0 M M Ero C J Neale E Hamacek T Peek A R Clarke 2011 Preference and performance of Diachasmimorpha kraussii (Fullaway) (Hymenoptera: Braconidae) on five commercial fruit species Journal of Applied Entomology 135 3 214-224 <p><em>Diachasmimorpha kraussii </em>is a polyphagous endoparasitoid of dacine fruit flies. The fruit fly hosts of <em>D. krausii</em>, in turn, attack a wide range of fruits and vegetables. The role that fruits play in host selection behaviour of<em> D. kraussii </em>has not been previously investigated. This study examines fruit preference of<em> D. kraussii </em>through a laboratory choice-test trial and field fruit sampling. In the laboratory trial, oviposition preference and offspring performance measures (sex ratio, developmental time, body length, hind tibial length) of<em> D. kraussii </em>were investigated with respect to five fruit species [<em>Psidium guajava </em>L. (guava),<em> Prunis persica </em>L. (peach), <em>Malus domestica </em>Borkh. (apple), <em>Pyrus communis</em> L. (pear) and<em> Citrus sinensis </em>L. (orange)], and two fruit fly species (<em>Bactrocera jarvisi </em>and <em>B. tryoni</em>). <em>Diachasmimorpha kraussii </em>responded to infested fruit of all fruit types in both choice and no-choice tests, but showed stronger preference for guava and peach in the choice tests irrespective of the species of fly larvae within the fruit. The wasp did not respond to uninfested fruit. The offspring performance measures differed in a non-consistent fashion between the fruit types, but generally wasp offspring performed better in guava, peach and orange. The offspring sex ratio, except for one fruit/fly combination (<em>B. jarvisi </em>in apple), was always female biased. The combined results suggest that of the five fruits tested, guava and peach are the best fruit substrates for <em>D. krausii</em>. Field sampling indicated a non-random use of available, fruit fly infested fruit by <em>D. kraussii</em>. Fruit fly maggots within two fruit species,<em> Plachonia careya </em>and <em>Terminalia cattappa</em>, had disproportionately higher levels of <em>D. krausii </em>parasitism than would be expected based on the proportion of different infested fruit species sampled, or levels of fruit fly infestation within those fruit.</p>