Female Fighting and Host Competition Among Four Sympatric Species of \u3ci\u3eMelittobia\u3c/i\u3e (Hymenoptera: Eulophidae)

Abstract

Melittobia is a genus of parasitic wasps well known for high levels of inbreeding and violent male combat. Casual observations of groups of sisters of M. femorata placed with hosts revealed a surprising incidence of body mutilations (broken or missing tarsi, antennae, and wings). Replicated conspecific groups of 1, 2, or 3 females of M. femorata, M. digitata, and M. australica and interspecific groups of M. femorata and M. australica (2:1) were observed over their first 10 days in newly established cultures, and the incidence of mutilation was recorded. In some groups females were dye-fed, allowing us to subsequently chart their individual activity patterns on or near the host based on patterns of their colored fecal droppings. For M. australica and M. digitata, no conspecific females in any group size ever showed mutilation. However, in M. femorata nearly 3/4ths of the females in conspecific groups of two or three acquired body damage beginning about the time of first oviposition on the host. In 4 of 5 replicates of the interspecific groups, M. femorata females killed the female of M. australica. Patterns of dyed fecal droppings that developed over several days showed that individual females in groups of both M. femorata and M. australica increasingly restricted their activities to a small portion of the host. These “micro” territories were non-overlapping and appeared to be actively defended. In contrast, M. digitata females in groups never displayed obvious territoriality or interference. Possible reasons for these differences in female behavior are discussed

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