Sexual competitiveness of sterile males of Ceratitis capitata from a tsl strain exposed to different essential oils of native species of Argentina in field cage experiments

FLAVIA JOFRÉ-BARUD; M. PÍA GÓMEZ; GUILLERMO BACHAMNN; M. JOSEFINA RUIZ; DIEGO SEGURA; NATALIA LARA; FERNANDO MURÚA; OSVALDO LARIA; ÉRICA GÓMEZ BARRIONUEVO; ANDREA BARTOLUCCI; CYNTHIA RUIZ; M. TERESA VERA; M. LIZA LÓPEZ

Simposio; International symposium of fruit Flies of Economic importance; 2018

Background: The Sterile Insect Technique is used throughout the world to reduce the populations of fruit flies of economic impact. Among the actions taken to improve the sexual competitiveness of sterile males of the Mediterranean fruit fly, Ceratitis capitata, is the exposure to plant-derived volatiles. The exposure to the essential oil of the ginger root (GRO) is one of the most studied cases and has been implemented in the field. The aim of this study was to advance in the knowledge of the effect of the exposure of the essential oil volatiles from different native species of Argentina on the sexual competitiveness of sterile males from one genetic sexing strain of C. capitata males as a part of a joint project between the National Fruit Fly Control and Eradication Program and Research Institutions.  Methods: Sterile males came from the mass rearing facility of San Juan Province, Argentina, and wild material was collected from infested fruit in the province of San Juan. Field cage tests were performed following the Quality Control Manual from FAO/IAEA/USDA. Four days old tsl males were exposed to one of the following essential oils Baccharis spartioides, Schinus polygama, S. areira, and Zingiber officinale (GRO), which acted as reference. In addition, for GRO and S. areira, two ratios of sugar ? hydrolyzed yeast in the sterile males diet were evaluated: 12:1 and 3:1. Number of mating pairs, latency to mate, location where mating pairs occurred inside the field cages and copula duration were recorded. The Relative Sterility Index (RSI) was estimated and compared between the different exposure treatments.Results: Not all oils produce the same level of male competitiveness enhancement. Males performed better when exposed to the oils of S. polygama and GRO, followed by B. spartioides. Males exposed to the essential oil of S. areira showed a lower competitiveness than unexposed males. Most of the couples were collected from the underside part of the leaf of the tree or the upper part of the field cage. Sterile males mating competitiveness was not affected by the diet. Exposure treatment had no effect on mating latency and there were also no differences between sterile and wild males for this variable. Exposed males and wild males had the same copula duration. Unexposed sterile males presented a lower value.Conclusions: The essential oils of two native plants as well as GRO improved the sexual performance of tsl sterile males compared to unexposed males. In particular, males exposed to the volatiles of S. polygama essential oil presented the best performance. These results prompt the evaluation of exposures at a large scale and encourage the implementation of exposure treatments before sterile males release.