Non-crop host plants of Tetranychus spider mites (Acari: Tetranychidae) in the field in Okinawa, Japan: Determination of possible sources of pest species and inference on the cause of peculiar mite fauna on crops

Abstract

The species composition of spider mites on crops in Okinawa is peculiar in that Tetranychus okinawanus and T. piercei are dominant on most islands, whereas T. urticae (green form) and T. kanzawai are not. To determine the source plants of Tetranychus species infesting crops, as well as to contribute to our understanding of the cause of this peculiar mite fauna, we collected Tetranychus mites on non-crop plants throughout Okinawa (more than 450 sites on 15 islands) and identified them. Except in the case of T. parakanzawai, the species frequently found on crops tended to occur frequently on non-crop plants, suggesting that the peculiar species composition on crops reflects that also on non-crop plants. T. parakanzawai has been rarely found on crops but frequently found on particular non-crop plants, possibly due to the narrower host range of this species. The type of host plants varied among mite species; for example, T. okinawanus was frequently found on indigenous plants inhabiting the seashore and invasive weeds, T. piercei and T. parakanzawai on inland indigenous plants, T. urticae (green form) on invasive weeds, and T. neocaledonicus on introduced trees. These results are of great significance when considering vegetation control as a tactic for the integrated management of spider mites.

Geographic distribution of phytoseiid mite species (Acari: Phytoseiidae) on crops in Okinawa, a subtropical area of Japan

“…New distribution records of mite species were determined by referring to Ehara and Amano (2004) and Ehara (2007). Most of the co‐occurring spider mite species have already been identified, but some were newly identified in the present study (see Ohno et al . 2009, 2010).…”

“…New distribution records of mite species were determined by referring to Ehara and Amano (2004) and Ehara (2007). Most of the co-occurring spider mite species have already been identified, but some were newly identified in the present study (see Ohno et al 2009Ohno et al , 2010. The raw collection and species identification data used in the present study are presented in Appendix S1 in Supporting Information.…”

Cooperative web sharing against predators promotes group living in spider mites

“…Although the two spider mite species co-occur on the same host plants (Kondo and Takafuji 1985;Morishita 1992Morishita , 1997Takafuji and Morishita 2001;Osakabe et al 2002;Ohno et al 2010) and have the potential to live closely together on a single leaf, as demonstrated here, strong natural selection for heterospecific cooperation (in comparison to conspecific cooperation) remains questionable. The apparent cooperation between heterospecifics may rather be a byproduct of cooperation between conspecifics that live together.…”

“…They live together on dozens of wild and cultivated host plant species and often co-occur on the same plant specimen (Kondo and Takafuji 1985;Morishita 1992Morishita , 1997Takafuji and Morishita 2001;Osakabe et al 2002;Ohno et al 2010). Mated mite adult females (founder individuals) construct complicated, irregular webs on leaf surfaces (Saito 1983), feeding and reproducing inside the webs, and ultimately forming aggregations that include juveniles that also contribute to the web building (Hazan et al 1974;Clotuche et al 2009).…”

An Area-wide Occurrence of the Two-Spotted Spider Mite, Tetranychus urticae (Acari: Tetanychidae), Observed in Wax Gourd (Benincasa hispida) Greenhouses on Miyako Island, Okinawa, in 2009, and Subsequent Disappearance of the Spider Mites

“…'Genus unknown' indicates a species that was not identified due to lack of adult specimens. A newly recorded host for each mite species is denoted with an asterisk [determined by referring to Migeon andDorkeld (2006-2010) and Ohno et al (2010Ohno et al ( , 2011. Oligonychus modestus and Tetranychina harti were newly found on Miyako Island.…”