Chelicerates (scorpions, horseshoe crabs, spiders, mites and ticks) are the second largest group of arthropods and are of immense importance for fundamental and applied science. They occupy a basal phylogenetic position within the phylum Arthropoda, and are of crucial significance for understanding the evolution of various arthropod lineages. Chelicerates are vectors of human diseases, such as ticks, and major agricultural pests, such as spider mites, thus this group is also of importance for both medicine and agriculture. The developmental genetics of chelicerates is poorly understood and a challenge for the future progress for many aspects of chelicerate biology is the development of a model organism for this group. Toward this end, we are developing a chelicerate genetic model: the two-spotted spider mite Tetranychus urticae. T. urticae has the smallest genome of any arthropod determined so far (75 Mbp, 60% of the size of the Drosophila genome), undergoes rapid development and is easy to maintain in the laboratory. These features make T. urticae a promising reference organism for the economically important, poorly studied and species-rich chelicerate lineage.

Mating in the aphid parasitoid, Aphidius ervi, is mediated by sex pheromones. Virgin females produce pheromones that stimulate both upwind flight and elicit close-range courtship behavior by males. Field studies and laboratory bioassays demonstrated that time of day and adult age affect both the emission of, and receptivity to, the sex pheromones. In contrast, mating affected female pheromone production, but not male responsiveness.

Carrot rust fly (CRF), Psila rosae (Fabricius) (Diptera: Psilidae), caged with 2-month-old carrot plants at 20 °C, 50–70% RH, and 16:8 L:D laid an average of 109 eggs per female. With ca. 50% survival from egg to pupae, the rearing procedure yielded a 25 × population increase per generation. The duration of the life cycle at 20 °C was ca. 65 days. Calculated threshold temperatures and degree days above those temperatures necessary for complete development were: eggs, 4.5 °C and 94 degree days (°D); larvae, 2.02 °C and 625 °D; and pupae, 1.47 °C and 374 °D. Larvae collected in the field in fall developed normally when incubated at 22 and 19 °C; ca. 40% of the pupae entered diapause at 16 °C, and 100% at 13 and 10 °C. Fall-collected larvae chilled at 1 °C for ca. 3 months developed normally at all temperatures including those which induced diapause in pupae from unchilled larvae. With laboratory-reared pupae, 100% diapause was induced with > 10 days exposure to 13 or 10 °C. Twenty weeks storage at 1 °C was sufficient to terminate diapause in > 95% of the pupae. The ability of both CRF larvae and pupae to survive cold temperature conditions suggests that 2 separate spring emergence peaks may occur, which could have important implications if the spring flight is to be predicted on the basis of °D accumulations.

Riga, E., Whistlecraft, J. and Potter, J. 2001. Potential of controlling insect pests of corn using entomopathogenic nematodes. Can. J. Plant. Sci. 81: 783-787. A series of experiments was performed in the laboratory and in the greenhouse to assess the efficacy of the entomopathogenic nematodes, Steinernema glaseri or S. feltiae in decreasing the numbers of European corn borer, fall armyworm, western corn rootworm and the seedcorn maggot in corn. Both nematode species effectively controlled the four insect pest species. During greenhouse experiments, the number of plants protected with entomopathogenic nematodes against these insect pests was significantly higher than in the untreated controls. Similar results were obtained in a microplot study of corn infected with the European corn borer, the western corn rootworm and the seedcorn maggot. The application of a single nematode species against several insect pests has economic advantages. In addition, both S. glaseri and S. feltiae overwintered and survived in the field until the next growing season. Lors des essais en serre, la population de plants protégés par les deux espèces entomopathogènes était beaucoup plus élevée que celle des plants témoins non traités. On a obtenu des résultats similaires lors d'une étude sur une micro-parcelle de maïs infestée par la pyrale du maïs, la chrysomèle orientale des racines du maïs et la mouche des légumineuses. Le fait qu'une seule espèce de nématode combatte plusieurs ravageurs présente des avantages économiques. En outre, S. glaseri et S. feltiae survivent à l'hiver, sur le terrain, jusqu'au retour de la période végétative.

No abstract