N m Zealand Entomologist, 1996, Vol. 1961Aculodes mckenxiei (Acari: Eriophyidae) newly recorded in NewZealand and its association with other eriophyids inSouth Island pastures
P.L. GUY'& D.M. GOULD''Department of Botany and 'Department of Anatomy and StructuralBiology, University of Otago, Box 56 Dunedin, New Zealand
ABSTRACTThis is the first record ofAculodes rnckenziei (Keifer) in New Zealand. It was associatedwith the eriophyids Ahacarus hystrix and Aceria spp o n Loliurn spp in South Island
pastures and was the most abundant eriophyid on pasture grasses from 1992-95. Noneof the fungi reported to parasitize eriophyid mites were detected during the survey.
Keywords:Acarina, Eriophyidae, Aculodes mckenziei, Abacarus hystrix, Aceria spp ryegrass
mosaic virus, pasture, New Zealand.

INTRODUCTION
All of the 2400 species of eriophyid mites (be onging to 224 genera) so far described
are phytophagous. Most are monophagous an!l the effects they cause on their hosts
range from inconspicuous damage of epidermal cells through to tissue deformation
and retardation of plant growth. Aculodm mckenziei (Keifer) has been collected fromLoliurn spp in Europe (Mulligan 1960), North America (Slykhuis 1972) and Australia(Frost et al. 1990) and causes little damage to its hosts. At least 11 species of eriophyid
mites transmit plant viruses (Boczek & Griffiths 1994). There have been a number ofstudies on Aceria tulipae (Keifer), the vector of wheat streak mosaic virus (WSMV), andAbacarus hystrix (Nalepa), the vector of ryegrass mosaic virus (RgMV), which is often
associated with A. mckenziei (Slykhuis 1972).
RgMV is spread between sites by A. hystm'x while mowing is probably more importantin localized spread of the virus. It is considered a serious pathogen of ryegrass in Europe
and North America and its impact on New Zealand pasture production is currently
being investigated (Guy 1993).As part of this investigation, eriophyid mites from ryegrass
pastures in Canterbury, Otago and Southland were collected and identified.
METHODS
Mites were observed in situ using a dissecting microscope and then carefully removed
from the veinal grooves of Arrhenatherum elatius, L. multijorurn and I,. perenneleaf blades.
They were cleared and expanded in Keifer's A solution and rinsed with water before
examining under the microscope (Slykhuis 1972 ) . Alternatively, dead mites weremounted in lactophenol cotton blue, warmed gently over a flame, and examined forfungal mycelium.
For scanning electron microscopy, leaf pieces o r individual mites were freezesubstituted using 1% OsO,, critical-point dried and sputter coated using gold-palladium
before examination or simply attached to a stub and plunged into liquid nitrogen
immediately before examination.
The mites were identified using the keys of Jeppson et al. (1975) and Manson (1984)
with reference to Keifer (1945).
RESULTS AND DISCUSSIONAt least three species of mites were identified. The lack of an anterior lobe gave Aceria
spp a blunt-ended appearance (40x magnification) which readily distinguished themfrom Aculodes mckenziei and Abacarus hystrix which were much more crescent shaped

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Figs 1-3: Aculodes mckenziei. 1, dorsal view of Aculodes mckenziei in a veinal groove of Lolium multiflorum leaf
blade; 2, lateral view of thanosomal shield and legs; 3, coxal and genital region (female)(lateral view) under the dissecting microscope. These latter two species could only bedistinguished as slide-mounted specimens (400x magnification) by the presence or absence ofa broad mid-dorsal ridge on A. hystrix and A. mckenziei respectively. A. mckenziei is shown inFigs 1-3.
A. mckenziei was common on L multiflorum and L. perenne and occasionally observed on A.
elatius. It was present throughout the year and did not cause any conspicuous damage to its
hosts.

