Oviposition behavior in non-irradiated and irradiated melon fly, Dacus cucurbitae COQUILLETT, was studiedunder laboratory conditions. A few irradiated female melon flies inserted their ovipositors into slices of host fruits (melon and watermelon) and artificial oviposition devices. The quantity and frequency of ovipositional “acts” for irradiated flies was much lower than that of the non-irradiated ones. “Number” indicates the quantity of females which engaged in oviposition behavior per 1, 000 females per 15min. “Frequency” indicates the total number of acts in varying behavioral modes per 1, 000 females per 15min.
Effective radius of the tow net used for the collection of migrating insects on the East China Sea was measured at various wind speeds generated by a wind tunnel. A linear equation Y=69.4+1.22X was obtained in which Y indicates the collecting efficiency (%) transformed from the effective radius and X the wind speed (m/s) in a range of wind speeds of 4.9m/s to 13.1m/s. Aerial densities per 103m3 of the whitebacked planthopper, Sogatella furcifera HORVÁTH, the brown planthopper, Nilaparvata lugens STÅL and the small brown planthopper, Laodelphax striatellus FALLÉN, were estimated based on surveys conducted in 1977, 1979 and 1980 on the East China Sea.
To establish the method for transportation of sterilized adults of the melon fly, Dacus cucurbitae COQUILLETT, recovery speed of adult flies anesthetized by chilling and various gases were investigated. Adult flies anesthetized by chilling recovered in a short time after transfer to normal temperatures, regardless of duration chilling period. A much longer time was needed for recovery from anesthetization with CO2 and N2, depending on the period of exposure. The flight ability of adults anesthetized with CO2 gas was retarded more severely than that of adults which were anesthetized with N2 gas or chilled.