黃帶黑翅蕈蠅生態觀察及防治試驗

Abstract

黑翅蕈蠅爲目前本省洋菇之重害蟲，而以黃帶黑翅蕈蠅發生極爲普遍，被害菇床嚴重者之產量減損幾達3/4。近年來就其生態觀察及防治試驗，摘要簡述於下： 一、黃帶黑翅蕈蠅(Bradysia tritici Coquillett)屬黑翅蕈蠅科(Sciaridae)，成蟲體長約2.6mm，黑褐色，胸側具淡黃色縱帶。具趨光，但在黑暗菇舍中照常能活動，飛翔時動作頗緩慢，棲息靜止時甚遲鈍，爬行動作稍敏捷，靜止或爬行時雙翅張開。通常在菇床邊緣堆肥及床底下棲息，亦有棲息在菇床支柱及菇床表面，且時常爬至洋菇上。雌蟲壽命爲1~5天，平均3.14天。 二、觀察1,091隻成蟲羽化時刻以8:30前爲最多，約佔65%，其後每1小時之羽化比率爲8:30~9:30 11.2%，9:30~10:30 11.9%，10:30~11:30 4.9%，11:30~12:30 3.3%，12:30~13:30 2.9%，13:30~14:30 1.0%，14:30~15:30 1.1%，15:30~16:30 0，16:30~17:30 0.2%。 三、成蟲羽化後不久就能交尾，交尾時刻以早晨較多，交尾時間自2.5~8.5分鐘，平均4分鐘。雌蟲交尾當日或經1~2天就能產卵，每l雌蟲於交尾後可分數次產卵，產卵數因季節稍有不同，自55~195粒不等，平均132粒。卵呈橢圓形，乳白色，長0.2~0.8 mm，平均0.25 mm，如念珠狀排例，或數粒至數十粒堆在一起，孵化前近中央處可見有黑黙，即爲幼蟲之頭殼。在20.5℃時經4~7天孵化，平均5.2天。卵之孵化率爲95%左右。 四、幼蟲乳白色，光亮、半透明。頭殼黑色，頗大，大頭甚發達。體軀12節，在第2齡以後可見體內黃褐色或褐色內臟。幼蟲脫皮4次，每次脫皮後頭殼爲無色透明，約經半小時後變爲灰色，、稍後轉變爲黑褐色至黑色。幼蟲在食料不足時或蟲體擁擠時有自相殘殺行爲。幼蟲第l~4齡體長爲0.5~0.7，1.5~2.5，1.8~3.7，2.5~5.8mm，在20℃各齡所需發育時間爲2~(2.9)~8，2~(4.2)~7，2~(4.3)~6及5~(7.4)~10天，老熟幼蟲常能吐出少量絲絹，織成極簡陋蛹室。 五、化蛹前蟲將體內雜物排出，身體稍縮短而停止活動，然後脫皮化蛹。蛹爲被蛹(Obtect pupa)，乳白半透明，時常或於受擾動時腹部末端能迅速打轉。羽化前漸變淡黃，複眼亦由淡褐色變爲黑色，前翅、觸角及腳均漸次變爲黑色，體色加深後即羽化。雄蛹腹部末端具有一對彎曲握器(Clasper)可與雌蛹分别，雄蛹長1.8~(2.1)~2.5 mm，雌蛹長2.3~(0.5)~3.3 mm，蛹期2~(3.5)~5天。 六、黑翅蕈蠅生活受溫度影響頗爲明顯，其發育時間隨溫度升高而縮短，年約發生14世代，在平均20.5℃以洋菇飼育觀察一世代需28天。 七、成蟲在野外較低溫而略潮濕之樹蔭處活動，幼蟲以植物質朽木屑及腐爛落葉之腐植質爲食料，在菇舍中則以洋菇菌絲、小菇蕾、菇體、堆肥爲食料，菇床中菌絲及小菇蕾受害，田菇數量即銳減。且能爲害鮑魚菇(Pleurotus cystidiosus Miller)，高溫菇(Agaricus bitouquis)及木耳類(Auricularia spp.)等其他裁培菇類。 八、成蟲天敵有粘質沙雷氏菌(Serratia marcescens Bizio)，在4月份以後較高溫時寄生，及Entomophthora sp。在濕度較高之菇舍中寄生。幼蟲天敵除粘質沙雷氏菌在4~6月間寄生外，尚有寄生性之開顋蜂（Asobara sp., Aspilata sp., 及Synaldis sp., Alysia sp.），釉癭蜂(Trybliographa sp., Pscudiranchis sp. Pseudeucoila sp.)及黑小蜂(Spalangia nigra Latreilla)，並發現有捕食幼蟲之圍眼癭蠅(Colpodia sp.)及蟎類4種，即褐蟎、溝蟎、尖蟎及彎腳蟎，此類捕食蟎在4月以後高溫時對幼蟲之抑制能力甚強。其他尚有閻魔蟲、蚜蟲、隱翅蟲等能捕食幼蟲。 九、黑翅蕈蠅爲害菇類均爲幼蟲期，因其潛藏在裁培材料中，故防治較爲困難。以DDVP 50% EC 0.5 ml/M^3使用藥量燻殺成蟲，效果甚佳，方法簡便。另以藥膜法(Residue film)測定Diazinon 60% EC稀釋60倍預防成蟲，藥膜效果可達25天，Malathion 50% EC稀釋50倍可達36天，Sumithion 50% EC 50倍達50天，Sevin 50% WP，MIPC 50% WP，及Meobal 50% WP各50倍稀釋液均達50天，Dursban 40.8% EC 40倍及Baythion 50% EC 50倍均達73天以上，而以Dimethoate，Azodrin，Monocron，Gardona，Nankor，Fenthion，Dipterex及Padan之藥膜觸殺效果最差。 十、以8種藥劑稀釋液進行第4齡幼蟲毒殺試驗，結果發現Gardona，Dipterex及Monocron均無效果。Nankor效果極差。Malathion （0.025%有效成分），DDVP （0.025及0.05%有效成分）及Safrocide 4-40%之1,000倍稀釋液雖可達95%以上毒殺效果，但由於濃度過高恐有礙菌絲生育或菇體殘毒問題，故未便於菇床上使用。 1. Bradysia tritici Coq. is a serious pest of mushrooms in Taiwan. Under severe situation, 3/4 of the crop may be destroyed. 