title: Larval competition between Aphidius ervi and Praon volucre (Hymenoptera: Braconidae: Aphidiinae) in Macrosiphum euphorbiae (Hemiptera: Aphididae).
abstract: Interspecific competition between parasitoid larvae may influence the size, structure, and stability of the population, leading to a reduction in total parasitism and thus restricting the pest control. Aphidius ervi (Haliday) and Praon volucre (Haliday) are endoparasitoids that possess  a wide host range and present considerable potential for the biological control of the aphid Macrosiphum euphorbiae (Thomas). The larval competition between A. ervi and P. volucre, and the possible intrinsic competitive superiority of one of the parasitoids in M. euphorbiae, have been studied.  In single parasitism experiments, mated parasitoid females (n=10) were maintained individually in contact with M. euphorbiae hosts (n=30) inside petri dishes containing lettuce leaf discs and maintained in environmental chamber at 22 ± 1°C, 70 ± 10% RH, and  12-h photophase. The multiple parasitism experiments consisted of exposing single parasitized aphids (n=120) to the second parasitoid species. Two oviposition events were performed with a 4-h interval between them, namely the following: sequence A (oviposition by A. ervi, followed by  P. volucre) and sequence B (oviposition by P. volucre, followed by A. ervi). Oviposition sequence A generated 24 A. ervi and 55 P. volucre adults, whereas oviposition sequence B generated 23 and 49 adults. P. volucre is an intrinsically superior competitor compared with A. ervi, and the use  of the two species simultaneously may result in competitive exclusion and influence the stability of the parasitoid population.
authors.affiliation: Departamento de Entomologia, Universidade Federal de Lavras, 37200-000, Lavras, MG, Brazil.
authors.forename: Lívia Alvarenga
authors.initials: LA
authors.lastname: Sidney
authors.forename: Vanda Helena Paes
authors.initials: VH
authors.lastname: Bueno
authors.forename: Juracy Caldeira
authors.initials: JC
authors.lastname: Lins
authors.forename: Marcus Vinicius
authors.initials: MV
authors.lastname: Sampaio
authors.forename: Diego Bastos
authors.initials: DB
authors.lastname: Silva
mesh_terms: D000818:Animals; D001042:Aphids / Q000254:growth & development / Q000469:parasitology*; D003163:Competitive Behavior; D005260:Female; D007814:Larva / Q000254:growth & development / Q000502:physiology; D009758:Nymph / Q000254:growth & development / Q000469:parasitology; D010572:Pest Control, Biological; D011156:Population Density; D014863:Wasps / Q000254:growth & development / Q000502:physiology*