Effect of Coleostephus myconis (L.) Rchb.f. and Echium plantagineum L.on longevity and fecundity of the olive moth, Prays oleae (Bern.)

Abstract: The use of flowering field strips is often proposed as a method to support biologicalcontrol in agro-ecosystems; however, the indiscriminate use of flowering species can lead tohigher pest numbers. The objective of this work was to study the effect of two naturally occurringplants in olive crops from northeast of Portugal, Coleostephus myconis (L.) Rchb.f. and Echiumplantagineum L., on adult longevity and fecundity of the olive moth Prays oleae (Bern.) fromlaboratory assays. The initial culture of olive moths started with larvae from antophagousgeneration collected from infested olive trees in Mirandela region (Trás-os-Montes, Portugal).Each larva was introduced in a tube (1.7cm diameter, 12cm high) till the emergence of adults.Newly emerged adult pairs were transferred into glass cages (7cm diameter, 9cm high) containinga small branch of olive tree in water and one of the following treatments. Blooming plants werealso collected in the olive groves and for each plant species, four different treatments wereintroduced in the cage and were tested: (A) a tube with 5ml of water, (B) an Eppendorf with 5%of honey in water (C) a flower in water and (D) a flower in water and 5% honey in water. Eachtreatment was composed by 30 replicates. Every 24 hours, male and/or female death and thenumber of eggs laid were counted. Results showed that both the olive moth longevity and numberof eggs were significantly higher in the treatments with water-honey solution (treatments B andD). The longevity of the olive moth reached an average of 13.6 days in treatment B as well as intreatment D for E. plantagineum. On the contrary, the longevity reached 6.4 and 7.5 days intreatment C for C. myconis and E. plantagineum, respectively. Considering fecundity, inE. plantagineum and honey, the olive moth laid an average of 40.7 eggs, followed by treatment Bwith 40.1 eggs and C. myconis and honey with 35.0 eggs. Considering the longevity of the olivemoth, there were no differences between the two plant species in all the treatments tested butfemale longevity tended to be higher than male longevity. These experiments suggested thatP. oleae benefited from sugar sources by increasing both longevity and fecundity. Nevertheless,the olive moth was not affected by the presence of C. myconis and E. plantagineum flowers.