Mass rearing Halotydeus destructor (Tucker) (Acari : Penthaleidae) for use in summer screening of Trifolium subterraneum (L.) for mite resistance

Abstract

Summary. Controlled environment experiments were conducted to establish some of the requirements for successful mass rearing of Halotydeus destructor (redlegged earth mite). Numbers of mites reared on Vicia sativa (common vetch) cv. Blanchefleur grown alone or on a mixture of vetch with Trifolium subterraneum (subterranean clover) cv. Goulburn, were significantly higher than those on subterranean clover or Arctotheca calendula (capeweed) alone. Populations reared on vetch grown in a sandy soil were significantly higher than those reared on vetch grown in a loamy soil, pure sand or pure loam. Covering the soil surface with a natural pasture mulch increased mite numbers compared with leaving the soil bare or placing plant pots inside ventilated cages. Subsequent changes in rearing methodology produced enough mites to enable summer screening of subterranean clover lines for resistance to H. destructorfor the first time. Over 20 000 mites can be produced from vetch at one time for screening tests throughout the year.

Mass rearing an earth mite to screen plants for resistance: A review

“…Mites are collected from the field and weighed onto the seedlings 6–8 days after sowing to give an estimated density of 10 000–15 000 mites/m 2 . For one winter screening experiment 45 000–100 000 mites are required (Thackray et al . 1997a).…”

“…While it is possible to field collect mites in the winter, in the summer active mites are not available, severely limiting the rate at which the plant germplasm collections can be screened (Thackray et al . 1997a).…”

“…Soil type and the surface covering affect humidity at the soil surface. Mites feeding on vetch have a multiplication fourfold greater when the soil is a sandy loam than with a sand‐peat mixture, river sand or pasture loam (Thackray et al . 1997a).…”

“…Vetch cv Blanchefleur is planted in sandy‐loam soil, mites added after 3 weeks, and transferred every 5 weeks to fresh plants, the soil surface is covered with sphagnum moss with either a Vaseline strip on the edge of the tote box to prevent the escape of mites or modified ventilated covers placed over the tote boxes to maintain humidity. Mite multiplication is five to sixfold greater once moss is introduced as a mulch and although the average multiplication is higher with the perspex covers it is more variable (Thackray et al . 1997a).…”

Soil microflora as hosts of redlegged earth mite (Halotydeus destructor)

“…Common vetch (Vicia sativa (L.)), faba beans (V. faba Harz.) This may be why heavy mulching of the soil surface, which can provide a suitable habitat for microflora, increases H. destructor's fecundity (Thackray et al, 1997). There is clear evidence, however, that the mites breed successfully in field plots of wheat and mite-resistant subterranean clover (Trifolium subterraneum (L.)) (Ridsdill-Smith et al, 1995).…”