The Biology and Behaviour of Redlegged Earth Mite and Blue Oat
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52 Plant Protection Quarterly Vol.10(2) 1995 Halliday, R.B. (1991). Taxonomic back- ground of the redlegged earth mite The biology and behaviour of redlegged earth mite Halotydeus destructor (Tucker) (Acarina: Penthaleidae). Plant Protection Quar- and blue oat mite on crop plants terly 6, 162-5. Jack, R.W. (1908). The earth flea: A com- Garrick McDonaldA, Kylie MoritzA, Eve MertonB and A.A. HoffmannB mon pest of winter vegetables. The Ag- A Plant Sciences and Biotechnology, Agriculture Victoria, La Trobe ricultural Journal of the Cape of Good Hope 32, 615-20. University, Bundoora, Victoria 3083, Australia. B James, D.G. (1995). Biological control of School of Genetics and Human Variation, La Trobe University, Bundoora, earth mites in pasture using endemic Victoria 3083, Australia. natural enemies. Proceedings of the sec- ond national workshop on redlegged Summary earth mite, lucerne flea and blue oat Earth mites are one of the major deter- the redlegged earth mite (Halotydeus de- mite, pp. 69-71. rents to the successful establishment of structor Tucker) although blue oat mite Löhr, B., Varela, A.M. and Santos, B. winter oilseeds, particularly canola. In (Penthaleus major Duges), true wireworms (1990). Exploration for natural enemies order to understand how crop manage- (Fam. Elatridae), false wireworms (Fam. of the cassava mealybug, Phenacoccus ment practices may impact on mites and Tenebrionidae), cutworms (Agrotis infusa) manihoti (Homoptera: Pseudococcidae), their damage, we have commenced a and slugs are also important. in South America for the biological con- study of the relationships between the The aim of our research is to evaluate trol of this introduced pest in Africa. mites and oilseed, grain legume and ce- various cultural control and plant resist- Bulletin of Entomological Research 80, real crop plants. Halotydeus destructor ance options to minimize the impact of 417-25. were shown not to be attracted to lupins, pests on the establishing crop, particu- Meyer, M.K.P. (1981). Mites pests of crops wheat or oats, and their survival and fe- larly canola (Brassica napus). We are, for in southern Africa. Science Bulletin, De- cundity were significantly lower on example, interested in how different rota- partment of Agriculture and Fisheries, Re- these than on other plant types. This tion sequences may affect the build up in public of South Africa 397, 1-92. suggests that such crops, particularly lu- earth mite populations prior to a canola Narayan, D.S. (1962). Morphological, bio- pins, used in rotations prior to canola, planting. logical and ecological studies on the could minimize the in-paddock infesta- Earth mites are regarded as ubiquitous winter grain mite, Penthaleus major tions of mites. Preliminary screening pests of most field crops including cereals (Duges), Penthaleidae: Acarina Part 1. tests for H. destructor resistance has also although there is anecdotal evidence that Journal of the Zoological Society of India shown that some northern hemisphere H. destructor has a low preference for the 14, 45-63. varieties of Brassica napus are prone to latter. Thus, a crop rotation sequence with Newman, L.J. (1931). The principle insect significantly less cotyledon damage wheat preceding canola should reduce pests of tobacco. Journal of the Depart- than local varieties. Notably, survival mite populations, possibly to below dam- ment of Agriculture of Western Australia and fecundity of H. destructor on age threshold levels, for subsequent 8, 520-41. B. napus was low even on susceptible crops. Another pest management option Qin, T.K., Gullan, P.J., Beattie, G.A.C., varieties, indicating that the species al- for mites in winter oilseeds may be the Trueman, J.W.H., Cranston, P.S., ready has a level of partial resistance. development of resistant plant varieties. Fletcher, M.J. and Sands, D.P.A. (In On the one variety tested (Oscar), In this paper, we summarize our progress press). The current distribution and Penthaleus major caused only half the in laboratory studies of the relationships geographical origin of the scale insect damage of H. destructor. between mites and crop and crucifer Ceroplastes sinensis (Hemiptera: weed plants. We include preliminary re- Coccidae). Bulletin of Entomological Introduction sults from feeding/choice studies of mites Research. Winter oilseeds are highly vulnerable to on oilseed, legume and cereal crop plants, Tucker, R.W.E. (1925). The black sand pest damage during the first weeks after studies of H. destructor population growth mite: Penthaleus destructor n. sp. Ento- germination. The most significant pest is characteristics on crop and pasture plants, mology Memoirs, Department of Agricul- ture, Union of South Africa 3, 21-36. 