Estimating retention benchmarks for salvage logging to protect biodiversity.

Forests are increasingly affected by natural disturbances. Subsequent salvage logging, a widespread management practice conducted predominantly to recover economic capital, produces further disturbance and impacts biodiversity worldwide. Hence, naturally disturbed forests are among the most threatened habitats in the world, with consequences for their associated biodiversity. However, there are no evidence-based benchmarks for the proportion of area of naturally disturbed forests to be excluded from salvage logging to conserve biodiversity. We apply a mixed rarefaction/extrapolation approach to a global multi-taxa dataset from disturbed forests, including birds, plants, insects and fungi, to close this gap. We find that 75 ± 7% (mean ± SD) of a naturally disturbed area of a forest needs to be left unlogged to maintain 90% richness of its unique species, whereas retaining 50% of a naturally disturbed forest unlogged maintains 73 ± 12% of its unique species richness. These values do not change with the time elapsed since disturbance but vary considerably among taxonomic groups.

Species Specificity of the Putative Male Antennal Aphrodisiac Pheromone in Leptopilina heterotoma, Leptopilina boulardi, and Leptopilina victoriae.

Male antennal aphrodisiac pheromones have been suggested to elicit female receptiveness in several parasitic Hymenoptera, including Leptopilina boulardi. None of the proposed pheromones, however, has been fully identified to date. It is also unknown whether these antennal pheromones are species specific, because the species specificity of mate recognition and courtship elicitation in Leptopilina prevented such experiments. In this study we present an experimental design that allows the investigation of the species specificity of the putative male aphrodisiac pheromone of L. heterotoma, L. boulardi, and L. victoriae. This is achieved by chemical manipulation of the odour profile of heterospecific females, so that males perceive them as conspecifics and show antennal courtship behaviour. Males courted the manipulated heterospecific females and antennal contact between the male and the female was observed. However, males elicited receptiveness only in conspecific females, never in the manipulated heterospecific females. Chemical analysis showed the presence of species specific unsaturated hydrocarbons on the antennae of males. Only trace amounts of these hydrocarbons are found on the antennae of females. Our results are an important step towards the understanding and identification of antennal pheromones of parasitic wasps.

A nonspecific defensive compound evolves into a competition avoidance cue and a female sex pheromone.

The evolution of chemical communication and the origin of pheromones are among the most challenging issues in chemical ecology. Current theory predicts that chemical communication can arise from compounds primarily evolved for non-communicative purposes but experimental evidence showing a gradual evolution of non-informative compounds into cues and true signals is scarce. Here we report that females of the parasitic wasp Leptopilina heterotoma use the defensive compound (-)-iridomyrmecin as a semiochemical cue to avoid interference with con- and heterospecific competitors and as the main component of a species-specific sex pheromone. Although competition avoidance is mediated by (-)-iridomyrmecin alone, several structurally related minor compounds are necessary for reliable mate attraction and recognition. Our findings provide insights into the evolution of insect pheromones by demonstrating that the increasing specificity of chemical information is accompanied by an increasing complexity of the chemical messengers involved and the evolution of the chemosensory adaptations for their exploitation.