Population Dynamics of Chewing Lice (Phthiraptera) Infesting Birds (Aves).

In the past 25 years, studies on interactions between chewing lice and their bird hosts have increased notably. This body of work reveals that sampling of live avian hosts, collection of the lice, and the aggregated distributions of louse infestations pose challenges for assessing louse populations. The number of lice on a bird varies among host taxa, often with host size and social system.

Interactions between exotic and native lady beetle species stabilize community abundance.

A 23-year time-series of abundance for 13 lady beetle species (Coccinellidae) was used to investigate community stability. The community exhibited persistence in ten habitats, no overall trend in abundance, and low temporal variability quantified as Population variability (PV) = 0.33 on a scale from 0 to 1 that declined to 0.

Variability in life history traits of the aphid, Acyrthosiphon pisum (Harris), from sexual and asexual populations.

Many aphid species have shown remarkable adaptability by invading new habitats and agricultural crops, although they are parthenogenetic and might be expected to show limited genetic variation. To determine if the mode of reproduction limits the level of genetic variation in adaptively important traits, we assess variation in 15 life history traits of the pea aphid, Acyrhosiphon pisum (Harris), for five populations sampled along a north-south transect in central North America, and for three traits for three populations from eastern Australia. The traits are developmental times and rates as affected by temperature, body weights as affected by temperature, fecundity, measures of migratory tendency, and photoperiodic responses.

Effects of temperature on the development, growth, and survival of larvae and pupae of a north-temperate chrysomelid beetle.

Developoment, growth, and survival of larvae and pupae of the red turnip beetle, Entomoscelis americana Brown, were studied in 10 constant and four alternating temperature regimes (10 to 32.5° C), in field-cages, and in natural populations in Manitoba. This beetle has a northtemperate distribution in North America.

Migratory tendency in aging populations of the pea aphid, Acyrthosiphon pisum.

Sweep samples of the aphid, Acyrthosiphon pisum, were collected from six natural populations ranging in age from one to five years. Clones were established in the laboratory from the field-collected adults and tested for their migratory tendency in two subsequent generations by measuring the percentage of winged offspring produced in response to a standard stimulus. The number of aphids in sweep samples and the percentage of winged and wingless aphids were also determined.

Variability in migratory tendency within and among natural populations of the pea aphid, Acyrthosiphon pisum.

The migratory tendencies of pea aphids were measured by determining the numbers of winged and non-winged offspring produced by parthenogenetic wingless females after a crowding test. Sources of variability in this measure were investigated. The migratory tendency of an individual clone was found to be stable.