Climate and weather influences on spatial temporal patterns of mountain pine beetle populations in Washington and Oregon.

Widespread outbreaks of mountain pine beetle in North America have drawn the attention of scientists, forest managers, and the public. There is strong evidence that climate change has contributed to the extent and severity of recent outbreaks. Scientists are interested in quantifying relationships between bark beetle population dynamics and trends in climate.

Historical demography and phylogeography of a specialist bark beetle, Dendroctonus pseudotsugae Hopkins (Curculionidae: Scolytinae).

Contemporary distribution of North American species has been shaped by past glaciation events during the Quaternary period. However, their effects were not as severe in the southern Rocky Mountains and Northern Mexico as elsewhere in North America. In this context, we test hypotheses about the historical demography of Dendroctonus pseudotsugae, based on 136 haplotypes of mitochondrial cytochrome oxidase I.

Effect of geographic isolation on genetic differentiation in Dendroctonus pseudotsugae (Coleoptera: Curculionidae).

Genetic structure of phytophagous insects has been widely studied, however, relative influence of the effect of geographic isolation, the host plant or both has been subject of considerable debate. Several studies carried out on bark beetles in the genus Dendroctonus evaluated these factors; nonetheless, recent evidence has shown that genetic structuring is a more complex process. Our goal was to examine the effect of geographic isolation on genetic structure of the Douglas-fir beetle Dendroctonus pseudotsugae.

Phylogeography of the bark beetle Dendroctonus mexicanus Hopkins (Coleoptera: Curculionidae: Scolytinae).

Dendroctonus mexicanus is polyphagous within the Pinus genus and has a wide geographical distribution in Mexico and Guatemala. We examined the pattern of genetic variation across the range of this species to explore its demographic history and its phylogeographic pattern. Analysis of the mtDNA sequences of 173 individuals from 25 Mexican populations allowed to us identify 53 geographically structured haplotypes.

Egg distribution and survivorship in the pierid butterfly, Colias alexandra.

Patterns of egg distribution and survivorship were examined for six generations (1975-79 and 1981) of a univoltine population of the pierid butterfly Colias alexandra. Unlike some other of the so-called red-egged pierids, there is no evidence of egg-recognition in this Coliadine species. Two distribution patterns were observed: contagious or clumped in 1976-1979, but random in 1981.

Diapause and diapause dynamics of Colias alexandra (Lepidoptera: Pieridae).

The mechanisms and adaptations involved in the "obligate" third instar larval diapause of Colias alexandra, a native Rocky Mountain and intermountain region butterfly, are examined. Generally univoltine throughout its distribution, scattered, isolated bivoltine populations occur. Factors influencing continuous development were investigated under laboratory conditions on a single generation of offspring from a univoltine population each year from 1976-1979.