Abstracts

Earth sciences

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Survival patterns and mortality sources of herbivorous insects: some demographic trends

Article Abstract:

A study of 530 life tables for 124 holometabolous, herbivorous insects to investigate the trends of herbivore survival, shows that myriad sources of mortality operating idiosyncratically over time and space produce distinct survival patterns among the herbivore population. Results show that exophytics have large body size and fecundity, and exhibit a higher immature mortality rate compared to endophytes. Among immature herbivores attack by natural enemies is the most frequent cause of death. Plant factors also contribute to herbivore death in the earliest stages of development.

Mortality, Observations, Insects, Herbivores

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Transcontinental crashes of insect populations?

Article Abstract:

Time-series data for 10 insect taxa in North America were examined to determine the impact of the widespread drought in the late 1980s on crashes of insect populations. Results indicated that populations were relatively high early in the decade followed by population crashes between 1987 and 1990. The crashes corresponded with the drought experienced across North America during the latter part of the decade. These suggested that extremes in weather can synchronize crashes in insect population at the continental scale.

Environmental aspects, Droughts, Insect populations

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Relations among assemblage size, host specialization, and climatic variability in North American parasitoid communities

Article Abstract:

The geographical pattern of North American parasitoid assemblages in the tropical areas is discussed. These assemblages are of idiobionts that disable their hosts during parasitization and koinobionts that permit host development after the attack. The patterns for both the idiobionts and the koinobionts do not conform with the host- or parasitoid-predation hypotheses. However, they partly support the resource-fragmentation hypothesis.

Host-parasite relationships

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