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.
Can exotic phytoseiids be considered ‘benevolent invaders’ in perennial cropping systems?
Numerous natural enemies were adopted worldwide for the control of major pests, including exotic phytoseiid species (Acari: Mesostigmata: Phytoseiidae) that had been moved from continent to continent in protected and perennial agricultural systems. However, relatively fewer successes were recorded in perennial agricultural systems. In this manuscript we focus on the question: Can and will exotic phytoseiids provide better pest control than indigenous species in perennial agricultural systems? To answer this question, we review the efficacy of biological control efforts with phytoseiids in several case studies, where exotic and indigenous species were used against pests on indigenous host plants and some crops that were historically or recently introduced. Related factors affecting predator establishment, such as intraguild predation and pesticide effects are discussed, as well as the potential negative effects of exotic species releases on biological control and their impact on the indigenous natural fauna. On citrus, apple, grape and cassava exotic phytoseiids have enhanced biological control without negatively affecting indigenous species of natural enemies, except for the case of Euseius stipulatus (Athias-Henriot) on citrus that displaced Euseius hibisci (Chant) in a limited region of coastal California, USA, the latter considered to be an inferior biocontrol agent of Panonychus citri Koch. Phytoseiulus persimilis Athias-Henriot on gorse, an invasive weed, is perhaps the only recorded case of a negative effect of an established exotic phytoseiid on biological control.
The Role of Predators and Other Biotic Agents in Regulating the Population Density of Phytophagous Mites in Ontario Peach Orchards
Abstract More than 40 species of insects and arachnids attack Panonychus ulmi (Koch), Tetranychus urticae Koch, T. canadensis (McGregor), Bryobia arborea Morgan and Anderson, or Aculus cornutus (Banks) in peach orchards of the Niagara Peninsula. The most effective predators attacking P. ulmi are Typhlodromus caudiglans Schuster, Haplothrips faurei Hood, Stethorus punctillum Weise, and Chrysopa spp. Peach orchards lack the predatory mirids characteristic of apple orchards. A condition, presumably disease, caused heavy mortality in one year. Endemic densities of P. ulmi are maintained in that state by predators, chiefly T. caudiglans, that subsist to a considerable extent on other sources of food, whereas epidemics of P. ulmi are reduced largely by other predators, chiefly H. faurei and S. punctillum, that increase in numbers by feeding on the mite during its period of rapid population growth but exert their greatest effect later in the season by destroying the winter eggs.