Nm Zealand Entomologist, 1776, Vol. 1763A. hystrix was often associated with A. mckenziei on L. multijlorum and L. perenne but wasalways much less abundant. This is in contrast to a previous study in California whichshowed that A. mckenziei predominated during the cooler months while A. hystrix
predominated during spring and autumn Ueppson et al. 1975). Climatic differences
between New Zealand and California may account for the apparent discrepancy.
The association between A. mckenziei and A. hystrix has been previously reported(Mulligan 1960, Lewis & Heard 1981) and is of particular interest because A. hystrz'xis areported vector of ryegrass mosaic virus while A. mckenziei is not. It is believed that highpopulation densities trigger the dispersal of A. hystrix however it is not known whether
high densities of A. mckenziei will trigger A. hystrix dispersal and therefore affect therate of spread of RgMV.
Aceria spp were abundant at some sites during summer and often associated withA . mckenziei on L . perenne. The only eriophyid recorded on grasses in New Zealand byManson (1984) is A . tulipae however individuals in this study did not always key
satisfactorily to this species. The Aceriamites are better described as Nalepa's tenuis (1891)
series of eriophyids (Jeppson et al. 1975). This problem may have been previously
encountered when Martin (1984) recorded Aceria sp and Aceria sp (nr tulipae) as
components of the New Zealand pasture fauna. A . tulipaeis a pest of New Zealand garlic(Manson 1984) and is the vector of wheat streak mosaic virus, which has not been reportedfrom New Zealand. In view of the abundance of Aceria on susceptible L o l i u m s p p , WSMV
and other Acem'a transmitted viruses should be resurveyed.
No fungal mycelia were observed on any of the dead mites examined. Previous studies
have shown that the grass-infesting eriophyids are parasitized by Hirsutella spp, Ramularia
spp, Spermospora lolii and Verticillium lecanii (Lewis & Heard 1981, Minter et al. 1983). Of
these, only K lecanii is known from New Zealand (as a parasite of the glow worm
Arachnocampa luminosa Skuse (Diptera: Keroplatidae)) (McKenzie 1988). Further work
will be necessary to establish whether the other fungi are present and whether they areaffecting eriophyid populations in New Zealand.
ACKNOWLEDGEMENT
PLG gratefully acknowledges receipt of a grant from the Vernon Willey Trust to study
RgMV in New Zealand pastures.
REFERENCES
Boczek,J.; Griffiths, D.A. 1994: Structure and systematics of eriophyid mites (Acari: Eriophyoidea)
and their relationship to host plants. pp119-129 In Williams, M.A.J. (Ed) Plant Galls. TheSystematics Association Special Volume No 49. Oxford, Clarendon Press. 488pp.
Frost, W.E.; Eagling, D.R.; Manson, D.C.M. 1990:Abacarus hystn'x (Nalepa) (Acarina: Eriophyidae)
newly recorded in Australia. Journal ofthe Australian Entomological Society 29 182.
Guy, P. L. 1993: First record of ryegrass mosaic virus and its mite vector Abacarus hystrix (Nal.) in
New Zealand. New Zealand Journal ofAgricultura1 Research 3 6 377-379.
Jeppson, L. R.; Keifer, H. H.; Baker, E. W. 1975: Mites Injurious to Economic Plants. Berkeley,
University of California Press. 615pp.
Keifer, H. H. 1945: Eriophyid studies XIV. Bulletin of the California Department ofAgnculture 34: 1838. Lewis, G.C.; Heard, AJ. 1981: The incidence in ryegrass (Lolium spp) crops of eriophyidmites, vectors of ryegrass mosaic virus. Proceedings ofthe 3rd Conference on VirusDiseases ofGramineae
in Europe: 89-98.
Manson, D.C.M. 1984: Eriophyinae (Arachnida: Acari: Eriophyoidea). Fauna of New Zealand 5: 1123.
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McKenzie, E.H.C. 1988: Verticillium lecanii (Zimmerman) Viegas. International Collection ofMicroorganismsfrom Plants. Catalogue Accessions 1-9519. Plant Diseases Division, DSIR Auckland, NewZealand, p 127.

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Minter, D.W.; Brady, B L ; Hall, R.A. 1983: Five hyphomycetes isolated from eriophyid mites.
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