甘藷鳥羽蛾Ochyrotica concursa W生態及防治研究
卵 期 間： 2∼9 日 平均 4.3日
幼 蟲 期 間：10∼31日 平均17.0日
蛹 期 間： 3∼14日 平均 6.6日
羽化至產卵期間：1∼ 7日 平均 3.0日
產 卵 期 間：1∼12日 平均 4.1日
一雌一日產卵數：0∼49粒 平均 7.7粒
Ecological and Control measures studies on the sweet potato plume moth (Ochyrotica Concursa W.)
The ecological studies on sweet potato plume moth had been taken at Tainan DAIS, and now the results are summarized as follows:
1. The sweet potato plume moth has 12 generations in southern Taiwan each year. The days needed for the completion of one generation are ranged from 19 to 50 days and 27.8 days in average. The egg stage duration is ranged from 2 to 9 days and 4.3 days in average. The larval stage duration is ranged from 10 to 31 days and 17.0 days in average. The pupal stage duration is ranged from 3 to 14 days and 6.6 days in average.
2. The adults always stay quietly on the surface of leaves or earth during the day time and the mating always take place in the dusk or dawn. The female moth lays eggs mostly on the rolled and tender leaves and some on other leaves.
3. Some characteristics of egg-deposition by female moth after emergence is described as follows: The duration for preoviposition (from emergence to egg-deposition) is ranged from 1 to 7 days and 3.0 days in average. Egg-deposition is lasted from 1 to 12 days, 4.1 days in average. The number of eggs deposited per female moth per day is ranged from 0 to 49 and 7.7 in average. The total number of eggs deposited per female moth in whole life is ranged from 0 to 99, 22.9 in average.
4. Low humidity (lower than 73%) could cause the decrease in the number of eggs deposited by female moth.
5. The percentage of female moth occupied 42.9 to 69.6% and 53% in average. This indicates that the female’s number is more than male’s.
6. The longevity of male is lasted from 2 to 19 days, 7.1 days in average, and that of female is ranged from 2 to 20 days, 8.1 days in average.
7. The percentage of egg hatching is 49 to 90.2% and 73.5% in average.
8. The newly hatched larvae prefer to feed on the rolled young leaves, and left numberless feeding scar on the leaves.
9. The full-grown up larvae are used to pupating at the base of leaf blade. The percentage of pupation is ranged from 57.5 to 87.5%, 71% in average.
10. The emergence is taking place either in the day time or at night. The percentage of emergence is ranged from 87.5% to 100%, 92.8% in average.
11. The seasonal occurrence period of the moth are from September to March next year; the population peak is occurred December to the following March, and from May to August is the lowest in population. If the sweet potato is planted from May to November, then it would subjected to heavier plume moth infestation than that is planted in the period from December to the following April.
12. In the southern part of Taiwan, the population of this pest is bigger than that in the north of Taiwan and Tainan Hsien has the biggest population in the whole island. According to the results of investigation of 31 towns in Taiwan, the average percentage of leaf feeding damage is 18.4%. At the place of 1500 meters above sea level, the moth was still found there. But the higher the sea level, the fewer the moth occurs.
13. If the percentage of injurious leaves is lower than 15% 2 months after planting or lower than 5% 4 months after planting, then it could not constitutes the significant losses in the root yield. Hence, in these situations, it is not worth to control. At check plot, the percentage of the injurious leaves is 18.2%, and the yield of root will be decreased by 8.9%.
14. This pest shows no preference to occur in the sweet potato varieties which leaf characters are hairy, narrow leaf-blade and in deep color.
15. According to the investigation, this pest host plants are sweet potato and water convolvulus (Ipomoea aquatica).
16. Up to now, five natural enemies have been found. Among them there are 1 larval parasites: Apanteles S. P., 2 pupal parasite: Brachymeria S. P., Centeterus S. P. and 2 larval predators: Euborollia pallipes, Cuntheconidea furcollata.
17. There exists Ceraphron kamiyae and Tetrastichus S. P. in the sweet potato field.
18. For controlling this pest by using the diluted solution of 0.05% products such as Azodrin, Sumithion or phosvel obtained better results.