Entomophaga

, Volume 21, Issue 3, pp 269–273 | Cite as

Effect of different release rates ofPhytoseiulus persimilis [Acarina: Phytoseiidae] on the twospotted spider mite on strawberry in southern California

  • E. R. Oatman
  • F. E. Gilstrap
  • V. Voth
Article

Abstract

The effect of different release rates of a predaceous mite,Phytoseiulus persimilisAthias-Henriot, on the twospotted spider mite,Tetranychus urticaeKoch, on strawberry was investigated in southern California in 1970–71. The spider mite population reached a peak of 206.3 active stages/leaflet in the low-rate (5/plant) release plot on May 4 and 169.1/leaflet in the high-rate (10/plant) release plot on May 18, compared to a peak of 433.4/leaflet in the control (no release) plot on May 11. The mean numbers of spider mites in the low-, and high-rate release plots were significantly different from the control from April 6 through June 15, but were never significantly different from each other. The predator population reached a peak of 13.1 and 23.8 active stages/leaflet in the low-, and high-rate release plots, respectively, on May 25 which was 3 weeks and 1 week after the spider mite population reached its peak in these plots. The seasonal mean numbers of spider mite active stages in the low-, and high-rate release plots were significantly different (P=0.05) from the control, but were not significantly different from each other. There were no significant differences in fruit yield (g/plant) or fruit size between the low-, and high-rate release and control plots.

Keywords

Plant Pathology Release Rate Control Plot Spider Mite Active Stage 

Résumé

Des lâchers de l'acarien prédateurPhytoseiulus persimilisAthias-Henriot ont été réalisés en 1970–71 dans deux fraiseraies de la Californie du Sud infestées parTetranychus urticaeKoch.

La densité des populations larvaires deT. urticae a atteint le 4 mai un maximum de 206,3 par foliole là où le lâcher avait été de 5 par plante (parcelle 1) et de 169,1 pour 10 prédateurs par plant (parcelle 2) le 11 mai, alors que le témoin en contenait 433,4 par foliole. La densité des populations larvaires deT. urticae était comparable dans les parcelles 1 et 2 entre le 6 avril et le 15 juin, mais divergeait sensiblement de celle du témoin. Les populations de larves du prédateur ont atteint un maximum de 13,1 et 23,8 par foliole dans les parcelles 1 et 2 les 13 et 25 mai, respectivement, soit 3 semaines et 1 semaine après que celles deT. urticae aient atteint leur maximum. Pour la saison, la densité moyenne des populations larvaires deT. urticae enregistrée dans les parcelles 1 et 2 différaient considérablement de celle du témoin (P=0.05), mais la différence entre les terrains 1 et 2 n'était pas significative.

Il n'y a pas eu de différences importantes entre la récolte de fraises (g/plante) ou la dimension des fruits récoltés dans les parcelles 1 et 2 et le témoin.

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References

  1. Oatman, E. R. &McMurtry, J. A. — 1966. Biological control of the twospotted spider mite on strawberry in southern California. —J. Econ. Entomol., 59, 433–439.Google Scholar
  2. Oatman, E. R., McMurtry, J. A. &Voth, V. — 1968. Suppression of the twospotted spider mite on strawberry with mass releases ofPhytoseiulus persimilis. —J. Econ. Entomol., 61, 1517–1521.Google Scholar
  3. Oatman, E R. &Voth, V. — 1972. Effect of flooding on the twospotted spider mite and its predators on strawberry in southern California. —Environ. Entomol., 1, 717–720.Google Scholar

Copyright information

© Le François 1976

Authors and Affiliations

  • E. R. Oatman
    • 1
  • F. E. Gilstrap
    • 2
  • V. Voth
    • 3
  1. 1.Division of Biological Control, Department of EntomologyUniversity of CaliforniaRiver-side
  2. 2.Department of EntomologyTexas A & M UniversityCollege Station
  3. 3.Department of PomologyUniversity of California, South Coast Field StationSanta Ana

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