行政院農業委員會台南區農業改良場  研究彙報第12號

甘藷鳥羽蛾Ochyrotica concursa W生態及防治研究

顏福成

摘  要

茲將在台南調查甘藷鳥羽蛾之發生生態等,結果摘要如下:

1.本蟲在台南年發生有12世代

 一世代所要日數:19∼50日  平均27.8日

 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

2.成蟲在日間靜止於莖葉上或土面上。至傍晚或早晨交尾,將卵粒產於未展開之心葉或葉片上。

3.雌蛾羽化後產卵情形如下:

 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

 一雌一生產卵數:0∼99粒  平均22.9粒

羽化後2~6日之產卵數較多,1.7.8日次之。

4.雌蛾期間,若逢空氣太乾燥(相對濕度73%以下)其產卵數隨之減少。

5.成蟲之雌蟲率42.9∼69.6%,平均53.2%,通常雌蟲較雄蟲略多。

6.成蟲壽命,雌蛾較雄蛾略長,雌蛾2∼20日平均8.1日,雄蛾2∼19日平均7.1日。

7.卵之孵化率49∼90.2%,平均73.5%。

8.甫孵化幼蟲潛入未展開之心葉內食害,使心葉縮緬或枯死,或葉片上留有千瘡百孔之食痕。

9.老熟幼蟲大部份在葉面主脈基部化蛹。幼蟲化蛹率57.5∼87.5%,平均71.0%。

10.成熟蛹,日夜間均可羽化,其羽化率87.5∼100%平均92.8%。

11.本蟲在台南周年發生以9∼3月間較多,其中12∼3月間最多,4∼8月間較少。以甘藷插植期而言5∼11月插植者發生較多,其中8∼10月最多,12∼4月較少。

12.本蟲之發生,南部較北部為多,其中台南縣最多。全省調查31鄉鎮之被害葉率平均18.4%。海拔越高本蟲發生越少,至1,500公尺處(十字路)尚有本蟲之發生。

13.本蟲為害對塊根產量損失,於插植後2個月內被害葉率若在15%以下及至4個月內被害葉率若在5%以下之程度,對產量影響輕微,無防治價值。一般無防治區之被害葉率為18.2%,塊根減收率為8.9%。

14.本蟲發生概以葉茸毛多、葉狹小、莖葉濃色品種為較少。


Ecological and Control measures studies on the sweet potato plume moth (Ochyrotica Concursa W.)

Fu-Cheny Yen

Summary

        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.



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