author(s)
Sowmiya L, Chandrasekaran M, Soundararajan RP and Ramesh D

abstract
The melon fruit fly, Zeugodacus cucurbitae (Diptera: Tephritidae), is considered as catastrophic pest in most of the cucurbitaceous vegetable crops. It is denoted as an economic pest and yield misfortune up to 50-70% depends upon the host's environmental condition and its weakness. During their entire life period, major portion they live inside the host. Matured females lay eggs in the skin of the host, and the cycle is continued. Only after completion of maggot stage, the pupa comes out from fruit to become an adult. For the better management of fruit fly, an investigation related with habitat based variation in its biology is a need. For this reason, the laboratory experiment was conducted at Department of Plant Protection, Anbil Dharmalingam Agricultural College and Research Institute, Tamil Nadu Agricultural University, Tiruchirappalli during November 2019 to January 2020. The biology and morphometry of different life stages of the melon fruit fly, Zeugodacus cucurbitae were carried out in snake gourd, bitter gourd, and ridge gourd host, at a temperature 25 ± 2^ºC and relative humidity 65 ± 5% to assess the variation in its life cycle. The results obtained in this laboratory experiment under a controlled atmosphere indicated that mean length and breadth of the egg (0.66±0.08 mm, 0.13±0.01 mm), first instar (1.10±008 mm, 0.19±0.01 mm), second in star (4.93±0.09 mm, 0.79±0.02 mm), third instar maggot (8.34±0.14 mm, 1.51±0.03 mm), prepupal (6.22±0.11 mm, 1.83±0.06 mm) and pupal period (5.69±0.38 mm, 2.05±0.08 mm) was maximum in bitter gourd host compared to snake gourd and ridge gourd. Similarly mean length and breadth of adult male (5.82±0.07 mm, 10.43±0.11 mm) and female (7.81±0.11 mm, 12.34±0.30 mm) was high in ridge gourd. On Comparing the other host, the egg period, first instar, second instar, third instar, prepupa, and pupal period was minimum in bitter gourd 1.45±0.76 days, 0.70±0.25 days, 2.85±0.74 days, 4.3±0.85 days, 0.80±0.25 days, and 8.25±0.82 days, respectively. The longevity of male and female flies was higher in ridge gourd host with 20.60±4.35 days and 21.40±3.20 days, respectively. The observation parameters registered on the biology of Z. cucurbitae in different cucurbitaceous hosts showed that the developmental duration was varied depends on host and adult longevity is maximum (20.60±4.35 days in male, 21.40±3.20 days in female) in ridge gourd.