EFFECT OF EAR WOUNDING AND CULTURAL-PRACTICES ON ABUNDANCE OF CARPOPHILUS-FREEMANI (COLEOPTERA, NITIDULIDAE) AND OTHER MICROLEOPTERANS IN MAIZE IN NORTHEASTERN MEXICO

Field experiments were conducted from 1993 to 1997 in northern Tamauli pas, Mexico, to identify the sap beetles and other microcoleopterans a ttracted to maize ears, and to evaluate their abundance in relationshi p to growing season (spring or fall), ear wounding (caterpillars, bird s, and artificial), crop phenology, cultivar, and aflatoxin contaminat ion. During the 5-yr study, 14 species of microcoleopterans in 7 famil ies were identified. However, only 3 of these species comprised 97% of the total captures: Carpophilus freemani Dobson (Nitidulidae), Cathar tus quadricollis (Guerin-Meneville) (Cucujidae), and Sitophilus zeamai s Motschulsky (Curculionidae). C. freemani was by far the predominant species, comprising nearly 90% of all collections regardless of growin g season, crop management, or type of ear damage. Sap beetles occurred commonly during both the spring and fall growing seasons. Compared wi th undamaged ears, microcoleopterans were 2- to 5-fold more abundant i n caterpillar-damaged ears, and 5- to 28-fold more abundant in bird-da maged and artificially damaged ears. C. freemani seemed to respond mor e to ear wounding (5- to 10-fold) than C. quadricollis and S. zeamais (2- to 4-fold). A maximum average density of 57 sap beetles per ear wa s observed in artificially damaged ears during the spring of 1993. Max imum abundance of microcoleopterans occurred from dough-hard to 25% ke rnel moisture stages. C, freemani was abundant during all maize reprod uctive stages, whereas C, quadricollis and S, zeamais were common only when kernels were drying down (15-20% moisture). Number of sap beetle s varied significantly among cultivars in both undamaged and damaged e ars. Infection by Aspergillus-flavus Link:Fr and aflatoxin contaminati on of maize were enhanced by ear wounding and incidence of sep beetles .