Abordagens uni e multidimensionais para compreensão da dinâmica de infestação de Diatraea impersonatella em variedades de cana-de-açúcar em sistemas irrigado e sequeiro

Abstract

Sugarcane is highly relevant for neotropical agribusiness, with Brazil being the world's largest producer and exporter of sugar. However, crop productivity and quality are threatened by infestation of lepidoborers of the Diatraea complex, such as the species Diatraea impersonatella (Walker, 1863) (Lepidoptera: Crambidae), which causes significant losses in the sugarcane agroindustry. Therefore, this study aimed to evaluate, from both univariate and multivariate perspectives, whether the dynamics of D. impersonatella infestation are influenced by sugarcane varieties, plant age, cultivation conditions, and distance from the carrier. For this purpose, the insect infestation levels were analyzed in the following varieties: RB 92-579, RB 04-1443 and RB 86-7515, at ages of 45, 70, 130 and 200 days after planting, in two conditions of dry and irrigated planting and distance from the carrier of 0, 10, 30 and 90 meters. The research was conducted in five municipalities in the state of Paraíba, where the number of bored stalks per plot and agro-industrial variables were quantified. Plants aged 45 days were evaluated based on the observation of wilting symptoms on the main leaf (dead heart) and subsequently subjected to opening to detect the pest. Plants aged 70, 130, and 200 days were subjected to straw removal and checked for the presence of borer entry holes. Based on the results obtained, it was observed that all varieties tested were infested by the borer, with the RB 92-579 variety showing greater susceptibility. A positive unidirectional relationship was observed involving the incidence of attack with the age of the plant, where the incidence of D. impersonatella was already observed from 45 days after planting. Among the cultivation systems, a greater infestation was observed in the irrigated system, a fact validated by the adopted multidimensional scaling. For the distance from the carrier, it was observed that the presence of the pest increased with proximity to the carrier. The univariate and multivariate findings revealed bioecological information fundamental for the management of D. impersonatella, indicating that control measures should consider the age of the plants, the cultivated variety, the cultivation system, and the distance from the carrier.