Hymenoptera

Baumann, Julia, 2018, Tiny mites on a great journey - a review on scutacarid mites as phoronts and inquilines (Heterostigmatina, Pygmephoroidea, Scutacaridae), Acarologia 58 (1), pp. 192-251 : 208-209

Hymenoptera : ants

The majority of scutacarid mites living in associations with other animals can be found with another family of Vespoidea, the Formicidae , or ants (214 spp.). Most associated scutacarids belong to the genera Scutacarus and Imparipes ( Figures 11 , 12 ; Annex V-VII). A great variety of different mite taxa can be found as guests of ants (e.g. Vitzthum 1919, Campbell et al. 2013), and it is also common to encounter more than one scutacarid species within one single ant nest (e.g. Friedl 2000). Scutacarids are either phoretic on the ants or they live in ant nests, or both. Inside the ants’ nests, nest debris and (in army ants) temporary provisions are available ( Okabe 2013), both of which can become moldy and then serve as food sources for scutacarids. On the ants, scutacarids can be found on the thorax, between the coxae, but also on rather exposed parts like the ant’s legs or on the head (e.g. Paoli 1911, Rettenmeyer 1961a, Ebermann 1982, Elbadry et al. 1976).

From not further determined “ants”, 51 scutacarid species have been reported: Archidispus haarloevi ( Karafiat, 1959) , 13 Imparipes species , Pygmodispus calcaratus Paoli, 1911 and

36 Scutacarus species (e.g. Karafiat 1959, Mahunka 1981, 1986, Dobrev 1992; for other references see Annex V). For all other reports of associations between ants and Scutacaridae , at the least the subfamily of the host was given. Most scutacarid species occur together with Formicinae and Myrmicinae ( Figure 12 ; Annex VI, VII).

In the subfamily Formicinae , Archidispus intermissus ( Karafiat, 1959) , 28 Imparipes species , 2 Lophodispus species , 58 Scutacarus species and Thaumatopelvis reticulatus are present as associates (e.g. Karafiat 1959, Mahunka 1972b, 1977c, Khaustov 2008, Ebermann and Krisper 2014; for other references see Annex VI). The scutacarids could be detected in 5 ant genera, and the majority of all mite species (52 species) was present in the genus Lasius . Ants of this genus can occur in high population densities (e.g. L. alienus or L. niger ), they frequently are social parasites of other ants and often feed through trophobiosis in symbiosis with aphids ( Seifert 1996). Scutacarids can also often be found in associations with zoophagous Formica ants, further with the genera Camponotus and Paratrechina . There are even species associated with desert ants of the genus Cataglyphus, which are highly thermophilic scavengers feeding mostly on dead arthropods ( Lenoir et al. 2009).

Thirty-four Imparipes species , Lophodispus irregularis and 38 Scutacarus species have been reported from the subfamily Myrmicinae (e.g. Ebermann 1979, 1980a, b, Khaustov 2008, Ebermann and Krisper 2014; for other references see Annex VII). The mites have been found in association with ants belonging to 10 genera, and the largest number of mites (25 species) was present in the genus Myrmica . The genera accepted as hosts are characterized by different life styles, ranging from harvester ants feeding on seeds (e.g. Messor ) to zoophagous (e.g. Myrmica ) and omnivorous ants (e.g. Solenopsis ). The colony sizes of the hosts also vary, ranging from 40- 120 workers in Stenamma to some thousand workers in Aphenogaster ( Seifert 1996).

Scutacarids can also be associated with army ants of the subfamily Dorylinae (following the taxonomic classifaction by Brady et al. 2014). These ants are carnivorous, they raid for food in large groups, build extremely large colonies and the whole colonies emigrate periodically ( Rettenmeyer et al. 2011, Okabe 2013). Colonies of Dorylinae are home to several animals belonging to a variety of taxa, but their most abundant guests are mites ( Gotwald 1996, Rettenmeyer et al. 2011). Accordingly, Dorylinae also serve as hosts for scutacarids: 39 scutacarid species belonging to seven genera have been reported from five army ant genera (Annex V). The respective mites are 4 Archidispus species , 24 Imparipes species , Pygmodispus dorylini Mahunka, 1977 , Rettenmeyerella petropolitana solenifera Mahunka, 1977 , 2 Scutacaropsis species , 5 Scutacarus species and 2 Thaumatopelvis species ( Rettenmeyer 1961a, Mahunka 1977a,b, Ebermann 1980b, Berghoff and Franks 2007, Berghoff et al. 2009, Rettenmeyer et al. 2011). Within ants, Dorylinae display the highest diversity of scutacarids on genus level.

Six scutacarid species (3 Imparipes , Lophodispus tapinoma Sobhi & Hajiqanbar, 2017 and 2 Scutacarus ) were found in association with ants of the subfamily Dolichoderinae , either with members of the genus Tapinoma or with members of Liometopum ( Mahunka 1977c, 1982, Khaustov 2008; Annex V). Tapinoma ants are omnivorous and not sedentary, instead they often change the location of their nests, while Liometopum ants are sedentary, associated with trees and shrubs and they can also be minor pests in housing areas ( Hoey-Chamberlain et al. 2013). Only one scutacarid, Imparipes malus Khaustov, 2008 , has been reported from Ponera coarctata of the subfamily Ponerinae ( Khaustov 2008; Annex V). The concealed life style of this thermophile ant species makes it difficult to sample ( Seifert 1996, Wagner 2014), so intensified collections may reveal a higher number of associated scutacarids.

Figures

Figure 11 Number of scutacarid species belonging to different genera associated with ants (Formicidae). “Other genera” combineDiversipes, Lamnacarus, Lophodispus, Nasutiscutacarus, Parascutacarus, Reductacarus, Rettenmeyerella, Scutacaropsis, SymbolacrasisandThaumatopelvis.

Figure 12 Number of scutacarid species belonging to different genera associated with different subfamilies of ants (Formicidae).