A Unified Approach to Analysis of Body Condition in Green Toads.

Body condition is increasingly used to assess the status of populations and as a proxy for individual fitness. A common, quick and non-invasive approach is to estimate condition from the relation between body length and mass. Among the methods developed for this purpose, the Scaled Mass Index (SMI) appears best suited for comparisons among populations. We assembled data from 17 populations of European green toads (Bufotes viridis) with the aim of devising a standard formula applicable for monitoring this species. The mean value of the exponents describing length-mass allometry in these samples was 3.0047. Hence, we propose using 3 as a scaling coefficient for calculating the SMI in green toads. From the contrast of SMI values for both sexes within populations, estimated with either the population-specific or the standard coefficient, we conclude that applying the standard formula not only facilitates comparisons among populations but may also help to avoid misinterpretation of variation within populations.

Effects of insect cuticular fatty acids on in vitro growth and pathogenicity of the entomopathogenic fungus Conidiobolus coronatus.

Eighteen fatty acids identified in the cuticle of three insect species representing differing susceptibilities to C. coronatus infection, were tested for effects on the in vitro growth and pathogenicity of the parasitic fungus. At all applied concentrations (0.1-0.0001% w/v) growth was inhibited by C(16:0), C(16:1), C(18:0), C(18:1), C(18:2), C(18:3), C(20:0) and C(20:1). At high concentrations spore germination was inhibited by C(7:0), C(8:0), C(9:0), C(10:0), C(12:0), C(18:2) and C(18:3) and hyphal growth was merely retarded by C(5:0), C(6:0), C(6:2), C(14:0), C(16:0), C(16:1), C(18:0,) C(18:1), C(20:0) and C(20:1). The presence of C(15:0) at the 0.1% concentration stimulated growth of C. coronatus. Sporulation was inhibited by all concentrations of C(16:0) and C(18-20) fatty acids. Low concentrations of C(5:0), C(6:0), C(6:2) and C(7:0) enhanced sporulation. Fatty acids C(5-12) as well as C(18:3), C(20:0) and C(20:1) decreased the ability of fungal colonies to infect G. mellonella while C(16:1) elevated it thus suggesting that C(16:1) may stimulate production of enzymes involved in the host invasion. Toxicity of metabolites released into incubation medium decreased with varying degrees in the presence of C(6:0), C(6:2,) C(7:0), C(9:0), C(12:0), C(16:1), C(18:2), C(18:3), C(20:0) and C(20:1); other fatty acids had no effect. Further work is needed to analyse the effects of exogenous fatty acids on the C. coronatus enzymes implicated in fungal pathogenicity as well as on the production of insecticidal metabolites.