Location, reproduction and movement of Neoseiulus californicus (Acari: Phytoseiidae) during the autumn, winter and spring in orchards in the south of France
Field samples and experiments conducted in apple orchards in the south of France showed that Neoseiulus californicus (McGregor) searched for prey on the trees and in the ground cover as late as mid-November 1993, and at least as early in the spring as the end of February 1994. Overwintering females fed, expanded and produced viable eggs within 7.9±0.3 (SE) days given the natural light regime, adequate food and temperatures of 17.0±20.6°C. The first generation of N. californicus developed in the field during March and April 1994. N. californicus nymphs, females and males readily moved over bare ground and through a grass ground cover to trap plants located on stakes 1 m above the ground. In the laboratory, the rate of movement of adult females on 0.5 mm copper wire was a linear function of temperature above a threshold of 11.9±0.9°C. At 25°C they travelled 10 m per h. The migration rate of N. californicus to trap plants on stakes placed in an orchard 13 Apr. increased in 2 weeks from 0.07 to 0.57 predators/trap plant/degree-day, while the migration rate to plants placed directly in the ground cover was 1.45 predators/trap plant/degree-day. The largest population of N. californicus in April occurred on Barley, Hordeum murinum L. This plant produces pollen in April and May, and may be useful in biocontrol programs.
Predatory behaviors of Neoseiulus californicus and Galendromus helveolus (Acari: Phytoseiidae) attacking Oligonychus perseae (Acari: Tetranychidae)
Predatory behaviors of Neoseiulus californicus (McGregor) and Galendromus helveolus (Chant) attacking Oligonychus perseae Tuttle, Baker and Abbatiello on avocado leaves were videotaped and analyzed. Behaviors were recorded for “fresh” predators that were used ≤ 48 hr post receipt from a commercial insectary and “cold stored” predators that were maintained at 12°C for ≈ 14 days. Fresh and cold stored G. helveolus were observed to attack O. perseae only after invading webbed nests. Conversely, fresh and cold stored N. californicus employed three different modes of predatory attack: (1) intercepting and attacking migrant O. perseae outside of web nests; (2) attacking prey through nest webbing; or (3) invading and attacking O. perseae inside nests. Predatory efficacy of both N. californicus and G. helveolus was reduced following cold storage, as both species engaged in certain predatory behaviors less frequently in comparison to predators that were not stored at low temperatures. Our observed results for N. californicus and G. helveolus attacking O. perseae are interpreted in relation to the chaetotaxy hypothesis, which proposes that phytoseiid invasion efficiency and propensity of webbed nests is facilitated by dorsal setal lengths.
Some ecological roots of pest control
Development of pest management systems rests on relatively few major ecological principles and these underly the tactics and strategies available. Many are so self-evident that we often ignore their underlying significance. They are (1) the principle of inherent variation in the genetic properties of organisms; (2) the principle that an organism must be adapted to its environment and becomes so through its evolution; (3) the principle that all organisms require adequate nutrition; (4) the principle that to perpetuate their kind organisms must reproduce; (5) the principle that as organisms are born immature they must grow and develop; (6) the principle that life presents various compensations tending to correct for adverse occurrences; (7) the principle that most organisms derive their sustenance from other living organisms (predation); (8) the principle that organisms commonly suffer from depletion of resources by other organisms (competition among the same or different kinds of organisms); (9) the principle that cooperation serves many species well; (10) the principle that organisms must move about and do things (possess mobility and other behavior); and (11) the principle of holism and interactions among factors in ecosystems. Examples are given showing that advances in our knowledge in each of these basic areas are significant in developing ecologically sound pest management systems.RésuméDans cet article nous donnons des exemples montrant que contre des insectes nuisibles, toute lutte écologiquement satisfaisante est fondée sur nos progrès dans la connaissance de onze principes fondamentaux d'écologie. Nous discutons les principes concernant la variation génétique, l'adaptation, la nutrition, la reproduction, la croissance et le développement, la compensation vis-à-vis de facteurs adverses, la prédation (y inclus le parasitisme), la compétition, la coopération, la mobilité et les interactions de facteurs dans un système global.