INCIDENCE, POPULATION FLUCTUATION AND SEVERITY PERCENTAGE OF Scyphophorus acupunctatus IN MAGUEY PULQUERO IN NORTHEASTERN STATE OF MEXICO

Abstract

The agave weevil Scyphophorus acupunctatus Gyllenhal is the most severe and important pest in commercial species of the genus Agave. The objective of this study was to evaluate the incidence (IN), population fluctuation (PF) and severity percentage (SV) of S. acupunctatus in three commercial plantations with different varieties of maguey pulquero, Agave salmiana Otto ex Salm-Dyck, in Northeast State of Mexico, Mexico. The IN was calculated by simple random sampling by quadrants; PF was obtained through a biweekly count and sexation of S. acupunctatus and a linear regression was used to determine the possible relation between relative humidity (RH) and temperature (T) with PF of S. acupunctatus. The percentage of SV was measured with a diagrammatic scale of severity and evaluated with the Kruskal Wallis test and Bonferroni correction. The severity per variety was estimated using the data obtained from observed severity plus the addition of agroecosystem assessment, which was obtained from the calculation of the agroecological plot index (IPA) and phytochemical characterization by variety (CR). The IN of S. acupunctatus ranged from 2 to 49 % in plants; the three plantations showed a female to male ratio with a tendency to 1:1, and although there was an increase of S. acupunctatus in the months of May-June and October-November, there was no significant influence of RH and T on PF of S. acupunctatus. The degree of SV was related to the varieties (P = 2.6 E-12). Variety Verde had higher SV compared to Manso (P = 1.5 E-7) and Carrizo (P = 8.4 E-11). CR % protein and % fat showed significant correlation (P < 0.01) with SV. Adults of S. acupunctatus can be found throughout the year in the maguey pulquero plantations evaluated, with an incidence of infested plants up to 50 %. Varieties of maguey pulquero behaved differently, being Verde the one with the highest SV.