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Studies on integrating Phyloseiulus persimilis Athias-Henriot releases, chemical applications, cultural manipulations, and natural predation for control of the two-spotted spider mite, Tetranychus urticae (Koch), on strawberry were conducted in southern California during 1965–66. Treatments consisted of a pre-planting furrow application and a post-planting sidedress application of phorate granules, foliage spray application of binapacryl, and 2 nonpesticide checks in one of which sanitation (nonfunctioning senescent leaves removed from field) was practiced. Treatment plots were established in a randomized complete block design and replicated 4 times. Mass releases of P. persimilis were made on ½ of each plot at weekly intervals during March at the equivalent rate of 384,000 per acre total for the period. Populations of prey and predators were sampled at weekly intervals throughout the study. In the check plot, the spider mite population declined from an average of 13.1 mites per leaflet on September 28, 1965 (5 weeks after transplants were planted) to a low of 1.0 per leaflet on January 4, 1966, reached a peak of 162.7 on March 15, after which it declined to an average of less than 1.0 per leaflet by May 17, remaining below 0.5 per leaflet through the end of the study on June 28. Reduction of the spider mite population in the check was due primarily to the combined action of 8 predators, of which the six-spotted thrips, Scolothrips sexmaculatus (Pergande), was the dominant species. Removal of the non functioning leaves resulted in an overall 55.4% reduction in the spider mite population, with a corresponding reduction in total predator numbers during a 6-week period subsequent to their removal. Because of the unusually early increase in and the high population reached by the two-spotted spider mite, plant damage was not prevented by P. persimilis releases although the pest population was reduced by an overall average of 18.9%. P. persimilis reached its peak population 6-8 weeks after initial releases, averaging up to 4.6 actives per leaflet and occupying 75-100% of the leaflets sampled. Mass releases of P. persimilis had no adverse effect on natural predation, Strawberry yield was increased by an overall average of 18.1% where P. persimilis was released. Good initial spider mite control was obtained with the phorate treatments. However, they were no longer effective by the time the P. persimilis releases were made in March. Suppression of the spider mite in the binapacryl plots was followed by even higher populations, indicating an indirect adverse effect of chemical control and emphasizing the desirability of developing an effective integrated control program.

The population dynamics of mite species on apple foliage was studied in a natural (unsprayed check) and 2 artificial (captan and DDT-captan) environmental blocks established in a mature ‘Northwestern Greening’ apple orchard in Door County, Wisconsin, from 1959 through 1962. The phytophagous species, including Panonychus ulmi (Koch), Eotetranychus uncatus Garman, Bryobia arborea Morgan & Anderson, and Aculus schlechtendali (Nalepa), reached their highest numbers each year in the DDT-captan block except for B. arborea which was highest in the check block in 1959. The population of each species was lowest each year in the check block. The predaceous phytoseiid mites reached their highest numbers in the check block in 1959, check and captan block in 1960, and captan block in 1961 and 1962. Their populations were annually lowest in the DDT-captan block, indicating a generally adverse effect by DDT. The population of the predaceous mite Agistemus fleschneri Summers was similar in each environmental block in 1959 but reached its highest peaks and seasonal averages in the DDT-captan block each year thereafter. Two fungusfeeding species, Tarsonemus setifer Ewing and Calvolia sp., reached their highest numbers in the captan block in 1959 and in the check block each year thereafter. The higher populations of the phytophagous species in the DDT-captan block were attributed to the more luxuriant foliage, resulting from control of apple scab, Venturia inequalis (Winters), by captan; lower phytoseiid mite populations; and a stimulative effect apparently induced by physiological changes in the host trees by DDT. Nine species of phytoseiids were present with Typhlodromus caudiglans Schuster and T. fallacis (Garman) being the most common in the check and DDT-captan blocks, respectively. The high numbers of T. fallacis and A. fleschneri in the DDT-captan block indicate that they are tolerant to DDT. The low numbers of T. setifer and Calvolia sp. in the captan and DDT-captan blocks were attributed primarily to the reduction of apple scab by captan. The data further indicate that an apple orchard is an exceeding complex agro-ecosystem which is easily disrupted by pesticide applications.

A 4-year study of the naturally occurring biotic control factors affecting the eye-spotted bud moth, Spilonota ocellana (Denis and Schiffermuller), on apple in Wisconsin revealed the existence of parasitic, predatory, and microorganismal agents. Nine hymenopterous parasites, three predators, and four pathogens were involved. Principal parasitic species were Itoplectis conquisitor (Say) and Habrocytus phycidis Ashmead. Aspergillus flavus Link and a polyhedral virus were the most prevalent causes of disease. A high mortality occurring in the pupal stage could not be attributed to known causes. It is postulated that the comparatively low numbers of primary species and their small part in the regulation of the eye-spotted bud moth population may have been due mainly to the extensive use of pesticides in the area. The need for the use of selective pesticides in an integrated control program is emphasized.