SUMMARYChanges in animal behavior resulting from genetic or chemical intervention are frequently used for phenotype characterizations. The majority of these studies are qualitative in nature, especially in systems that go beyond the classical model organisms. Here, we introduce a quantitative method to characterize behavior in the freshwater planarian Schmidtea mediterranea. Wild-type locomotion in confinement was quantified using a wide set of parameters, and the influences of intrinsic intra-worm versus interworm variability on our measurements was studied. We also examined the effect of substrate, confinement geometry and the interactions with the boundary on planarian behavior. The method is based on a simple experimental setup, using automated center-of-mass tracking and image analysis, making it an easily implemented alternative to current methods for screening planarian locomotion phenotypes. As a proof of principle, two drug-induced behavioral phenotypes were generated to show the capacity of this method. Supplementary material available online at

Asexual reproduction in multicellular organisms is a complex biophysical process that is not yet well understood quantitatively. Here, we report a detailed population study for the asexual freshwater planarian Schmidtea mediterranea, which can reproduce via transverse fission due to a large stem cell contingent. Our long-term observations of isolated non-interacting planarian populations reveal that the characteristic fission waiting time distributions for head and tail fragments differ significantly from each other. The stochastic fission dynamics of tail fragments exhibits non-negligible memory effects, implying that an accurate mathematical description of future data should be based on non-Markovian tree models. By comparing the effective growth of non-interacting planarian populations with those of self-interacting populations, we are able to quantify the influence of interactions between flatworms and physical conditions on the population growth. A surprising result is the non-monotonic relationship between effective population growth rate and nutrient supply: planarians exhibit a tendency to become 'obese' if the feeding frequency exceeds a critical level, resulting in a decreased reproduction activity. This suggests that these flatworms, which possess many genes homologous to those of humans, could become a new model system for studying dietary effects on reproduction and regeneration in multicellular organisms.

The intrinsic rates of increase (rm) of Cyrtobagous salviniae Calder & Sands from Brazil and C. singularis H ustache from Trinidad W.I., were determined in the laboratory at 23 °C, 27 °C and 31 °C on nitrogen‐rich plants of the aquatic weed, Salvinia molesta Mitchell. Variation in oviposition and immature survivorship accounted for most of the differences between species in rm values (exponential growth of a stable‐age population in a non‐limiting environment). Values for rm were higher for C. salviniae (0.210, 0.366, 0.404) than for C. singularis (0.148, 0.140, 0.064) at the three temperatures respectively. At all temperatures, C. salviniae laid seven times more eggs than C. singularis while at 31 °C oviposition was reduced for both species by 45%, and was accompanied by a reduction in egg hatch. Oviposition by C. salviniae was almost continuous (92% of weeks with some eggs laid) whereas oviposition by C. singularis was intermittent (50% of weeks) with intervals averaging 2 weeks without oviposition. Nitrogen concentration in S. molesta affected reproduction by C. singularis more than C. salviniae, an increase of 0.1% (dry wt) increasing weekly oviposition by 7.0% and 3.6% respectively. The differences in rm for the two weevil species are discussed in relationship to their potential as biological control agents. Résumé Taux intrinsèques d'accroissement de Cyrtobagous singularis Hustache and C. salviniae Calder & Sands, utilisés dans la lutte biologique contre Salvinia molesta Mitchell Les taux intrinsèques d'accroissement (rm) de C. salviniae du Bresil et de C. singularis de Trinidad, ont été établis au laboratoire à 23 °C; 27 °C; 31 °C, sur des plants de S. molesta riches en azote. Les différences entre les rm des deux espèces provenaient pour l'essentiel de la ponte et de la mortalité préimaginale. Aux 3 températures, les valeurs de rm de C. salviniae (0.210; 0.366; 0.404) étaient supérieures à celles de C. singularis (0.148; 0.140; 0.064). A toutes les températures C. salviniae a pondu 7 fois plus d'oeufs que C singularis, à 31 °C, la ponte a été réduite de 45% pour les 2 espèces et été accompagnée d'une diminution des taux d'éclosion. La ponte de C. salvinae était presque continue (92% des semaines avec des oeufs), tandis que celle de C. singularis était intermittente (50% des semaines avec pontes), les interruptions étant en moyenne de 2 semaines. La teneur de S. molesta en azote a affecté la reproduction de C. singularis plus que celle de C. salviniae; un accroissement de 0.1% en poids sec, augmentant les pontes hebdomadaires respectivement de 7% et de 3.6%. Les différences de valeur de rm des 2 espèces sont examinées pour évaluer leurs potentialités comme éléments de la lutte biologique.

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SUMMARYWe have developed a 'Scan-Add-Print' database system, SAPling, to track and monitor asexually reproducing organisms. Using barcodes to uniquely identify each animal, we can record information on the life of the individual in a computerized database containing its entire family tree. SAPling has enabled us to carry out large-scale population dynamics experiments with thousands of planarians and keep track of each individual. The database stores information such as family connections, birth date, division date and generation. We show that SAPling can be easily adapted to other asexually reproducing organisms and has a strong potential for use in large-scale and/or long-term population and senescence studies as well as studies of clonal diversity. The software is platform-independent, designed for reliability and ease of use, and provided open source from our webpage to allow project-specific customization.Supplementary material available online at

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