Comparative evaluation of the infestation of five varieties of citrus by the larvae of <i>Anastrepha ludens</i> (Diptera: Tephritidae)

Abstract Anastrepha ludens Loew (Diptera: Tephritidae) is a pest of fruits that is attracted by the volatile compounds that emanate from fruit. In citrus (Sapindales: Rutaceae), this pest primarily feeds on the pulp and develops inside orange ( Citrus x sinensis (L.) Osbeck) and grapefruit ( Citrus x paradisi Macfad.) fruits, which cause substantial economic losses. The degree of infestation by citrus variety is still unknown, and determining these levels would be ideal to optimize the strategies for phytosanitary control. The objective of this study was to quantify and compare the level of infestation of A . ludens larvae in bitter orange ( Citrus x aurantium L.), navel orange ( C. x sinensis ‘Naval orange’), early orange ( C. x sinensis ‘Marr’s Early), Valencia orange ( C. x sinensis ‘Valencia’) and red grapefruit ( C. x paradisi ‘Red blush’). The study was conducted from August 2018 to July 2019 in the municipalities of Gómez Farías, Güémez, Hidalgo, Llera de Canales and Victoria, Tamaulipas, Mexico. In these municipalities, larval instars of A . ludens were sampled by collecting eight to 15 fruits hanging from the tree or lying on the ground; fruits were collected with yellow or necrotizing circular spots and signs of premature maturation. The infestations of A . ludens larvae among the five varieties were quantified by a multivariate analysis of variance and discriminant function analysis. Our results showed that the number of second instar larvae per fruit was responsible for the variation (separation between varieties), and they prefer bitter orange compared to the other four varieties of citrus that were analyzed. The information from this study will enable stakeholders to direct strategies of phytosanitary control toward the bitter orange crop, a preferred host of this pest in the citrus growing region of Tamaulipas, Mexico.