2. The adult is phototropic and the female has a life span of 1-5 days (av. 3.14 days). The emergence from the puparium occurs mostly in the morning, and some after that. Mating also takes place in the morning. Each female may lay 55-195 eggs, in several batches. 3. The eggs last 4-7 days (av. 5.2 days) and the hatching rate about 95%. 4. There are 4 larval instars. Under average temperature of 19.6°C, the average periods of the instars are 2.9, 4.2, 4.5 and 7.4 days, respectively. The mature larva secrets a small quantity of silk and spins a very crude pupal cell. 5. The pupal period lasts 2-5 days (av. 3.5 days) under 23.4°C. 6. The developmental rate of the immature stages depends on temperature. Generally 14 generations may be completed in each year, and each generation takes about 28 days under 20°C. 7. In the wild, adults are active in cool, humid and shaded places, and larvae feeds on decaying plant materials. In the cultivation areas of mushroom, the larval development can be completed in the compost manure used for the cultivation but more often on various kinds of cultivated mushroom including Agaricus brunnescens, A. bitorquis, Pleurotus cystidiosus, and Auricularia spp. 8. Natural enemies of the adult include the fungi Serratia marcescens and Entomophthora sp. Those of the larva (and/or pupa)include the bacteria S. marcescens, 4 species of alysiid wasps, 3 species of cynipid wasps, I species of pteromalid wasp, a predacious cecidomyiid midge, and4 species of predacious mites. In addition, 2 histerid, 2 hydrophilid and several staphylinid species of beetles may occasionally prey on both adult and larva. The most important natural enemies are fungi and mites. 9. For the control of the adult, the use of DDVP 50% EC at 0.5 ml/M^3 as a fumigant is effective and simple; the use of Sumithion 50% EC, Sevin 50% WP, MIPC 50% WP, Meobal 50% WP, Baythion 50% EC (each diluted to 1% solution) or Dursban 40.8% EC (diluted to 1.02% solution) as a residue film for contact poisoning is also effective and lasts 50 or more days. The malathion 50% EC and Diazinon 60% EC (each is diluted to 1% solution) are effective and lasts 36 or 25 days, respectively. The Dimethoate and some other chemicals are either less effective (or even ineffective) or do not last long. 10. For the control of the 4th instar larva, Malathion (0.025%.), DDVP (0.025 and 0.05%.) and Safrocide 4-40% (diluted to 0.4% solution) may kill more than 95% larva but are not recommented because of possible harm to mycelial growth and possible poison residue on mushrooms. Gardona, Dipteres, Monocron and Nankor showed little or no effects.