Isolation, identification, synthesis and field evaluation of the sex pheromone from the citrus leafminer, Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae)

by Parra-Pedrazzoli, Ana Lia

The objectives of this work were to isolate, identify, and synthesize the sex pheromone of Phyllocnistis citrella Stainton, 1856 (Lepidoptera: Gracillariidae), as well as to evaluate its efficiency in field conditions, to rationalize the control of this pest within a Citrus Integrated Pest Management scope. The research was developed at the Insect of Biology Laboratory, of the Department of Entomology, Plant Pathology and Agricultural Zoology of the Escola Superior de Agricultura ?Luiz de Queiroz? (ESALQ), Piracicaba, University of Sao Paulo (USP), at Maeda-Duffey Laboratory, of the Department of Entomology of the Universityof California, Davis (UCD-USA), and at the United States Department of Agriculture, (USDA, Peoria, USA). Pheromone glands from groups of 200 two-day-old virgin females were excised within 2 h, starting 1 h before the photophase. The abdominal tips were immersed in hexane for ca. 1 h. A total of 5,000 glands-equivalent was pooled, the extract was transferred to glass ampoules, which were sealed, and shipped to Davis. Using male antenna as the sensing element, three EAD-active peaks were identified from gland extracts of P. citrella. Based on GC-MS and GC-IR data, the semiochemicals were identified as a novel pheromone, (Z,Z,E)- 7,11-13-hexadecatrienal, a previously identified attractant, (Z,Z)-7,11-hexadecadienal, and (Z)-7-hexadecenal in a ratio of 30:10:1, respectively. Identification was confirmed with synthetic compounds, which gave retention times identical to those of the natural products in three capillary columns with polar and non-polar phases. In field conditions, traps baited with the synthetic sex pheromone, attracted significantly more males than traps baited with virgin females. Binary and tertiary mixture with the major constituents in high and low concentrations did not differ significantly in the captures. Thus, it was confirmed that Z7Z11E13-16Ald e Z7Z11-16Ald are the essential constituents of the sex pheromone of P. citrella and they can be used on citrus crops for monitoring this pest, rationalizing and improving its control and maintaining the natural enemies in the environment.