The parasitic wasp Melittobia digitata Dahms (Hymenoptera: Eulophidae) is a gregarious external parasite of various insects, including the common wasp Trypoxylon politum Say (Hymenoptera: Sphecidae). Males of this species commonly engage in fierce, often fatal, fights with other males. The mandibles are the main weapons used, and injuries inflicted vary greatly in severity. This study had three objectives. The first objective was to determine if the presence of conspecificis shortened a male’s life. Isolated males raised with female pupae and adult females were found to have life spans significantly shorter than the control male lifespan. The second objective was to determine whether fighting behavior changed with age. The hypothesis was that older males whose energy reserves would be nearly depleted would be more subdued fighters relative to younger males. Isolated one-day-old and five-day-old inexperienced males were paired in observation arenas, and outcomes were recorded. Results supported the hypothesis; young males fought quickly and violently compared to older males. The incidence of fatal fights, however, remained the same among young and old males. The final objective was to determine if size differences exist between winning, losing and non-fighting males. The head width and tibia length of fighting and non-fighting males were measured. Winning males were found to be larger than losing males, and fighting males (winners and losers combined) were found to be larger than non-fighting males.
Species 1: Hymenoptera Eulophidae Melittobia digitata
Keywords: Chalcidoidea, Lethal Combat
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