Ant protection of a Heteropteran trophobiont against a parasitoid wasp

Trophobiotic associations between Caternaultiella rugosa (Heteroptera; Plat aspidae) and two ant species, Camponotus brutus (Formicidae) and Myrmicaria opaciventris (Myrmicinae), were recorded at the base of the trunks of Brid elia micrantha (Euphorbiaceae). The bug colonies were generally sheltered i n pavilions built by the ants, but during periods of proliferation, part of the colonies developed outside the pavilions. We examined the protective a ctivity of the two associated ant species against an encyrtid parasitoid wa sp that parasitized egg masses of the bug. Egg masses situated outside the pavilions were significantly less parasitized on trees occupied by either a nt species than on experimental trees where ants were excluded by a sticky barrier. Egg masses were significantly less parasitized on trees occupied b y C. brutus than on those occupied by M. opaciventris, both inside and outs ide the pavilions. Moreover, they were less parasitized inside than outside the pavilions when protected by C. brutus. Inside the pavilions, parental care of the egg masses and first-instar nymphs was abandoned to the ants. I n contrast, outside the pavilions, the females of C. rugosa guarded egg mas ses and clusters of first-instar nymphs. Furthermore, adults and last-insta r nymphs grouped around and above first-instar nymphs, forming a protective shield. These groups formed and disintegrated daily, according to the atte nding ant's rhythm of activity.