Thermal requirements and estimated number of generations of Neopamera bilobata (Say) in strawberry-producing regions of Brazil

ABSTRACT: The thermal threshold and thermal requirements of Neopamera bilobata were determined, and the number of generations that this species may produce in the main strawberry-producing regions of Brazil was estimated. In a climate chamber (70±10% RH and 12h photophase) at 16, 19, 22, 25, 28, or 30±1°C, the development of 120 eggs was monitored until the adult stage, at each temperature. Nymphs were maintained in individual cages and fed on strawberry fruits of the cultivar Aromas. The mean duration and viability of the egg and nymph stages were calculated by estimating the lower and upper developmental thresholds and the thermal constant, and this information was used to estimate the number of generations per year in different strawberry-producing regions of Brazil. The egg-to-adult duration decreased as temperatures increased, up to 28°C (93.4, 83.2, 43.9, and 31.4 days at 19, 22, 25, and 28°C, respectively). Viability of nymphs was highest between 22 and 28°C. At 30°C, the egg-to-adult duration increased (36 days), while the viability decreased (11.11%). The lower egg-to-adult developmental threshold was 15.2°C and the thermal constant was 418.4 degree-days. Calculating the number of generations indicated that the largest number (5.1 generations yr-1) was obtained for the municipality of Jaboti, Paraná, and the smallest for Caxias do Sul, Rio Grande do Sul (1.9 generations yr-1). Our findings demonstrated that important strawberry-producing regions in Brazil are suitable for the development of N. bilobata.

摘要：本研究明确了双斑新长蝽（Neopamera bilobata）的发育阈值与热需量，并估算了该物种在巴西主要草莓产区的年发生代数。实验在温度设置为16、19、22、25、28或30±1℃的人工气候箱（相对湿度70±10%，光照时长12h）中开展，对各温度下的120枚卵直至成虫的发育进程进行监测。若虫均单独饲养于养虫笼中，以‘芳香’（Aromas）品种草莓果实为食。通过估算发育起点温度、发育上限温度与热常数（thermal constant），计算得到卵期和若虫期的平均发育时长与存活率，并利用该结果估算巴西不同草莓产区该物种的年发生代数。卵至成虫的发育时长随温度升高而缩短，在28℃时达到最短：19、22、25和28℃下分别为93.4、83.2、43.9和31.4天。若虫存活率在22~28℃区间内达到最高。在30℃条件下，卵至成虫的发育时长反而增至36天，存活率则下降至11.11%。卵至成虫的发育起点温度为15.2℃，热常数为418.4日度（degree-days）。通过年发生代数计算可知，巴拉那州雅博蒂市的年发生代数最多，达5.1代/年；南里奥格兰德州卡希亚斯杜苏市的年发生代数最少，仅1.9代/年。本研究结果表明，巴西多个重要草莓产区均适于双斑新长蝽的生长发育。