Megachile rotundata (F.), a gregarious, cavity-nesting, leaf-cutting bee, is used throughoutNorthAmerica for the pollination of alfalfa,Medicago sativaL., seed crops.We examined the inßuence of various temperature regimes on development, survival, emergence, and longevity in both nondiapausing and diapausing forms of this species. In general, development rates increased with increasing constant...

Taking an experimental approach to paleoecology, we evaluated the prey portion of Van Valen’s Red Queen hypothesis by retrieving diapausing eggs from lake sediments for laboratory tests of evolutionary responses. The sediments consisted of core samples from Portage Lake (Michigan), which were dated by a combination of varve counts and radioisotope (137Cs and 210Pb) techniques. The sedimentary r...

Perhaps more intriguing, when inedible algae were absent, only some of the experimental cultures displayed predator–prey cycles of high amplitude. Others cycled with lower amplitude, and with phasing of adults and juveniles suggesting demographic cycles. This result demonstrates ‘alternative attractors’ — that is, two dynamical states that characterize the long-term behaviour of Daphnia populat...

Climate differences across latitude can result in seasonal constraints and selection on life-history characters. Because Aedes albopictus (Skuse) invaded North America in the mid-1980s, it has spread across a range of ≈14° latitude and populations in the north experience complete adult mortality because of cold winter temperatures that are absent in the south. Life-table experiments were conduc...

The codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), a worldwide apple pest, is classified as a freeze-intolerant organism and one of the most cold-tolerant pests. The objectives of this study were to examine the supercooling point of overwintering and non-diapausing larvae of C. pomonella as an index of its cold hardiness, and to assess larval mortality following 24 h exposure to e...

Forty percent of the world's population is at risk of contracting dengue virus, which produces dengue fever with a potentially fatal hemorrhagic form. The wMelPop Wolbachia infection of Drosophila melanogaster reduces life span and interferes with viral transmission when introduced into the mosquito Aedes aegypti, the primary vector of dengue virus. Wolbachia has been proposed as an agent for p...

The life cycles of two plant species in the Mediterranean chaparral, the evergreen Arbutus andrachne and the deciduous Rhamnus lycioides, were studied, as were the cycles of two stenophagous whitefly species that live on them, Trialeurodes lauri and Dialeurolobus rhamni, respectively. Trialeurodes lauri is univoltine, diapausing from June to March corresponding to the plant’s leaf dormancy. The...

1 In the present study, we documented the lethal and sublethal effects of the entomopathogen Btk on spruce budworm and its progeny under various environmental conditions. We hypothesized that aerial spray of Bacillus thuringiensis ssp. kurstaki (Btk) could affect the biological performance of the surviving spruce budworm (Choristoneura fumiferana Clem.) populations and their progenies and that ...