Damage diagnostic of Sphenophorus incurrens Gyllenhal (Coleoptera: Curculionidae: Dryophthorinae), in sugar cane in México

In the last two years more than 500 ha of sugar cane have been affected by the presence of Sphenophorus incurrens (Gyllenhal), in Morelos and Michoacán, Mexico. The information about the presence of this insect in sugarcane in Mexico is not new but there is little information, so the present work was to determine the symptoms of their presence and some basic aspects of their biology to a better understanding of this pest. This data would help to establish measures for monitoring and management of sugar cane weevil populations. This insect is found throughout the year, but the population is most evident from January to April. At this time the damage can be evaluated in mature plants before go to the sugar mill through the number of stem dried or by the number of damaged stems and stumps remaining after cutting; they showed small holes (4-5 mm in diameter), which often exhibited orange coloration by microorganisms. In the following  production cycle, the field inspection of regrowth showed the shoots lack of emergency and in small plants appeared dry leaves, which eventually increased, finally the plant die, leaving small gaps in the plots. If not control treatment is applied the damage area grows. The cane sugar planting again is required to preserve the production. In both cases S. incurrens presence was confirmed by root extraction and damage in longitudinal sections of the stumps, and most of the time all the stages were found, larvae, pupa, and adults. The lasts ones are gregarious, skilled walkers with flight capability, so that the damage patterns and dispersion may be due to these behavioral characteristics.