Geology topics

M.W. Nelson

Publications and source records attributed to M.W. Nelson.

2 recordsLinked to original sources

USGS2007

Larval feeding behavior and ant association in frosted elfin, Callophrys irus (Lycaenidae)

Callophrys irus is a rare and declining lycaenid found in the eastern U.S., inhabiting xeric and open habitats maintained by disturbance. Populations are localized and monophagous. We document a previously undescribed larval feeding behavior in both field and lab reared larvae in which late instar larvae girdled the main stem of the host plant. Girdled stems provide a unique feeding sign that was useful in detecting the presence of larvae in the field. We also observed frequent association of field larvae with several species of ants and provide a list of ant species. We suggest two hypotheses on the potential benefits of stem-girdling to C. irus larvae: 1) Stem girdling provides phloem sap as a larval food source and increases the leaf nutrient concentration, increasing larval growth rates and providing high quality honeydew for attending ants; 2) Stem girdling reduces stem toxicity by inhibiting transport of toxins from roots to the stem.

Journal of the Lepidopterists' Society↗

USGS1981

Decline and present status of breeding Peregrine Falcons in Oregon

Unprecedented declines of the Peregrine Falcon ( Falco peregrinus ) throughout much of the Northern Hemisphere became apparent during the Madison Peregrine Falcon Conference in 1965 (Hickey 1969). Data from Britain were the most detailed; broken or missing eggs were much more common in 1949-56 than they had been in earlier years (Ratcliffe 1958). Subsequently, Ratcliffe (1967) showed a significant decrease in eggshell weight of peregrines in Britain starting in 1947 or 1948. Later, the same finding was demonstrated in North America (Hickey and Anderson 1968). The relation of eggshell thickness to DDE residue levels was established for Alaskan peregrines by Cade et al. (1971) and Peakall et al. (1975). Peakall (1976) stated that pesticides were considered to be a major factor in the decline of the peregrine, and tentatively concluded that the level of DDE in eggs that failed to hatch was 15-20 ppm (wet weight.)

Oregon↗