Overwintering sites of the predacious mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) in satsuma mandarin orchards on Jeju Island, Korea

Abstract

We investigated the overwintering sites of the predacious mite Neoseiulus californicus in two satsuma mandarin orchards on Jeju Island, Korea, in February 2008. Our objectives were to improve the biological control strategy with N. californicus in perennial crops and to develop effective methods for examining the overwintering situations of N. californicus in the field. Nearly all specimens of N. californicus collected in the orchards were adult females, and the numbers of adult males and juveniles were very low. Most N. californicus were collected on herbaceous plants on the ground rather than on satsuma mandarin trees or woody plants surrounding the orchards. Among herbaceous plant species, higher densities of N. californicus were consistently found on species with rosette-type leaves compared to those with non-rosette-type leaves. Our results suggest that rosette-forming herbaceous plants are effective overwintering sites for conserving N. californicus in orchards. Furthermore, these plants would also provide useful sites for examining the potential overwintering situations of N. californicus in the field.

Effects of sheltered ground habitats on the overwintering potential of the predacious mite Neoseiulus californicus (Acari: Phytoseiidae) in apple orchards on mainland Korea

“…Kawashima and Jung (2010b) found consistently higher densities of N. californicus on rosette-forming weeds than on non-rosette-forming herbaceous weeds in satsuma mandarin orchards on Jeju Island. Since rosette-forming weeds provide more sheltered structures (e.g., between broad leaves, between the leaves and the ground, and inside dense leafstalks) than non-rosette-forming weeds, rosette-forming weeds may have similar effects to our urethane foam as sheltered ground habitats.…”

“…These studies suggest that in the field, N. californicus prefers to overwinter on the ground. Furthermore, Kawashima and Jung (2010b) found relatively more N. californicus individuals on herbaceous weeds with rosette leaves than on plants with non-rosette leaves. Since rosette-forming weeds provide more sheltered structures (e.g., between broad leaves, between the leaves and the ground, and inside dense leafstalks) than non-rosette-forming weeds, they suggested that sheltered ground habitats would be beneficial as overwintering sites.…”

“…We did not remove weeds growing in the study orchard, but we avoided using locations where rosette-forming weeds were growing, since there was a possibility that these weeds would provide better overwintering sites for N. californicus (Kawashima and Jung 2010b).…”

“…To supplement predation by this species, commercialization of the Jeju Island strain of N. californicus is currently being considered, especially for mainland apple orchards. Kawashima and Jung (2010b) investigated overwintering sites of N. californicus in two satsuma mandarin orchards on Jeju Island and found most N. californicus individuals on herbaceous weeds on the ground, rather than on satsuma mandarin trees or woody plants surrounding the orchards. Raworth et al (1994) also suggested that N. californicus climbed apple trees from the ground in spring in the south of France.…”

Molecular verification of dispersal of phytoseiid mites from groundcover plants to tree leaves in Japanese peach orchards

“…Dispersal of phytoseiid mites from groundcover to peach leaves Kawashima and Jung (2010) investigated the overwintering sites of N. californicus in mandarin orchards in Korea. They reported that most N. californicus were collected on herbaceous plants on the ground rather than on mandarin trees or woody plants surrounding the orchards.…”