Performance of eighteen tetranychid mite species (Acari: Tetranychidae) on borage and strawberry

Abstract

Borage (Borago officinalis L.) is anticipated as a banker plant in strawberry greenhouses to adopt integrated aphid management, because borage has a stimulatory influence on parasitoid wasps attacking aphids. However, before actually using borage, we had to answer the following question: will borage become a hotbed for spider mites? To investigate this, host plant suitability and acceptance by 18 tetranychid mite species were tested on borage and strawberry leaves. The mites were two Panonychus species, two Eotetranychus species and 14 Tetranychus species, including the green and red forms of T. urticae that were counted as separate species. Borage appeared an unsuitable host, because females of all 18 mite species did not lay eggs, females of most species could not survive for more than 5 days, and larvae of all 18 mite species did not develop to nymphal stages on borage. Conversely, strawberry was a suitable host for 13 of the 18 spider mite species: females laid eggs and about 90% of larvae successfully reached adulthood. Thus, these13 species have the potential to become pests of strawberry. Offering female spider mites the choice between interconnected borage and strawberry leaf discs, (1) most females moved from borage to strawberry except for the two Panonychus species and E. asiaticus, and (2) few females moved from strawberry to either borage or strawberry. Consequently, it is highly unlikely that borage will become a hotbed for any of the spider mite species.