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Studies on Control Techniques and Mechanisms by Entomophilic Nematode and Sex Pheromone for the Beet Armyworm, Spodopter Exigua

Author: QianKun
Tutor: ZhuShuDe;LuoLiZhi
School: Yangzhou University
Course: Agricultural Entomology and Pest Control
Keywords: Beet armyworm Ovomermis Parasitic effects Mating Fertility Sex pheromone Population monitoring Prevention and control technology
CLC: S435.66
Type: Master's thesis
Year: 2003
Downloads: 105
Quote: 1
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Abstract


Beet armyworm Spodoptera exigua Hübner is an important pest of development over the past dozen years, has great economic losses caused by the growth of China's agriculture and animal husbandry, and will continue to be a threat to the agricultural and livestock production. Parasitic efficiency the Ovomermis of the beet armyworm larvae and related factors for the occurrence of the beet armyworm infestation law as well as the main problems in the fight against beet armyworm adult mating behavior and ability, mating on oviposition and hatchability effect, the male moth trapping technology and related factors, the application of the sex pheromone technology, and the role in the prevention and treatment of beet armyworm Research was carried out, more meaningful results major: study clearly the Ovomermis Ovomermis sinensis beet armyworm larvae infected clear parasitism rate environment physiological factors. Study results showed that the infection rate of of indoor applications Ovomermis beet armyworm larvae, infected larvae behavior physiological characteristics, as well as parasitic effects related factors, beet armyworm larvae is the sensitive Ovomermis host, parasitic rate up to 80%. Nematode larvae after infection in eight days that nematodes released from the larvae of the first nine days of the peak. Infected larval development period is extended, and die because they can not go to the next developmental stage. Compared with the non-parasitic larvae of the same age, the larvae are parasitic and food consumption and growth volume significantly decreased, but hemolymph protein content increased significantly. Temperature, beneficial than harmful and disposal of time is the main environmental factors influencing nematode parasitic. At 20-32 ° C the temperature of 28 ° C under the condition of parasitic effects, beneficial to harmful ratio under the conditions of from 10:1 to 40:1, preferably 20:1 parasitic effects. The nematode larvae disposal time for 30 minutes to obtain a parasitic rate of 49%, while the parasitic effect is also increased due to the disposal of the extension of the time. In addition, with the results of the the 3-5 instar beet armyworm larvae infected no significant differences, namely Ovomermis parasitic instars of the beet armyworm larvae. These results suggest that comprehensive prevention and control of the beet armyworm, Ovomermis has good application prospects. Clear beet armyworm adult mating behavior and ability, clear effect than mating ability of male and female adults. 27 ± 1 ℃, photoperiod L14: D10 under the experimental conditions of the mating behavior of the beet armyworm, ability, and mating spawning and hatching were. The main results obtained for: adult feathering the night can be mated, mating rate eclosion during the first three nights of high (> 82%), but four days decreased significantly. Adult day mating time between 05:30 a 23:30 mating peaks in the 01:30 to 02:30 and 03: oo to 04:00 between the frequency of the occurrence of the first peak higher . Adult mating the f Division duration ranging from 22 191 minutes, but 30 60 car for more (40.8%, n = 97), 60 to 90 minutes, followed by (19.4%), more than 180 minutes less (10.20,0). In addition, the mating duration f, j and moth age are closely related. The longer the older the moth mating duration, and the difference is significant. Mating ability of male moths life ranging from 11, but by the impact of the sex ratio significantly: in the sex ratio of l: l conditions, the average male moths mating frequency is only 3.0 times in 2 as early as: 1% earlier to 5: 1 accounted for, increased to 5.1 or 6.0 times. The proportion of female moth mating the proportion and number of times by the sex ratio is also great: without mating female moth from l: 1 to 8.3% to 5: 1 accounted for as early as 32%, only mate once the proportion increased from 16.7% to 38.7%, mating) five times the proportion decreased from 25% to 0%. Therefore, in the application of pheromone control of beet armyworm process, only the proportion of male moths and female moths dropped to an accounting: 4 as early as before 'to get better control effect. The study defined the effects of the beet armyworm mating adult fecundity and egg hatchability. Fecundity and Hatchability of the female moth mating period in female moth mating period, mating frequency and male moth mating order three acting factor most significantly: The later time female moth mating, spawning The amount and hatchability lower, and vice versa, blade 'contingent. The female moth mating frequency significant impact on the fecundity, spawning amount will increase with the increase in the number of mating. The female moth mating frequency, although no significant effect on hatchability, but the fecundity of the female moth mating frequency, while the hatching rate did not decline. Thus, the increase in the number of copulations virtually increase the rate of fertilization of the egg, and thus on the the increased hatchability important effect. The kinds of results to determine the the beet armyworm mating type belongs to the true multiple mating type. The obtained results also show that the number of female moth mating with life was positively correlated with the long life of the female moth mating frequency, high fecundity. Male moths fine bead size decreases with the increase in the number of male moths mating, but the size of the fine beads no significant effect on the fecundity and egg hatchability, male moths each mating Fecundity and Hatchability is the same. This way, in sex pheromone practice, in addition to effectively reduce the number of male moths, as long as we can postpone the female moth mating period or reduce the number of female moth mating can get better control effect. Preliminary study to clear the sex pheromone of the beet armyworm populations in the field monitoring, prediction and prevention, and part of the existing use of the technology to put forward suggestions for improvement. The results showed that the synthetic pheromone lures and lure two catch monitoring field populations large number of sex pheromone trapping of male moths significantly predicted adult peak forecast first instar larvae peak period, the peak of coincides with the field actually occurred; the male moths nocturnal time from 0:00 to 05:00 midnight, 04:00 before male moth trap catches in total 66.9% of the induced set. This is consistent with the result of observation of the indoor. On the basis of clear basin traps trapping male moths is better than the triangular traps, screening and the the basin traps liquid medicine with force, and installation of the use of technology. Application male moth trapping control methods to prevent and treat the field beet armyworm, set six lures per acre, the the field larvae density and crop victimization rate gradually decreased, up to 45 days after the control effect%%. These results suggest that the sex pheromone is an effective means for monitoring and control of the beet armyworm, should strengthen the popularization and application.

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CLC: > Agricultural Sciences > Plant Protection > Pest and Disease Control > Crop pests and diseases and their prevention > Economic crop pests and diseases > Sugar crop pests and diseases
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