Influence of Distance from the Host on Parasitisation by <i>Psyttalia concolor</i> (Szépligeti) (Hymenoptera: Braconidae)

• Main Authors: Nuray Baser, Gabriella Lo Verde, Gülay Kaçar, Flutura Lamaj, Vincenzo Verrastro, Alberto Lombardo, Francesco Tortorici, Virgilio Caleca
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Insects
• Subjects: olive fruit fly; medfly; laboratory host; ovipositor length; parasitoid rearing
• Online Access: https://www.mdpi.com/2075-4450/10/10/316

The olive fruit fly, <i>Bactrocera oleae</i>, is considered the main olive pest worldwide, and has been the target of biological control programmes through the release of the braconid parasitoid <i>Psyttalia concolor</i>. Laboratory tests were performed to evaluate the influence of distance from the host on parasitisation, placing larvae of the substitute host <i>Ceratitis capitata</i> at seven distances (0, 0.5, 1, 1.5, 2, 2.5, 3 mm) and four different time periods (7, 15, 30, 60 min). Moreover, field collected olives of Ogliarola Barese cultivar infested by <i>B. oleae</i> were exposed to <i>P. concolor</i> females to confirm its ability to parasitise <i>B. oleae</i> in small olives. <i>Psyttalia concolor</i> oviposition was inhibited at 2.5 and 3 mm due to the ovipositor length of the parasitoid females (2.7 mm). Hosts were easily parasitised at distances between 0 and 1.5 mm. The thin fruit pulp (up to 3.5 mm) of field collected olives allowed the parasitisation to occur also in mature fruits. At the best combination distance/time (0 mm, 30 min), tests performed with different larvae/parasitoid female ratio showed an increasing emergence of <i>P. concolor</i> (from 20% to 57%) with larvae/parasitoid ratio increasing from 0.11 to 0.74. The results of the present study might optimise the mass rearing of <i>P. concolor</i>, through a proper setting of its parameters, such as the host/parasitoid ratio, exposure distances, and interaction time.