Author(s): Abraços Duarte, Gonçalo ; Caldas, Filipa ; Pechirra, Ariadna ; Borges da Silva, Elsa ; Figueiredo, Elisabete
Date: 2021
Persistent ID: http://hdl.handle.net/10400.5/23327
Origin: Repositório da Universidade de Lisboa
Subject(s): biological control; competition; conservation; Macrolophus pygmaeus; Mediterranean crops; Nesidiocoris tenuis; protected crops; Hemiptera; Miridae; alternative prey; intraguild predation; cannibalism; tomato; Ephestia kuehniella; Dicyphus cerastii
Dicyphine mirids are one of themost important groups of predators on tomato. In theMediterranean region, several species in the genera Dicyphus, Macrolophus, and Nesidiocoris (Hemiptera: Miridae, Bryocorinae, Dicyphini) colonize protected horticultural crops. In Portugal, Nesidiocoris tenuis (Reuter) is increasingly abundant in the mirid species complex of tomato crops and appears to be displacing the native Dicyphus cerastii Wagner. In order to know whether intraguild predation (IGP) can explain the decreasing abundance of D. cerastii, we evaluated predatory interactions between adult females and first instars of D. cerastii vs. N. tenuis but also D. cerastii vs. Macrolophus pygmaeus (Rambur), as this species is also naturally present in horticultural crops in Portugal. Cannibalistic interactions were also tested for the same three species. All experiments were performed under laboratory conditions, in Petri dish arenas, in the presence or absence of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs as alternative prey. Predation on both heterospecific and conspecific nymphs occurred only in the absence of alternative food. Intraguild predation was mutual and symmetrical between D. cerastii andM. pygmaeus. However, IGP was asymmetrical between D. cerastii and N. tenuis, favouring the first. Cannibalism was not significantly different among these mirid species. Our results show that D. cerastii has a greater capacity to feed on intraguild prey than N. tenuis. Therefore, IGP on small nymphs does not explain the abundance shift between D. cerastii and N. tenuis
