Stratiolaelaps

t

Taxonomy

Stratiolaelaps scimitus (Womersley)

Diagnostic characters

Miles-group species (posterior margin of sternal shield convex or with median process, gnathotectum without lateral processes) with sharply tapering posterior dorsal shield and palp apotele with a small basal spine.

This short video shows Stratiolaelaps scimitus (often mistakenly identified and distributed as Stratiolaelaps miles or Hypoaspis miles) in action; both adults and nymphs are feeding on Western flower thrips 'pupae'. The mite is a soil-inhabiting generalist predator that captures the thrips when they leave plants and enter the soil to transform into adults. When thrips are not present the mite will feed and develop on other arthropods and nematodes in the soil.

Similar species

Key to Adult females of Species of Stratiolaelaps (from Walter & Campbell 2002)

1. Fixed digit of chelicera with 2 teeth anterior to pilus dentilis, followed by serrate region; margin of gnathotectum denticulate, with longer median and lateral processes; posterior margin of sternal shield concave.............................. lamington group (2)
   - Fixed digit of chelicera with 2 teeth to either side of pilus dentilis; margin of gnathotectum denticulate, with single, smooth median process; posterior margin of sternal shield irregularly convex or produced medially.............................. miles group (3)

2. Dorsal shield with 39 pairs of spatulate-mucronate setae, paired accessory setae px2, px3 present; postanal seta and marginal setae r6 and R1 spatulate..............................S. lamington
   - Dorsal shield with 37 pairs of spatulate-acuminate setae, paired accessory px setae absent; postanal seta and marginal setae r6 and R1 acicular.............................. S. womersleyi

3. Most dorsal shield setae relatively short, tips not exceeding next seta in series; setae J4 and J5 subequal, Z5 20–40% longer.............................. 4
   - Most dorsal shield setae relatively long (e.g., all podonotal setae except z1 are 51–65 µm), tips approaching or passing insertion of next seta in series; setae J4 and Z5 much longer than J5 (50–60% and 60–100% longer, respectively).............................. S. marilyn

4. Setae r6 similar toothers; dorsal setae of femora and genua of legs II and IV mostly spatulate; dorsal shield 585–690 µm long; fixed digit of male chelicera with one tooth posterior to pilus dentilis.............................. 5
   - Setae r6 simple; dorsal setae of femora and genua of legs II and IV simple; dorsal shield 540–590 µm long; fixed digit of male chelicera with 3–5 teeth posterior to pilus dentilis.............................. S. lorna

5. Dorsal shield tapering gradually after level of setae S2; postanal seta short, only about 60% length of paranal setae; palp apotele with 2 subequal tines.............................. S. miles Evans and Till 1966Evans and Till 1966:
   Evans GO, Till WM. 1966. Studies on the British Dermanyssidae (Acari: Mesostigmata). Part II. Classification. Bulletin of the British Museum (Natural History) Zoology 14: 107–370.
   - Dorsal shield tapering sharply after level of setae S2; middle article of chelicera >260 µm long; postanal and paranal setae subequal in length; palp apotele with 2 subequal tines and a small basal tine.............................. S. scimitus (Womersley)

Ecology and distribution

Species of Stratiolaelaps are predatory and some are used in greenhouses against thrips and fungus gnats; S. scimitus is a cosmopolitan tramp species that is often mistaken for S. miles and is often marketed under the names Hypoaspis miles or S. miles.

References

• Aswegen and Loots 1970Aswegen and Loots 1970:
  Aswegen PIM van, Loots GC. 1970. A taxonomic study of the genus Hypoaspis Canestrini sens. lat. (Acari: Laelapinae) in the Ethiopian region. Publicações Culturais da Companhia de Diamantes de Angola, Lisboa 82: 167–214.
• Berlese 1979 [1892]Berlese 1979 [1892]:
  Berlese A. 1979. Acari, Myriopoda et Scorpiones hucusque in Italia reperta, 63, 17 pp. + Plates 1-10. Junk, The Hague and Antiquariaat Junk, Amsterdam. (Original work published 1892)
• Berlese 1916Berlese 1916:
  Berlese A. 1916. Centuria seconda di Acari nuovi. Redia 12: 125–177.
• Chambers et al. 1993Chambers et al. 1993:
  Chambers RJ, Wright EM, Lind RJ. 1993. Biological control of glasshouse sciarid flies (Bradysia spp.) with the predatory mite, Hypoaspis miles, on cyclamen and poinsettia. Biocontrol Science and Technology 3: 285–293.
• Evans and Till 1966Evans and Till 1966:
  Evans GO, Till WM. 1966. Studies on the British Dermanyssidae (Acari: Mesostigmata). Part II. Classification. Bulletin of the British Museum (Natural History) Zoology 14: 107–370.
• Gilyarov and Bregatova 1977Gilyarov and Bregatova 1977:
  Gilyarov MS, Bregatova NG, eds. 1977. Handbook for the identification of soil-inhabiting mites, Mesostigmata. Zoological Institute of the Academy of Sciences, Petrograd.
• Karg 1993Karg 1993:
  Karg W. 1993. Acari (Acarina), Milben Parasitiformes (Anactinochaeta) Cohors Gamasina Leach, Raubmilben. Die Tierwelt Deutschlands 59: 1–523.
• Tenorio 1982Tenorio 1982:
  Tenorio JM. 1982. Hypoaspidinae (Acari: Gamasida: Laelapidae) of the Hawaiian Islands. Pacific Insects 24: 259–274.
• Walter and Campbell 2003Walter and Campbell 2003:
  Walter DE, Campbell NJH. 2003. Exotic vs endemic biocontrol agents: Would the real Stratiolaelaps miles (Berlese) (Acari: Mesostigmata: Laelapidae) please stand up? Biological Control 26: 253–269.
• Wright and Chambers 1994Wright and Chambers 1994:
  Wright EM, Chambers RJ. 1994. The biology of the predatory mite Hypoaspis miles (Acari: Laelapidae), a potential biological control agent of Bradysia paupera (Dipt.: Sciardiae). Entomophaga 39: 225–235.
• Womersley 1956Womersley 1956:
  Womersley H. 1956. On some new Acarina-Mesostigmata from Australia, New Zealand and New Guinea. Journal of the Linnean Society of London, Zoology 42: 505–599.
• Zumpt and Patterson 1951Zumpt and Patterson 1951:
  Zumpt F, Patterson PM. 1951. Further notes on laelaptid mites parasitic on vertebrates. A preliminary study to the Ethiopian fauna. Journal of the Entomological Society of Southern Africa 14: 63–93.