Iacomo Jonasson posted an update 1 week, 3 days ago
Tissues were dried at 65?��C for 48?h and weighed. Specific stem length (SSL; the ratio of main stem length to its weight; in cm/g) was calculated. The diameter (d) of the main stem from each morph was measured with calipers at the midpoints of the internodes between the third and fourth fully expanded leaf pairs. The mean tissue density (��) of the main stem was determined from the ratio of stem weight to volume, the latter being determined by submerging a stem in distilled water and recording the volume of Vorinostat cell line displaced water. In the case of alligator weed with hollow internodes, stems were cut into median longitudinal sections before being submerged in water. There are two major sources of variability in this experiment, the first arising from the collection of ramet material and the second from differences among the six morphs. We used analysis of variance (ANOVA) and Fisher’s least significant difference (LSD) test to determine whether plants in the six morphs differed in terms of morphological and growth traits. Coefficients of variation (CV) were calculated. We used a cylinder model (with a uniform cross-sectional geometry) to examine correlations between SSL and the two stem traits, namely tissue density (��) and stem diameter (d): We used preference hierarchy (feeding and oviposition) of flea beetles feeding on different morphs of alligator weed as the measure of herbivory hierarchy. The preference hierarchy of A. hygrophila was determined by multiple-choice experiments (15 replicates). This type of experimentation gives the same results as binary and no-choice experiments (Fu et al., 2007), and is therefore considered to give reliable estimates of host preference. One pot of each morph was offered simultaneously to five female adults during a trial. All plants in the trial were of the same age (5 weeks), with leaf biomass sufficient to rear the beetles. Pots were randomly positioned in a flight cage (50?��?75?��?75?cm). We observed beetles moving freely among the six morph pots. The cages were kept at 25?��?2?��C and relative humidity of 75%�C90% under a 14:10?h light�Cdark period. Each trial lasted for 72?h, after which the number of eggs and leaf area consumed per genotype were recorded. We converted the leaf area consumed to leaf dry mass using the specific leaf area, leaf area/leaf dry mass (SLA) of each alligator weed morph. We then estimated the herbivory intensity of flea beetles on the six morphs using the number of eggs and the leaf mass consumed per day. To test the prediction that stem diameter and tissue density of different morphs of alligator weed can affect the pupation rate of flea beetle (five replicates), the pupation rates on six genotypes were determined by raising the eggs under a no-choice experiment. Larvae were drawn at random from eggs that were laid by multiple females on each morph. Ten first instar larvae (<24?h old) were placed gently on apical leaves using a paintbrush.