Temperature-dependent trade-offs in maternal investments: An experimental test with two closely related soil microarthropods

Organisms face trade-offs in their reproductive investment due to energetic constraints. Yet, little is known about how such investments may change at different temperatures, and particularly so in soil invertebrate organisms. Here, we studied two Collembola species (Folsomia candida and Proisotoma minuta) using a long term (several generations) temperature incubation experiment (separately at 15 and 20 ◦C) to investigate how egg size and egg numbers and the trade-off between the two are affected in two temperature regimes. Both species are known to grow at these temperatures, but the variation in their reproductive strategies are little known. Our results show that egg sizes of F. candida were larger in colder temperature whereas no such patterns were found in P. minuta. By contrast, we found no effect of the two temperatures on egg numbers (per clutch) in any of the species. Moreover, we observed a negative correlation (indication of a potential trade-off) between egg size and egg numbers (per clutch) at colder temperature in F. candida, which disappeared in warmer temperature in the same species. No such trade-offs were found in P. minuta. Our results highlight that temperature effects on maternal investments are both trait- and species-specific, particularly when Collembola species are within their optimal thermal niches

No adverse dietary effect of a cisgenic fire blight resistant apple line on the non-target arthropods Drosophila melanogaster and Folsomia candida

Genetic modification of apple cultivars through cisgenesis can introduce traits, such as disease resistance from wild relatives, quickly and without crossing. This approach was used to generate the cisgenic apple line C44.4.146, a 'Gala Galaxy' carrying the fire blight resistance gene FB_MR5. In contrast to traditionally bred apple cultivars, genetically modified (GM) plants need to undergo a regulatory risk assessment considering unintended effects before approval for commercial release. To determine potential unintended effects of C44.4.146, we assessed major leaf components and effects on the fitness of the decomposers Drosophila melanogaster (fruit fly) and Folsomia candida (collembolan), which were fed a diet amended with powdered apple leaf material. Leaf material of 'Gala Galaxy', several natural 'Gala' mutants, and the unrelated apple cultivar 'Ladina' were used for comparison. The genetic modification did not alter major leaf components and did not adversely affect survival, growth, or fecundity of the two decomposers. Consistent with previous studies with other GM crops, the differences between conventionally bred cultivars were greater than between the GM line and its non-GM wild type. These data provide a baseline for future risk assessments.ISSN:0147-6513ISSN:1090-241