Differential herbivory in an oak population: the role of plant phenology and insect performance

• Published in: Ecology (Durham) 1995-06, Vol.76 (4), p.1233-1241
• Main Authors: Mopper, Susan, Simberloff, Daniel
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; BIOMASA; BIOMASS; BIOMASSE; COSMOPTERIGIDAE; DENSIDAD DE LA POBLACION; DENSITE DE POPULATION; DIMENSION; DIMENSIONS; Environmental aspects; FENOLOGIA; FENOTIPOS; FEUILLE; FLORIDA; FLORIDE; FOOD PLANTS; Fundamental and applied biological sciences. Psychology; Herbivores; HOJAS; HOSTS; HOTE; HUESPEDES; INFESTACION; INFESTATION; Insect ecology; Insect larvae; LARGURA; LEAF AREA; Leafminers; LEAVES; LENGTH; Lepidoptera; LONGUEUR; Mining; MORTALIDAD; MORTALITE; MORTALITY; Oak; PHENOLOGIE; PHENOLOGY; PHENOTYPE; PHENOTYPES; Phytopathology. Animal pests. Plant and forest protection; Phytophagous insects; Plant populations; POPULATION DENSITY; Protozoa. Invertebrates; QUERCUS; Quercus geminata; Records, symptoms, damages, economic importance, population surveys; SIZE; STEMS; stilbosis quadricusta; SUPERFICIE FOLIAR; SURFACE FOLIAIRE; TALLO; TIGE; Trees
• ISSN: 0012-9658; 1939-9170
• DOI: 10.2307/1940930

Individual trees in a North Florida population of Quercus geminata, (sand live oak) vary widely in rates of herbivory by a leaf-mining moth (Stilbosis quadricustatella). Some oaks are always heavily infested while neighboring trees remain lightly attacked. We conduct field experiments in 1991 and 1992 to determine if leafminer performance on heavily and lightly attacked trees contributed to this pattern. We also compared the leaf production phenology, leaf area, and stem length of heavily and lightly attacked trees to determine if tree phenotypic traits influenced herbivory. Our results indicate that: (1) Light attacked trees produced leaves earlier in the spring than heavily attacked trees, and the difference among trees in leaf production phenology explained 61% of the variation in leafminer densities (P = 0.008). (2) Lightly attacked trees produced significantly smaller leaves than heavily attacked trees, but leaf size explained only 13% of the variation in herbivory (P = 0.048). (3) There were no differences in larval performance on heavily and lightly attacked trees in either 1991 or 1992, with the exception of egg mortality, which was significantly higher on lightly attacked trees in 1991 (P = 0.04). (4) Host plants caused greater leafminer mortality than natural enemies, but neither differed significantly between heavily and lightly attacked trees. Our transfer experiments and observations of wild leafminers revealed little difference in leafminer performance on heavily and lightly attacked Quercus geminata trees. However, tree phenotypic traits differed, especially the timing of spring foliation, which occurred significantly earlier among trees with low rates of herbivory. These results suggest that leafminer ovipositional preference, rather than performance, could be an important determinant of differential herbivory. There may be an unknown selective advantage to preferential oviposition on trees with delayed spring leaf production.