Can the use of particle films for fruit protection against medfly alter the behavior of the parasitoid Diachasmimorpha longicaudata?

The use of particle films, especially kaolin-based films, is a promising technology to control infestations of Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), an important pest of fruits. However, its effects on one of the most important biocontrol agents of this fly in Brazil, the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae), are unknown. This study aimed to evaluate the influence of mineral particle films on the oviposition behavior of D. longicaudata and to determine the success of parasitism in C. capitata using grape (Vitis vinifera L., Vitaceae) as substrate. Before the bioassays, the color characteristics, firmness, total soluble solid content, pH, and titratable acidity of the fruits were determined. Grapes were immersed in suspensions of kaolin Surround WP, kaolin 607, kaolin 608, and distilled water (control); thereafter, they were perforated, and two C. capitata third instars were inserted into the orifice. The grapes were then exposed to a female parasitoid. The frequency and duration of the following behavioral parameters of D. longicaudata were evaluated: landing on fruit, inspection, buccal contact, oviposition, cleaning, resting on fruit, and resting on cage. Furthermore, parasitism success was assessed. Mineral particle films altered the color and firmness of the grapes. The females of D. longicaudata performed all distinguished behaviors in treated and untreated grapes, except buccal contact, which was not done on the kaolin-treated fruits. Kaolin 607 negatively affected landing, inspection, puncture, and rest behaviors; kaolin Surround WP only reduced inspection and puncture. Fruit coating with all three tested kaolin products decreased the success of parasitism of D. longicaudata, indicating that particle films applied to plant organs can affect the behavior of this natural enemy.