Impact of the Parasitoids Anisopteromalus calandrae (Howard) and Lariophagus distinguendus (Förster) on Three Pests of Stored Rice

SIMPLE SUMMARY: Various pest species cause significant damage to stored rice, and polyphagous parasitoids could offer an appropriate biological control strategy. Among the beneficial species colonising silos and warehouses of rice, the generalist pteromalid parasitoids Anisopteromalus calandrae and Lariophagus distinguendus have been found to be prevalent in samples collected in the northeast of Spain. In this study, the Spanish strains of both parasitoids have shown that they may play important roles in controlling three coleopteran pests of stored rice: Sitophilus oryzae, Rhyzopertha dominica and Lasioderma serricorne. They reduced the number of pests that emerged due to effective parasitism (parasitoids reaching the adult stage and emerging from the grain), combined with other sources of host mortality, such as parasitoid immature mortality and parasitoid host feeding. Both parasitoids preferentially attack S. oryzae, which is a key pest of stored rice, but they also play an important role in the control of R. dominica, a less important pest. Although both parasitoids could consume L. serricorne larvae, their efficacy is low, and more specific natural enemies should be evaluated for the control of this pest. ABSTRACT: This study evaluated the ability of pteromalid parasitoids Anisopteromalus calandrae and Lariophagus distinguendus reared on Sitophilus zeamais to control stored product coleopteran pests Sitophilus oryzae, Rhyzopertha dominica and Lasioderma serricorne. In trials of parasitoid treatment with A. calandrae, fewer pests (S. oryzae and R. dominica) emerged than in the control. Parasitoid reproduction was highest with S. oryzae as a host, followed by R. dominica and L. serricorne. In trials of parasitoid treatment with L. distinguendus, fewer pests (S. oryzae, R. dominica and L. serricorne) emerged than in the control treatment. Sitophilus oryzae was the host with the highest rate of parasitoid reproduction, although the greatest level of reduction was seen in R. dominica (i.e., host feeding levels were higher for this host species). For L. serricorne, no L. distinguendus progeny was produced. For both species, parasitoids with significantly longer bodies and tibiae emerged from S. oryzae. These results suggest that both parasitoids have potential for use as biocontrol agents for different coleopteran species that attack stored rice.