Archive for July, 2012

Moving to and fro on leaves: Phytoseiidae

July 20, 2012

Phytoseius oreillyi – Peter O’Reilly’s Leaf Rover

There are good mites, and bad mites, and many that are indifferent, but not many mites that are our friends. The Phytoseiidae (Acari: Mesostigmata), however, are our friends. This is because we share a common interest: spider mites (many of which are really bad mites). The species pictured above belongs to the type genus of the family: ‘Phyto’ (Greek for plant) and ‘seius’ (Greek for one who moves to and fro, or  shakes). The generic name perfectly captures the Gestalt of the family: they are mites that scurry across leaves looking for other mites to eat. This species was named for (Big) Peter O’Reilly of OReilly’s Guesthouse in Lamington National Park, Queensland. Although Peter preferred birds, he was always supportive of scientific research, even on mites. This species lives on the leaves of rainforest trees in the canopy of Lamington National Park. Peter seemed delighted that I named the mite for him, but Peter was never less than polite, so he may have been humouring me.

Man’s best mite friend: Phytoseiulus persimilis

O’Reilly’s Leaf-Roamer may or may not be of help to us in our long war with spider mites, but its cousin the Chilean Predatory Mites (Phytoseius persimilis) certainly is. The common name may or may not be accurate. The species was first described from the Mediterranean Region by the great Belgian-French acarologist Claire Athias-Henriot, but it was a cosmopolitan synathrope long before it was described. Our agricultural systems are very favourable to spider mite outbreaks. Phytoseiulus persimilis is a specialist predator  of spider mites, especially those that produce dense webs of silk such as the Two-spotted Spider Mite (Tetranychus urticae), a very bad mite. Although it tends to follow us around, good biological control requires using your predators at the appropriate time in the prey’s population cycle. Fortunately, nowadays you can buy boxes of Chilean Predatory Mites to sprinkle on your greenhouse crops, strawberries, and other crops to fend off damage by spider mites.

Amblyseius sp. – a genus with many good mites

A triple tribute to Funk: Funkotriplogynium iagobadius

July 7, 2012

Juvenile antennophorine mite

For no particular reason, other than it being a really good mite, I offer a view of a very dead juvenile collected in association with the infamous Funkotriplogynium iagobadius Seeman & Walter, 1997. Mites in the Antennophorina (Mesostigmata) are best known as associates of large arthropods, especially beetles and millipedes, but some live with ants, bees and termites, and others with cockroaches and earwigs living in stable habitats such as under rocks and in logs. For example, Paradiplogynium nahmani Seeman, 2007, was described from Australia’s Colossus Earwig Titanolabis colossea (Dohrn 1864) – at about 6 cm long, one of the World’s largest Dermaptera. Antennophorine mites are no slouches when it comes to size either. Adult Diplogyniidae, the earwig mite’s family, usually approach a millimetre in length and some of the Megisthanus on passalid beetles reach 5-6 mm in body length, as large as some ticks. Diplogynium Canestrini, 1888, type genus of Diplogyniidae Trägårdh, 1941, is but one of forty-odd genera and almost 100 described species in that family , and although the largest family of Antennophorina, is but one among 21 families grouped in 7 superfamilies.

Mop-like cheliceral excrescences of Micromegistus – an associate of carabid beetles

In spite of these mites being relatively large and living on often well-studied arthropods, little is know of their life history. The ant associates in Antennophorus make their living by making ants regurgitate food (sounds disgusting, but it’s a life). But for others it isn’t clear: the adults hang out on their hosts doing something with their mouthparts from which large mop-like excrescences dangle. What they are doing, however, is a mystery. Some authors have hypothesized that they feed on the ‘dermal secretions’ of their hosts. The larvae and nymphs are usually not found on the arthropods, so they are almost completely unknown, but some have been found wandering in galleries and have been thought to ‘scavenge’ or feed on fungi, the usual default guesses for  ‘I don’t know’.

Mysterious mouthparts of Megisthanus – an associate of passalid beetles

Fortunately, not all Antennophorina are inveterately found on large arthropods: a few are more or less free-living. One such group is the rather plesiotypic family Triplogyniidae, based on the then new genus and species Triplogynium krantzi Funk, 1977, from Central Africa. In 1985 AK Datta described a second genus in the family and added Dick Funk’s name to create the rather earthy, but not at all syncopated, name Funkotriplogynium. This latter genus also occurs in Australia and a student, Owen Seeman, and I were able to both observe feeding by the adults and describe the juveniles. This gave us an indication that predation was the basal mode of feeding in Antennophorina and gave Owen the opportunity to win fame and infamy with his species name. Owen has a lot of things to answer for (my having to feed chickens the first thing in the morning immediately comes to mind), but he has earned his spurs as an acarologist by almost singlehandedly exposing the mysteries of antennophorine development and ecology. Although much remains to be explained, including the function of those fabulous excrescences, it seems clear now that taking a bite out of whatever arthropods or worms are encountered while wandering in the galleries and nests of their hosts is the first thing on the minds of many antennophorines.

These teeth were made for biting and that’s just what they do

References:

Datta AK. 1985. A new genus and species of the family Triplogyniidae (Acari: Mesostigmata) from Assam, India. Indian Journal of Acarology 9: 48-56.

Funk RC. 1977. Triplogynium krantzi n.g., n. sp., type of Triplogyniidae (Mesosligmata: Celaenopsoidea). International Journal of Acarology 3: 71-79.

Seeman OD & Walter DE. 1997. A new species of Triplogyniidae (Mesostigmata: Celaenopsoidea) from Australian rainforests. International Journal of Acarology 23: 49-59.

Seeman OD. 2000. The immature stages of the Fedrizziidae (Mesostigmata: Fedrizzoidea). Acarologia 41: 39-52.

Seeman OD. 2007. A new species of Paradiplogynium (Acari: Diplogyniidae) from Titanolabis colossea (Dohrn) (Dermaptera: Anisolabididae), Australia’s largest earwig. Zootaxa 1386: 31-38.

Seeman O.D. 2012  Larva and deutonymph of Promegistus armstrongi Womersley (Acari: Mesostigmata: Trigynaspida: Promegistidae). Memoirs of the Queensland Museum – Nature 56(1): 255-269.