Celal Tuncer

SEX DISCRIMINATION OF ADULT CURCULIO NUCUM L. (COLEOPTERA: CURCULIONIDAE), A PEST OF HAZELNUTS IN TURKEY

The hazelnut weevil, Curculio nucum L., is the key pest of hazelnut (Corylus avellana L., Betulaceae) in many countries. Recently, increasing attention on the pest status of C. nucum in commercial orchards has accelerated the number of studies on its biology, behavior, and ecology (Ural, 1957; Tabamaishvili, 1988; Paparatti, 1990; Pucci, 1992; AliNiazee, 1997; 1998; Milenkovic and Mitrovic, 2001; Tuncer and Ecevit, 1997; Tuncer et al., 2001; Akça and Tuncer, 2005). At times, biological, behavioral, and ecological studies require researchers to determine the sex of adults without dissecting the genitalia and killing the organisms. Many earlier studies used the length of the rostrum in C. nucum as a criterion to distinguish their sex (Ural, 1957; Tabamaishvili, 1988; Sezen et al., 1999; Akça and Tuncer, 2005). In addition to this character, our previous study described several differences in average body size and elytral size between males and females in C. nucum. However, owing to large variation, sex discrimination using these characters, except rostral length, is not reliable. Rostral length is a good character to sex adult C. nucum [averaging 5.56 (4.926.65) and 3.96 (3.35-4.56) mm for female and male, respectively, differing significantly between sexes, t 0.05 (2), 49 = 30.2]; Akça and Tuncer, 2005). However, using rostral length is not convenient because it requires a device for measurement, and it appears to be affected by environmental factors. Also, the differences in rostral length can be as little as 0.5 mm, making it time-consuming and cumbersome to use, particularly for field applications (Akça and Tuncer, 2005). Duan et al. (1999) suggested the use of a suture dividing the last two abdominal tergites of males, instead of snout length, for sexing adult Anthonomus pomorum (Coleoptera: Curculionidae). Lykewise, Sappington and Spurgeon (2000) demonstrated that the tergal-notch in the eighth tergite of male Anthonomus grandis (Coleoptera: Curculionidae) is more accurate than snout characteristics for sexing the adults. This study describes a new, nondestructive character associated with abdominal tergites to discriminate male and female C. nucum adults. Volume 118, Number 1, January and February 2007 87

Sexual Dimorphism in the Pupal Stage of Hyphantria cunea (Lepidoptera: Erebidae)

ABSTRACT: Sexual discrimination of Hyphantria cunea Drury (Lepidoptera: Erebidae) is very easy through checking male and female antennae of adult moths. Often sexing of insects in pupal stages is also needed. Although weight and size of male and female pupae are quite different, these alone are not enough to distinguish the sexes in every instance. Examining pupae of H. cunea with a binocular microscope reveals differences between the male and female on the posterior ventral surface of the abdomen. The genital slit is located on the anterior edge of the 8th abdominal segment of the female while it is located in the mid-part of the 9th abdominal segment in the male, on the ventral surface. Also, the genital slit is about twofold longer in the female than in the male.