Dumpster diving xanthopygine rove beetles

Let's face it, a lot of beetles are associated with ants. But few go to the extremes that rove beetles go to make themselves at home with the ants. Many rove beetles not only look like ants, they also smell like ants. If you want to see some really cool, yet ultimately bizarre beetles, I suggest you read the blog post by Joe Parker and Taro Eldredge on Pselaphinae and Aleocharinae myrmecophiles.

A few xanthopygine rove beetles are known to be associated with ants but these beetles are typically found on ant refuse piles (=dumpsters). The refuse piles are nutrient-rich, thriving micro-communities that support many types of arthropods, fungi and bacteria. Most rove beetles are there to feed on the fly larvae but we really do not know the details. Navarrete-Heredia (2001)* lists 65 genera (148 species) of rove beetles associated with leaf cutter ants, either Atta or Acromyrmex. Several xanthopygine beetles made the list, including species from the genera Glenus, Paraxenopygus, Tricholinus, Scariphaeus, Smilax and Plociopterus.

Glenus jelskii Solsky is known from refuge piles of Atta sexdens (Scheerpeltz 1936)

One striking feature of all these xanthopygines is that they are good-looking beetles. I would have expected that an insect hiding in a refuge pile would be dull-colored (why spend energy on coloration?) but most of these have shining metallic colorations with bright yellows and reds. Not sure if this is a plesiomorphic characteristic (most xanthopygines have impressive metallic coloration) or if there is an adaptive significance of the coloration.

Some xanthopygines take their Hymenoptera associations one step further: they are known from debris piles of wasps and stingless bees. One of largest (almost 3 cm) known xanthopygine rove beetle, Triacrus dilatus, is known from the debris piles of the wasp Stenopolybia Agelaia vicina (Wasmann 1902).

Triacrus dilatus Nordmann

A couple more species, Xanthopygus cyanipennis and Xenopygus analis have been recorded from the nest of Trigona clavipes (a stingless bee) (Luderwalt 1917), although both of these instances might be accidental/opportunistic. Xenopygus analis is extremely widespread (Mexico to Brazil, introduced in Hawaii) and will feed on anything. A while back I posted a video clip of X. analis eating rotting Gustavia superba fruits.

A lot of cool work remaining to be done here, both systematic and ecological, to understand these associations and map the evolution of these behaviors.


*Thanks to Adam Brunke for providing some of these references.

References

Luderwalt H (1917) Biologishes uber brasilianische Staphyliniden. Z. Wiss. Insektenbiol. 13: 44-47

Navarrete-Heredia JL (2001) Beetles associated with Atta and Acromyrmex ants (Hymenoptera: Formicidae: Attini). Transactions of the American Entomological Society 127(3): 381-429.

Scheerpeltz O (1936) Die von Prof. Dr. H. Eidmann gelegentlich seiner im Jahre 1933 nach Brasilien unternommenen Studienreise aufgesammelten Staphyliniden. I. Die in den Nestern von Atta sexdens L. aufgefundenen Staphyliniden, nebst einigen Bemerkungen uber die Gattung Scariphaeus Er. Archiv fur Naturgeschichte (N.F.), 5, 483–540.

Wasmann E (1902) Riesige Kurzflügler als Hymenopteren-Gäste. (132 Beitrag zur Kenntniss der Myrmekiphilen und Termitophilen.). Insektenborse 19: 267–268, 275–276, 282.