Chromosomal studies in three species of the genus dacus (Trypetidae: Diptera)

Abstract

Somatic chromosomes and Giemsa C-banding patterns of three species of fruit flies belonging to the genus Dacus, viz., D. cucurbitae, D. zonatus and D. diversus are described. There are five pairs of long, euchromatic autosomes and one pair of smaller sex chromosomes which are homomorphic in females (XX) and heteromorphic in males (XY). In all the species the Y chromosome is in the form of a dot while the X chromosome varies in morphology. The autosomes of D. cucurbitae and D. zonatus are characterized by distinct C-bands, however, the C-bands are not very clear in 1). diversus. Y chromosomes in all the species are C-band positive. The X chromosomes of D. cucurbitae and D. diversus are C-band positive but those of D. zonatus show only a small interstitial band.orchards and fields and brought to the laboratory to obtain larvae and pupae of D. zonatus, D. cucurbitae and D. diversus, respectively. Stocks were maintained in the laboratory at 26-28°C. Adults were fed on enzymatic yeast hydrolysate (N.B.C.) and sugar solution. Pieces of pumpkin were provided for oviposition and larvae allowed to grow on the same for 4-5 days. For pupation sand was provided and when pupation was complete, pupae were collected from the sand and transferred to insect rearing cages in petri dishes to maintain the next generation. The cytological techniques used were identical to those reported by Kaul et al. (1978). Observations

Studies on mitotic and salivary chromosomes of Dacus cucurbitae Coquillett (Diptera: Trypetidae)

“…Our findings are much closer to those of Bhatnagar et al (1980) than to those of Gopalan (1972). A slight difference in the interpretation of metacentric and submetacentric chromosomes exists which may be due to technical variations, because Bhatnagar et al (1980) used the squash method.…”

“…For instance, the karyotype reported by Gopalan (t972) consists of three pairs of metacentric and two pairs of acrocentric autosomes and a slightly heteromorphic acrocentric pair represcnting the sex chromosomes, while Bhatnagar et al (1980) reported again a different karyotype for this species, with one pair of submetacentric and five pairs of metacentric chromosomes including the X chromosomes, the Y being dot-like in the male (Fig. 2).…”

“…A slight difference in the interpretation of metacentric and submetacentric chromosomes exists which may be due to technical variations, because Bhatnagar et al (1980) used the squash method. However, the possibility that there exist two chromosomal races can not be rulcd out.…”

“…Recently Dacus cucurbitae, a serious pest of more than eighty types ot" fruits and vegetables has been analysed cytogenetically in lndia (Srivastava & Kaul, 1961;Gopalan, 1972;Gopalan & Dass, 5972;Bhatnagar et al, 1980). Unfortunately the outcome of these studies has been the point of controversy.…”

Cytogenetic analysis of the Ethiopian fruit fly Dacus ciliatus (Diptera: Tephritidae)

“…This study is to our knowledge the first contribution to cytogenetics of the genus Dacus, as it is defined today. Previous chromosomal descriptions of Dacus species are referred to D. oleae (Gmelin), D. cucurbitae, D. zonatus and D. diversus (Krimbas 1963;Gopalan 1972;Bhatnagar et al 1980;Singh and Gupta 1984;Mavragani-Tsipidou et al 1992), which were recently assigned to the genus Bactrocera (Drew 1989). D. ciliatus has the same number of chromosomes (2n = 12) found in the mitotic metaphase complement of most tephritids (Fig.…”