Review of the American Corylophidae, Cryptophagidae, Tritomidae and Dermestidae, with Other StudiesBy T. L. Casey
New York Entomological Society, 1900
Journal of the New York Entomological Society, 8
(2): 51-172, 1900
Abundance of herbivores on six milkweed species in Illinois.By Price, P.W. & M.F. Willson.
American Midland Naturalist 101(1): 76–86., 1979
Price, P.W. & M.F. Willson. 1979. Abundance of herbivores on six milkweed species in Illinois. American Midland Naturalist 101(1): 76–86.
To aid the understanding of the role of insect herbivores as selective agents in the evolution of their host plants a survey of herbivore abundance and impact was undertaken in central Illinois on the six milkweed species: Asclepias incarnata, A. sullivantii, A. syriaca, A. verticillata, A. amplexicaulis
, and A. tuberosa
. These species occur in this order on a moisture gradient from wet to dry soil conditions. This survey revealed that 12 species occurred at an abundance of at least one individual per 100 host stems in 1 plot-year on one host species: Oncopeltus fasciatus*, Lygaeus kalmii*, Aphis nerii*, Labidomera clivicollis*, Tetraopes tetrophthalmus*, T. femoratus, T. quinquemaculatus, Rhyssomatus lineaticollis*, Danaus plexippus, Cycnia tenera*, Euchaetias egle
and a leafminer. All but L. kalmii
are specific to milkweeds in Illinois. Seven of these species, marked with asterisks, were abundant enough to act as major selective forces on the life history patterns of the milkweed species, populations and clones concerned.
Life history evolution in seven milkweeds of the genus Asclepias.By Wilbur, H.M.
The Journal of Ecology, 64(1): 223–240., 1976
Wilbur, H.M. 1976. Life history evolution in seven milkweeds of the genus Asclepias
. The Journal of Ecology, 64(1): 223–240.
Life history differences among seven species of Asclepias
(A. exaltata, A. incarnata, A. purpurascens, A. syriaca, A. tuberosa, A. verticillata
and A. viridiflora
) in south-east Michigan are correlated with differences in microhabitat, in exposure to herbivores, and in competition. Components of each species' reproductive strategy include: number of stems per plants, number of umbels per stem, number of flowers and pods per umbel, number of seeds per pod, seed weight and annual increase in reproductive potential. Components of each species' selective regime include: the herbivore load (measured by the frequency of plants damaged by predators or animal parasites), competition (measured by the proportion of non-flowering plants and by the density of competitors), and environmental uncertainty (measured by annual mortality rates).