Host defense inNicrophorus quadripunctatusagainst brood parasitism byPtomascopus morio(Coleoptera: Silphidae: Nicrophorinae)

Abstract

AbstractFew studies have been conducted on the host defenses of insects against brood parasitism. We investigated whether the silphid beetlePtomascopus morio, a brood parasite of related silphid speciesNicrophorus concolor, can also parasitize another silphid speciesNicrophorus quadripunctatusand the manner in whichN. quadripunctatusdefends itself against parasitism. Successful brood parasitism under natural conditions was not observed at the time of year whenP. morioandN. quadripunctatusare both reproductively active. Follow‐up experiments revealed thatP. morioattempts to oviposit nearN. quadripunctatusnests, but is rarely successful if adult hosts are present. WhenP. moriolarvae were experimentally introduced toN. quadripunctatusbroods, someP. moriolarvae survived when the host and parasite larvae were at the same stage. We concluded thatN. quadripunctatusdefends itself against brood parasitism in two ways: (1) potential brood parasites are repelled, thus limiting their access to the resource; and (2) the young of the parasitic species are killed.