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The gray pineapple mealybug, Dysmicoccus neobrevipes Beardsley, is an invasive pest that during recent years has caused serious damage on Sisal ( Agave sisalana Perrine) crops in South China. The biology of D. neobrevipes including its development, survivorship, longevity and reproduction was investigated at six constant temperatures (17, 20, 23, 26, 29 and 32 °C) under laboratory conditions. Results indicated that the developmental periods of D. neobrevipes females (from the first instar nymph to adult) shortened from 55.4 days at 17 °C to 16.9 days at 29 °C, while the males' decreased from 54.0 days at 17 °C to 15.8 days at 32 °C. The highest survivorship of D. neobrevipes from the first instar nymph to adult was recorded at 29 °C; 88.8% for females and 89.2% for males. The average longevity of females was 95.0 days at 17 °C, but decreased to 30.0 days at 26 °C. This was still significantly longer than those of males; 5.6 days at 17 °C and 2.3 days at 32 °C. The average number of nymphs laid per female increased with increasing temperature and reached a maximum of 409.4 nymphs at 23 °C. The intrinsic rates of increase ( r m ) of D. neobrevipes at the range of temperatures between 17 and 32 °C were 0.0287, 0.0613, 0.0941, 0.1131, 0.1202 and 0.0485, respectively. The lower temperature thresholds for females and males of D. neobrevipes from the 1st instar nymph to adult estimated using the linear model were 8.7 and 10.3 °C, respectively. The thermal constants for females and males were 370.4 and 312.5DD, respectively. The results indicate that temperature has significant effects on the biology of D. neobrevipes and that the optimum temperature range for its population growth is 23–29 °C. |
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