3.5 Wallace, M.M.H. and Mahon, J.A. (1971). Distribution of Halotydeus destructor 3 and Penthaleus major (Acari: Eupodidae) in relation to climate and land use. Aus- 2.5 tralian Journal of Zoology 19, 65-76. Womersley, H. (1933). On some Acarina from Australia and South Africa. Trans- 2 actions of the Royal Society of South Aus- tralia 57, 108-112. 1.5 Womersley, H. (1941). The redlegged earthmite (Acarina: Penthaleidae) of 1 Australia. Transactions of the Royal Soci- Multiplication index ety of South Australia 65, 292-4. 0.5 Weeks, A., Fripp, Y.J. and Hoffmann, A.A. (1995). Population structure of redlegged earth mite and blue oat mite 0 vetch faba field canola lupins wheat oats populations in Victoria. Proceedings of medic beans peas the second national workshop on redlegged earth mite, lucerne flea and Figure 1. Net reproductive rate of H. destructor on various crop and pasture blue oat mite, pp. 33-5. hosts. The dotted line indicates the net population replacement rate. Plant Protection Quarterly Vol.10(2) 1995 53 and screening experiments for H. destruc- Experiments B. napus hybrids, if hybridization proves tor resistance in a variety of oilseed Feeding preferences. Choice and no possible. Ten seedlings of each line/spe- brassicas and weedy crucifers. choice experiments, replicated six times, cies were grown in each of ten replicate were conducted with H. destructor and containers and maintained for one week Methods P. major on common vetch, canola, lupins, at 25°C. Mites were collected from a local wheat, medic and capeweed. The experi- pasture and 100 H. destructor were added Assay methods ments were conducted in petri dishes to each pot, except for five pots of var. Single mite and small cohort experi- containing a thin layer of moistened fine Oscar which received 100 P. major each. ments. A technique to study single or white sand, five young adult mites and Damage scores on the cotyledons were re- small numbers of mites over protracted the test leaf/leaves. In the no-choice ex- corded after 2, 5 and 8 days. periods was developed using 7 cm petri periment, the mites were offered a single dishes with leaf cuts and mite(s). The leaf section (4–8 cm), cut from a fully de- Results dishes were lined with fine grade filter veloped leaf of the test plant. In the choice paper containing a moisture pad (a experiment, a leaf cut of vetch and the Feeding preferences gauze-covered vial cap containing cotton host plant were offered. The number of In the absence of a choice of hosts H. de- wool) and were sealed with parafilm. mites on or off the plant was recorded structor spent significantly (P<0.001) Whole plant experiments. Plants were every five minutes for an hour. more time feeding from vetch, medic and grown in a sterilized potting mix in 10 cm Population growth characteristics on capeweed (>50% of total time) than on pots. A 9 cm diameter clear plastic dome, crop plants. H. destructor survival and re- canola, lupins or wheat (<10% of total constructed from the middle and upper productive rate were measured on each of time) (Table 1). When H. destructor were section of a 1.25 L polyethylene seven host plants (canola, lupins, faba offered vetch as a choice to any of the terephthalate (PET) bottle, was firmly fit- beans, field peas, wheat, oats, white clo- other hosts, significantly more time ted into the rim of a pot by means of self ver). Four plants of each species were (P=0.05) was spent feeding on canola and adhesive urethanefoam tape. The dome grown in ten replicate 10 cm pots until capeweed (>20% of total time) than on contained four 5 cm diameter gauze they were about 14 days old (10–15 cm lupins, wheat or medic. In both series of vents. Each pot was watered by keeping it high). Fifty young adult H. destructor experiments, the mites were attracted to in an 11 cm diameter saucer (plastic food were placed on each plant. After 10 days the lupins and wheat for less than 10% of container) which was partly filled with and 14 days, the number of eggs laid and the time. P. major had less distinct prefer- water once weekly. The resistance screen- the surviving mites were counted and the ences. The mites spent significantly more ing experiments were also undertaken in latter removed. After a further 28 days, time (P<0.01) on capeweed than on the PET bottles, but these had the bottom re- the next generation of mites and their other tested plants, and showed least tained and the neck removed. Sterilized eggs were counted. The experiments were preference for vetch. When offered vetch potting mix (10 cm) was added and the concluded after six weeks when host as a choice to each of the test plants, seeds were sown directly. The tops were quality had declined. P. major spent significantly less time on sealed with perforated cling wrap plastic. Resistance screening experiments. Six lupins than on medic or capeweed All experiments, except the resistance distantly related lines of B.