| Apolygus lucorum, Heteroptera:Miridae, outbreaks frequnetly in cotton crops recent years and it has become the primary pest in agricultural production. There are three main reasons which lead to this phenomenon:the widespread adoption of Bt cotton controlled Lepidoptera successfully; the reduction in insecticide use; the pattern of cultivation had changed in the farmland ecosystem these years;In order to understand the population dynamics and the adaptability of Apolygus lucorum more deeply, three aspects experiments about Apolygus lucorum were conducted in these paper, that were:the effect of temperature, photoperiod on the development, survival and fecundity, respectively; the activities of protease, amylase and trehalase and the content of trehalose in laboratory populations of Apolygus lucorum reared on different hosts. The results of these aspects experiments may provide a scientific basis for prediction and control to Apolygus lucorum. The main results were summarized as follows.1. Life tables of Apolygus lucorum laboratory population at five different temperatures(18℃,21℃,24℃,27℃,30℃)were constructed. These results showed that the development rate increased with the temperature rising, and the relationship between them could be simulated using the Logistic model. The developmental temperature thresholds required for egg, nymph, preoviposition and generation were 9.53℃,12.32℃, 10.40℃,11.07℃; the effective accumulated temperatures were 142.61,162.60,123.13, 425.17 degree day respectively; The survival rate was 27.27%higher the max value (24℃) than the min value(30℃); The average fecundity of female adults was 33.61 more the maximum(24℃) than minimum(30℃). The intrinsic rates of natural increase(rm) was the highest at 24℃, and the temperature zone (24-27℃) was the favorable temperature for Apolygus lucorum. This study provided foundation to ascertain the effective temperature on Apolygus lucorum population and enriched investigation and forecast in field with the effective parameters. 2. The effects of different photoperiods(L:D=8:16,10:14,12:12,14:10,16:08) on the characteristic of development and fecundity about Apolygus lucorum was studied using life table methods. Apolygus lucorum was reared in climate incubator with temperature (25±1)℃, relative humidity (70±5)℃and illumination intensity 4000 Lx. The survival rates of each stadium, preoviposition duration and fecundity of female adults were significantly different among the five photoperiods. The maximum hatching rate(L:D=10:14) was 25.06%higher than the minimum (L:D=16:8); the highest nymph survival rate(L:D=8:16) was 25.26%higher than the lowest(L:D=16:8); the maximum average fecundity (L:D=12:12)of female adults was 27.29 more than the minimum(L:D=8:16). In the photoperiod L:D=12:12, the intrinsic rates of natural increase(rm) was the largest(0.1093) while the double time(DT) was the shortest (6.3417) which indicated that the photoperiod L:D=12:12 was very beneficial to development and fecundity of Apolygus lucorum. This study provided foundation to the research of diapause and forecast in field.3. The protease activity, amylase activity, trehalase activity and the content of trehalose were examined in laboratory populations of Apolygus lucorum that reared on kidney bean, cowpea, mung bean, regular cotton Su 9 and hybrid cotton E10. The protease, amylase activity for mung bean were the highest while the Su 9 were lowest,2.09μg/(mg. min),15.35μg/(mg . min)between the max and the min, respectively(p<0.01). The trehalase activity for E10 came to the peak was at 3.74 mmol-1/(mg . min)(p<0.05), however, the trehalose content came to the valley was at 3.03μg/adult(p<0.01). The frequency differences were obviously among these five populations. The results indicated that Apolygus lucorum had strongly physiological adaptation. Our studies could provide the foundations for the study of host adaptability and integrated control methods of Apolygus lucorum. |
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