LETHAL AND SUBLETHAL EFFECTS OF PYRROLIZIDINE ALKALOIDS ISOLATED FROM Senecio rubdeckiaefolius ON PEST CONTROL OF Oryzaephilus surinamensis

SAMANTA KATHERINA GONZÁLEZ; MARÍA TERESA AJMAT; SUSANA BEATRIZ POPICH; MARIANA PEROTTI; SCHUFF CAROLA

Tafí del Valle

Jornada; XXXIV ANNUAL SCIENTIFIC MEETING OF THE TUCUMAN BIOLOGY ASSOCIATION; 2017

Asociación de Biología de Tucumán

Oryzaephilus surinamensis is a beetle which often infests walnut warehouses of small-scale farmers in the provinces of La Rioja andCatamarca, becoming a serious phytosanitary problem. The use of secondary metabolites obtained from plants as possible biopesticides hasaroused great interest due to its low impact on ecosystems. The aim of this paper was to analyse the lethal and sublethal effects ofpyrrolizidine alkaloids (AP) isolated from a methanolic extract of S. rudbeckiaefolius on O. surinamensis larvae. Repellency and toxicityassays were carried out on larvae fed on walnuts impregnated with 10% water-alcohol solution of AP (100, 150, 200 and 250mg/L) as wellas on unimpregnated walnuts as control. 3 repetitions were carried out and sublethal effects were checked until pupal formation. Theproduct did not turn out to be repellent at the assayed concentrations. Mortality percentages were dependent on concentration levels; withextracts at 200 and 250 mg/L the mortality rates were 70% and 77% respectively. The surviving larvae exhibited sublethal effects such asmalformation and coloration changes. The larvae exposed to lower concentrations exhibited low mortality rates and the surviving larvaedid not develop fully. These results show the capacity of S. rudbeckiaefolius AP as a pesticide and for growth-impairment on O.Surinamensis larvae.