Adult parasitoids need non-host food such as nectar or honeydew for survival and reproduction. In a conservation biological control strategy, the knowledge about non-host feeding of parasitoid species is a key factor to successfully increase their action. The nutritional behavior of Elasmus flabellatus (Fonscolombe) (Hymenoptera: Eulophidae), a major parasitoid of the olive moth, Prays oleae (Bernard) (Lepidoptera: Praydidae), is completely unknown. Survival experiments were performed on two secondary olive pest honeydews and eight common flowering plant species in order to analyze their suitability as potential food sources for E. flabellatus females. Abdomen and gut dissections were carried out to verify the pollen consumption and the egg production. Floral architecture and insect morphology were described. Cox’s proportional hazard regression models were used to analyze the differences between parasitoid survivals. Honeydews secreted by Saissetia oleae (Olivier) (Hemiptera: Coccidae) and Euphyllura olivina (Costa) (Hemiptera: Psyllidae) resulted in the best performance followed by the flowers of Malva sylvestris L. (Malvaceae), Daucus carota L. (Apiaceae), and the Cichorioideae Tolpis barbata (L.) and Andryala integrifolia L. Theoretical flower resources accessibility were assessed and related with the survival results. E. flabellatus females did not consume pollen and did not produce eggs, suggesting that the species is synovigenic and requires additional foods for egg production. In sustainable pest control programs, this novel knowledge is a prom ising opportunity for improving suitable food resources of E. flabellatus in the field.
Spontaneous ground covers comprise ecological infrastructures that may provide food, alternative hosts
and shelter for parasitoids in olive groves, thus contributing to biological control of pests. This study
investigated the effects of herbicide application, tillage, and conservation of spontaneous ground covers
on parasitism of the anthophagous generation of the olive moth, Prays oleae (Bernard). The study was
performed in northeast Portugal in 2011 and 2013 in 14 and 15 olive groves, respectively, with different
management types. Generalized Estimating Equations (GEE) were used to analyze olive moth emergence,
overall parasitism rate, relative abundance of parasitoid species, and total parasitismof olive moth larvae.
Ageniaspis fuscicollis (Dalman) accounted for the majority of the parasitism, followed by Elasmus flabellatus
(Fonscolombe). In both years, ground cover management type did not influence the emergence rate of
P. oleae. However, overall parasitism rate, emergence of A. fuscicollis, and the number of A. fuscicollis
emerging per olive moth larvae varied among years. In 2011, the latter response variables were significantly
higher in groves with spontaneous ground cover than in those treated with herbicide, indicating a
negative effect of herbicides on parasitoids. Although tilled groves obtained higher values for these
variables in 2013, parasitism rates were generally very low. In sum, the management of ground covers
seemed to influence the overall rate of P. oleae parasitism in some years, but longer-term experiments
are needed to clarify this trend.
