Population Dynamics of Pests and Natural Enemies on Sugar Cane Grown in a Subtropical Region of Brazil

Sugar cane production in the subtropical area of southern Brazil displays a different profile of growing conditions compared to other regions, and the population dynamics of both insect pests and their natural enemies are poorly documented. Monthly surveys were conducted in a subtropical sugar cane production area (29.003467°S, 53.235349°W) of Brazil. Samples were collected in a 15 ha field from Feb 2013 to Jan 2015, and the insects found on plants and inside culms were tabulated. The sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae) was found during all stages of plant development. These borers were most abundant during the cooler mo, when they reached a high level of infestation. The sugarcane mealybug, Saccharicoccus sacchari (Cockerell) (Hemiptera: Pseudococcidae), was found during most mo, but infestation levels were highest in Mar. The pink spittlebug, Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae), and sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), were found mostly in warmer mo, and associated with higher accumulations of rainfall. The infestations by M. fimbriolata were below levels of economic damage, whereas M. sacchari infested up to 100% of the plants. The natural enemies observed were the parasitoid Billaea claripalpis (Wulp) (Diptera: Tachninidae) and the predators Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) and Doru lineare (Eschscholtz) (Dermaptera: Forficulidae). Their population dynamics clearly showed host/prey dependence. These results contribute to the monitoring and management strategies of pests in sugar cane grown in the subtropical conditions of southern Brazil.