Population fluctuations of immature stages of the citrus flower moth, Prays citri Mill. (Lep.: Hyponomeutidae) on lime trees

Abstract

Mean numbers of immature stages of Prays citri Mill. on lime flower buds showed six annual population peaks of 13.3, 1.2, 1.8, 6.2, 2.8 and 3.4 in mid-May, mid-Oct., mid-Nov., mid-Dec., mid-Feb. and mid-Mar., respectively during 2015/2016 season. Five peaks of 13.5, 14.5, 1.8, 5.8 and 5.0 immature stages were observed on flowers in mid-Apr., mid-June, mid-Oct., mid-Dec. and mid-Mar., respectively. On newly formed fruits, five peaks of 7.3, 0.4, 2.2, 1.8 and 2.4 immature stages were also recorded in the middle of June, Oct., Dec., Feb. and Mar., respectively. The general mean was the highest (11.3 immature stages) in June, while it was the lowest (0.0 immature stage) in Sep. The highest population density of P. citri was recorded in spring, followed by summer then winter and autumn. The seasonal mean was 4.1 immature stages in 2015/2016 season. The same trend could be applied during 2016/2017 season. Six peaks of 12.8, 2.5, 4.0, 5.8, 3.3 and 4.6 immature stages were estimated on lime flower buds in mid-May, mid-Oct., mid-Nov., mid-Dec., mid-Feb. and mid-Mar., respectively. Mean numbers of P. citri immature stages on flowers also exhibited six peaks of 14.5, 2.8, 5.3, 7.2, 4.3 and 5.6 in mid-Apr., mid-Oct., mid-Nov., mid-Dec., mid-Feb. and mid-Mar., respectively. Six peaks of 5.8, 1.0, 1.8, 3.0, 1.5 and 2.4 immature stages were also found on newly formed fruits in the middle of May, Oct., Nov., Dec., Feb. and Mar., respectively. The highest general mean was 10.8 immature stages in May, while the lowest was 0.0 immature stage in Sep. The highest population density of P. citri occurred in spring, followed by summer then winter and autumn. The seasonal mean was 4.6 immature stages in the second season.