| Bactrocera (Zeugodacus) tau (Walker) is a species of Bactrocera Macquart genus of the Tephritidae family and the Diptera order. It is one of the most important quarantine moth fruit pest insect. Overseas it mainly distributed in the Southeast Asia and South Pacific ocean region and domestic it mainly distributed in the South China and Southwest area. It also appeared in Wanzhou district, Beibei district etc., in Chongqing city. It mostly harmed melon vegetables and orange, mango etc. fruits. Female adult laid eggs under coat of novelty melon and fruit, and the larva hatched and ate in the fruit, which may led to fruit blet and less edible. By principle and method of insect population ecology, based on outdoor trials and indoor studies, the field population dynamic oiB.tau and the effect of development and propagation of B.tau under different temperatures and different supplementary nutrition were carried about in this paper. The main results are listed below.1 Studies on B. tau field population dynamic1.1 Studies on the quantity dynamic on different hosts and harm degree of B. tauBy field block investigation, the quantity dynamic of B. tau on cushaw, towel gourd, cucumber and balsam pear were studied. The results showed that the number of B. tau trapped in cushaw and cucumber at 80cm height field was more than two hosts. However, at 150cm the number of B. tau trapped was significantly reduced, and which showed that the movement activity oiB. tau was weak, and the results also revealed that its damage and activity mostly centralized below 80cm region. The results also showed that in field B. tau had obvious host selectivity and more liable to cushaw. Data supported this viewpoint were that the number of B. tau trapped in cushaw field was max and the rate of moth fruit also tiptop. Then towel gourd and cucumber, and the mean damage rate were 28.21% and 21.88%, respectively. However, the damage rate of balsam pear was min and the fruit damage rate was only 11.90%. Otherwise, the number of B. tau and fuit moth rate also nearly related with host field little climate and the difference of host vigorous fruit period.1.2 The extensive dynamic of 2?. tau in orange orchardThe extensive dynamic of B. tau under different distance and different height was carried out in orange orchard. The fit extensive height was 100cm in orange orchard, namely the number of B. tau trapped at 100cm height was more than 150cm and this tendency was same to the condition on melon fields. At different extensive distance of B. tau, the number of B. tau trapped at 10m was max, the follows are 5m and 20m, and the number at 15m was min and the total number was only 4. Theresults showed that the extensive distance of B. tau adult was in relation to both its flight activity and the wind direction. The number of B. tau trapped after released B. tau 2d was max, and the callback rate was 9.33%. As time went on, the number of callback was gradually decreased. The total number of adult B. tau by 4 times trapped was 43, and the total callback rate was 14.33%.2 Studies on relation of temperature and development, survival and propagation of B. tau2.1 Effects on development and propagation of B.tau under different temperaturesEffects on the development and propagation of B.tau under different temperatures (19℃., 22℃, 25℃, 28℃, 31℃, 34℃) were studied and the life tables under different temperatures were built up. The effect on the population increasing of temperature was analyst in this paper. The low-development threshold temperature of each stage and the effective thermal constants were figured out by the model of development period and temperature. The results showed that different temperatures had important influence on the development period, survival rate, adult longevity and oviposition number of B. tau female adult When temperature beyond 34℃, B. tau could not fulfill eclosion. The fit temperature ranges of B. tau population development were 25~31℃ and the fittest temperature was 28℃.At 28℃ and 31℃, the development period was significantly shorter than other temperatures, but there were no significant difference of egg hatch rates at different temperatures. There were no significant difference of larva periods between 28℃ and 25℃, 31℃, 34℃, but the survival rate at 28℃ was tiptop, and was significantly different with other temperatures. At 31℃, the pupa development period (6.31d) was significantly shorter than other temperatures. And at 28 ℃ and 34 ℃ the pupa period were 7.32 and 7.06d, respectively, and was significant different with other temperatures. At 28℃ the survival rate of pupa was max, 78.67%, which was significantly beyond other temperatures; at 34℃, the pupa of B. tau hardly came into eclosion to adult, and the pupa rate was only 3.9367%.The low-development threshold temperatures of each stage of B. tau was between 3.25℃ and 13.24℃, among all of which the threshold temperature of 2nd instar larvae was max and was 13.24℃. The threshold temperature of pupa was min and the effective thermal temperature was max, which were 3.2518℃ and 200.1420 d℃. And the effective thermal temperatures of egg was min and only 21.4563 d℃.The mean oviposition number at 28℃ was max, and was 105.9 eggs, and significantly beyond the mean oviposition number under other temperatures. At 31℃ and 28℃, the preoviposition period of female adult was shorter than other temperatures, 26.00d and 26.33d, respectively. At 19℃ and 22℃, the preoviposition period of female adult was significantly more than other temperatures. The results showed that at 28℃ the female adult oviposition number was max, the preoviposition period was less and the longevity of female adult was relatively lasting. So we concluded that 28℃ was the fittest temperature of female adult propagation, when temperature elevated or decined, its propagation both were restricted.At each temperature, the B. tau experiment population tendency index was between 0.6876 and 17.2855, among these the population tendency index at 28℃ was max and was 17.2855. At 19℃, the trend index of population was less than 1, and was only 0.6876. In comparison of B. tau life parameters, its population increase fittest temperature range was 25℃-31℃, in this temperature range, the intrinsic increase rate was 0.0408-0.0572. At 28℃, the inner increase rate of B. tau population (0.0572) was upper, the net increase rate (44.7576), finite rate of increase (66.4989) and population double time (12.0968) were biggish, namely 28℃ was fit to the development and propagation of B. tau; when temperature below 22℃, the net propagation rate and intrinsic increase rate were both inferior and temperature beyond 34℃; the pupa could not come into eclosion into adult and was not fit to the development and propagation.2.2 Effects on the propagation and survival of female adult under 5 temperatures and different adult feedingThe effect on preoviposition period, oviposition period, longevity and oviposition number of B. tau under 19℃, 22℃, 25℃, 28℃, 31℃ and under cushaw, cushaw+honey and honey as supplementary nutrition were carried out. At same temperature, cushaw+honey as supplementary nutrition preoviposition period, oviposition period, longevity of B. tau were all upper than preoviposition period, oviposition period, longevity of B. tau cushaw as adult feeding, however honey only as adult feeding, B. tau could not fulfill sex mature and oviposit. The longevity of female adult under each temperature cushaw+honey as supplementary nutrition was all max, otherwise honey only as supplementary nutrition the longevity was min. Cushaw+honey as supplementary nutrition at 28℃, the mean oviposition number of B. tau was max, 105.9 eggs which was significantly different with mean oviposition number of other temperature. Simultaneously, cushaw+honey as adult feeding, at each temperature the mean oviposition number were all more than the respective temperatures cushaw only as adult feeding.The survival curve line decreased slowest as cushaw+honey as adult feeding, honey only as... |
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