octane with 3-octanol and 3-heptanone constituting minor concomitants. 2. 2. n-Nonane and 2-tridecanone constitute the major Dufours gland products, being accompanied by n-octane, n-undecane, 2-pentadecanone, nnonyl acetate and n-decyl acetate. 3. 3. No demonstrable behavior was elicited in workers of this formicine by extracts of either gland. 4. 4. The exocrine chemistry of G. destructor is comparatively analyzed in terms of the position of this monotypic genus in the subfamily Formicinae.