The Influence of Maternal Age, and Rearing Density Upon Flight Activity of the Green Rice Leafhopper, Nephotettix cincticeps Uhler (Hemiptera: Deltocephalidae)

Abstract

In the green rice leafhopper, Nephotettix cincticeps, flight ability of adults in relation to the number of days that elapsed after their emergence (Expt. I), the influence of maternal age (Expt. II), and of rearing density (Expt. III) upon flight activity of adults were studied by tethered flight experiments. The insects used in Expt. I had been reared at 25°C, under 24 hr illumination, while those in Expts. II and III, were reared at 30°C, under 16 hr illumination. The tethered flight experiment was conducted at a temperature of 30°C with a headwind of 1-2m/sec. From the 2nd day after emergence in the case of the female and 4th day in the male, the adults began to fly, and on about the 8th day, which was 1 or 2 days before oviposition (the mean pre-oviposition period was 9.7 days), the flight duration and percentage of adults which flew attained their maxima. Differences between “fly” and “non-fly” adults in their flight activity and in the physiological characteristics were compared with each other among the progeny derived from different ages of famale adults: 1st to 3rd (young mother), 6th to 8th (middleaged mother) and later than 11th (old mother) day after the beginning of oviposition. In the offspring derived from young mothers, the “fly” adults had inferior physiological characteristics, e.g. shorter life span of adult, longer preoviposition period, and lesser number of eggs deposited, compared with those of the “non-fly,” but these relationships were reversed for offspring from old mothers. These facts suggested that there existed a tendency of specialization of migrants and residents among offsprings produced from young mothers, and that only vigorous individuals are able to fly among those from old mothers. Flight activity was compared between adults which had been reared as nymphs at a high population density (5 larvae/tube) and isolated. The former had high flight activity and inferior physiological characteristics compared with the latter. This suggested that the high larval population density urges the specialization of migrants and residents. In this respect, population density during adulthood was ineffective. © 1972, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.