| The western flower thrips, Frankliniella occidentalis(Pergande), is one of the most dageous worldwide pests, with small size, thigmotactic behaviour, omnivory, and having bisexual reproduction and parthenogenesis two reproductive modles with a high reproductive ability. Besides directly feeding plants by piercing-sucking mouthparts, it also spread impatiens necrotic spots virus, tomato spotted virus and other viruses. The effects of delayed mating, sublethal dosages of spinetoram and azadirachtin, temperature and pollen on adult longevity, fecundity, development were studied, while the similarities and differences of fecundity between different reproductive modles of F. occidentalis were assessed too. The results would provide basis data for forecasting the population dynamics and integrated management of F. occidentalis. The main results were as follows: 1. Effect of delayed mating on adult longevity and reproduction of F. occidentalisThe effect of delayed mating on adult male and female longevity, fecundity and offspring sex ratio of F. occidentalis were studied. The results showed that the longevity of both female and male adult was not affected by delayed at 0 h, 24 h, 48 h and 96 h after emergence. The fecundity was relative to mating time and more eggs were laid at 24 h and 48 h than that at 0 h and 96 h. Offspring sex ratio showed the tendency of female rate increasing firstly and then decreasing, with the highest value of 2.54: 1 female: male at 24 h after emergence. The pre-oviposition period increased gradually along with the time of delayed mating. 2. Sublethal effects of two biopesticides on the development and fecundity of F. occidentalisSpinetoram and azadirachtin sublethal dosages(LC25) against the 2nd instar larva of F. occidentalis was assessed with leaf immersion treatment, and their influences on development and fertility of F. occidentalis were studied. The results showed that two biopesticides had some degree effects. Under bisexual reproduction, pre-oviposition duration, female adult longevity and fecundity weren't affected by treatment of spinetoram, but male adult longevity was shorter 4.14 days than the control. Azadirachtin prolonged pre-oviposition duration, which extended 1.27 days and the fecundity was reduced, with loss 21.86%. Under parthenogenesis, both spinetoram and azadirachtin delayed the pre-ovipositon duration, with 2.60 days and 2.95 days respectively. Only azadirachtin decreased the female adult longevity of 19.30% and reduced its fecundity, with 24.65 eggs. Two biopesticides caused different effects on the development of next generation. No matter under which reproductive pattern, the development of immature stage treated by spinetoram was longer than that of azadirachtin. Intrinsic rates of increase(rm) and finite increase rate(?) of population treated by spinetoram were higher than control, was 0.1402, 1.1505 respectively, while they were lower treated by azadirachtin, was 0.1131, 1.1197 respectively. The results indicated that the effect of spinetoram and azadirachtin on the development and fecundity were relative to reproductive patterns. As a whole, spinetoram had positive effect, while azadirachtinon had significant inhibition effect. 3. Effect of temperature on adult longevity and reproduction of F. occidentalisUnder 19~31? and in bisexual reproduction, the male longevity shorten gradually along with the temperature increase,which were 14.70 days, 9.61 days and 8.11 days respectively at 19?, 25? and 31?. Offspring sex ratio increase gradually was 0.94: 1, 1.57: 1 and 2.25: 1(female: male). The highest fecundity of 93.22 eggs/ female was found at the 25?. Under parthenogenesis, the highest fecundity of 76.10 eggs/ female was found at the 31?. No matter under which reproductive pattern, the pre-oviposition and female adult longevity when the shortest at the 25?. They were 1.47 days and 15.68 days respectively under bisexual reproduction, while they were 1.95 days and 14.73 days respectively under parthenogenesis. The development of immature stage of offspring shorten gradually along with the temperature increase. Intrinsic increase rate(rm) and finite increase rate(?) of population increased gradually along with the temperature increase, the intrinsic increase rate(rm) was 0.0906, 0.1800 and 0.1901 respectively, the finite increase rate(?) was 1.0948, 1.1972 and 1.2094 respectively. The mean generation time(T) and population doubling(t) decreased with the temperature increased. The results indicated that temperature had significant impact of western flower thrips on fecundity and development. 4. Effect of males from different reproductive moldels on adult longevity and reproduction of F. occidentalisThe effect of males from different reproductive offspring moldels mating with female on audlt longevity and fecundity of F. occidentalis were studied. The results showed that the fecundity of F1(female) mating with F1(male) from bisexual reproduction was 72.4 eggs, which was haigher than that of bisexual reproduction F1(female) mating with the parthenogenesis F1(male). Two treatments had not significant influence on development of offspring. The offspring sex ratio of bisexual reproduction F1(female) mating with the parthenogenesis F1(male) was haigher than bisexual reproduction F1(female) mating with bisexual reproduction F1(male), was 1.41:1(female : male). rm was similar between male from different reproductive models. The results indicated that different reproductive offspring mating hadn't significant effects on population growth of F. occidentalis. 5. Effect of different preference pollen on adult longevity and reproduction of F. occidentalisThe differents of adult longevity and fecundity of western flower thrips between adding rape pollen and pine pollen on bena leaf were studied. The results showed that there was no significant difference of pre-oviposition and adult male longevity between adding pine pollen and rape pollen on bean leaf under bisexual reproduction. When adding pine pollen, the adult female longevity of thrips was 15.68 days, which was shorter than control, the fecundity of thrips wab 93.22 eggs/female,which was significant increased than control.The offspring sex ratio of thrips feeding two kinds of pollen were higher than control, with 1.57:1 and 2.53:1(female:male) respectively. Under parthenogenesis, the period time of pre-oviposition was prolonged than control with 2.70 days, while the adult longevity and fecundity were not affected by adding rape pollen. No matter under which reproductive pattern, the development of immature stage was significant prolonged than control, which indicated that adding rape pollen delayed nympha stage of F. occidentalis. Net reproductive rate(R0), intrinsic increase rate(rm), finite increase rate(?) of thrips feeding two kinds pollen higher than control, which were 29.0965, 0.1511 and 1.1631 respectively when feeding rape pollen, while they were 39.6679, 0.1800 and 1.1972 respectively when feeding pine pollen. The mean generation time(T) and population doubling time(t) of population were significantly shorter than control, they were 22.3065 days and 4.5873 days respectively when feeding rape pollen, while they were 20.4425 days and 3.8508 days respectively when feeding pine pollen. The results indicated that feeding rape pollen and pine pollencould stimulate the population rising, especially the pine pollen had more significant effect. |
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