Oviposition Patterns and Egg Mortality inAcanthoscelides macrophthalmus(Chrysomelidae: Bruchinae), a Biological Control Agent ofLeucaena leucocephala(Fabaceae) in South Africa

Abstract

Deliberately introduced for agroforestry, the invasive tree Leucaena leucocephala (Lam.) de Wit (Fabaceae) is naturalized in several countries worldwide, including parts of South Africa. The seed beetle Acanthoscelides macrophthalmus (Schaeffer) (Chrysomelidae: Bruchinae) was inadvertently introduced to several countries via contaminated seed, but was released as a biological control agent in South Africa. Although widely established in South Africa, its efficacy may be curtailed because damage is reputed to be confined to canopy-held seeds, with dehisced seeds escaping damage on the ground. To clarify the beetle's potential, we investigated: (i) its selection of oviposition sites when presented with pods bearing seeds, loose seeds and empty pods in different locations (canopy-versus ground-held); and (ii) the effect of seed location on egg mortality. The beetles oviposited on pods bearing seeds, loose seeds and empty pods in both locations but showed significant preferences for pods bearing seeds, regard...