Bionomy of Hermetia illucens (Diptera: Stratiomyidae) on Decomposing Swine Carcass in an Urban Area of Central Amazon.

Biological data on development of Hermetia illucens (Linnaeus, 1758) is useful to calculate the postmortem interval (PMI), thus being important for solving crimes. We aimed at gathering bionomic information on H. illucens, during the decomposition of a Sus scrofa, in the urban zone of Manaus, Amazonas State. Mature females and eggs were collected on the swine carcass. After hatching under natural conditions, larvae were observed daily. Different instars were fixed in ethylic alcohol to determine instar duration by the evaluation of the frequency distribution of cephalic capsule measurements and the principal components analysis (PCA). Females laid 620-700 eggs per posture in concealed locations preferentially, such as cranial cavities and slots on the metal cage. The larvae were found under the swine skin and on bones. After feeding, the larvae of H. illucens began to move slowly to pupate, did not seek for drier sites to do it, and buried themselves into the carcass instead. Pupae were observed as of the 60th day after death. H. illucens completed its life cycle in 53-82 d, which encompassed six larval instars and the pupa. About 93% of the eggs hatched, 11% reached the adult stage and the sex ratio was 0.49. Our results are complementary to the biological information of this species in Central Amazon, since most of the data were not known yet. This should render PMI calculation more accurate, even for corpses in advanced decomposition stages, as H. illucens spends relatively more time on the carcasses than most dipterans.

Fresh and Dry Mass Estimates of Hermetia illucens (Linnaeus, 1758) (Diptera: Stratiomyidae) Larvae Associated with Swine Decomposition in Urban Area of Central Amazonia.

Information on biomass is substantial for calculating growth rates and may be employed in the medicolegal and economic importance of Hermetia illucens (Linnaeus, 1758). Although biomass is essential to understanding many ecological processes, it is not easily measured. Biomass may be determined by directly weighing or indirectly through regression models of fresh/dry mass versus body dimensions. In this study, we evaluated the association between morphometry and fresh/dry mass of immature H. illucens using linear, exponential, and power regression models. We measured width and length of the cephalic capsule, overall body length, and width of the largest abdominal segment of 280 larvae. Overall body length and width of the largest abdominal segment were the best predictors for biomass. Exponential models best fitted body dimensions and biomass (both fresh and dry), followed by power and linear models. In all models, fresh and dry biomass were strongly correlated (>75%). Values estimated by the models did not differ from observed ones, and prediction power varied from 27 to 79%. Accordingly, the correspondence between biomass and body dimensions should facilitate and motivate the development of applied studies involving H. illucens in the Amazon region.

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.