象鼻(bi)(bi)蟲(chong)(Elaeidobius kamerunicus)是鞘翅目昆蟲(chong)中大(da)(da)的(de)(de)一(yi)科,也是昆蟲(chong)王國(guo)中種類(lei)多(duo)的(de)(de)一(yi)種,全世界已知的(de)(de)種類(lei)已超過6萬種,在我國(guo)種類(lei)可達(da)6000多(duo)種。象鼻(bi)(bi)蟲(chong)”祖籍(ji)西非大(da)(da)陸,體(ti)軀很小,頭上長著一(yi)根(gen)觸須,因形似象鼻(bi)(bi)故而(er)得名。大(da)(da)多(duo)數種類(lei)都有翅,體(ti)長大(da)(da)致(zhi)在0.1公分到(dao)10公分左右。其中“鼻(bi)(bi)子”占了(le)身體(ti)的(de)(de)一(yi)半。看到(dao)這(zhe)類(lei)昆蟲(chong)令人不由(you)得想起大(da)(da)象的(de)(de)長鼻(bi)(bi)子,因為它(ta)們的(de)(de)口(kou)吻(wen)(wen)很長,所(suo)以這(zhe)類(lei)昆蟲(chong)被人們稱為象鼻(bi)(bi)蟲(chong)。不過可別把長型(xing)的(de)(de)囗吻(wen)(wen)當成(cheng)象鼻(bi)(bi)蟲(chong)的(de)(de)鼻(bi)(bi)子,何況看生于末端的(de)(de)并不是鼻(bi)(bi)子,而(er)是它(ta)們用(yong)以嚼食(shi)食(shi)物的(de)(de)口(kou)器(qi)。當然(ran)除(chu)了(le)口(kou)吻(wen)(wen)長外,拐(guai)角著生于吻(wen)(wen)基部也是此蟲(chong)的(de)(de)特色之(zhi)一(yi)。
象鼻蟲(chong)(chong)(chong)(chong)體(ti)(ti)形很(hen)小,屬鞘(qiao)翅(chi)目(mu)curculionidae屬。雄蟲(chong)(chong)(chong)(chong)體(ti)(ti)形長(chang)×寬(kuan)為3.25mm×1.40mm,雌蟲(chong)(chong)(chong)(chong)為2.71mm×1.19mm。雄蟲(chong)(chong)(chong)(chong)鼻子平(ping)均長(chang)度為0.88mm,雌蟲(chong)(chong)(chong)(chong)為1.11mm。雌蟲(chong)(chong)(chong)(chong)的(de)個體(ti)(ti)比雄蟲(chong)(chong)(chong)(chong)小,平(ping)均長(chang)度在2.7~3.2mm之間。雄蟲(chong)(chong)(chong)(chong)的(de)眼(yan)睛裸露、鼻子較(jiao)短、體(ti)(ti)形大(da)些。在野外(wai)很(hen)容易辨認雄蟲(chong)(chong)(chong)(chong)和雌蟲(chong)(chong)(chong)(chong),可(ke)根據象鼻蟲(chong)(chong)(chong)(chong)身體(ti)(ti)的(de)大(da)小、鼻子的(de)長(chang)短對其(qi)性別進行鑒(jian)定,且雄蟲(chong)(chong)(chong)(chong)鞘(qiao)翅(chi)邊緣有絨毛。
因其(qi)喙(hui)像(xiang)大象的(de)(de)長鼻子而得(de)名(ming)。這種只吃棉(mian)(mian)花(hua)的(de)(de)昆蟲(chong),早是(shi)在中美(mei)洲發現(xian)的(de)(de),19世紀(ji)90年(nian)代(dai)初,它傳到了美(mei)國(guo)的(de)(de)布朗斯(si)維爾和德克薩斯(si)。象鼻蟲(chong)以一年(nian)70英里(113公里)的(de)(de)速度向(xiang)外移動(dong)。從1922年(nian)開始,落基山(shan)脈東部棉(mian)(mian)區都發現(xian)了象鼻蟲(chong),有很大的(de)(de)危害性。
象鼻(bi)蟲(chong)是比較(jiao)著名的(de)經濟(ji)植物(wu)害蟲(chong),不過并不是所有種類,也有些(xie)是不會(hui)對經濟(ji)植物(wu)造成危害。它吃(chi)棉花棵的(de)芽(ya)和棉桃,并在棉花上產卵。孵化出來的(de)幼(you)蟲(chong)是淺黃色(se)的(de)。幼(you)蟲(chong)頭部特別發達,能在植物(wu)之(zhi)莖內或谷(gu)物(wu)中蛀食。有些(xie)種類,甚(shen)至在根(gen)內穿刺。由于如此,每至風大的(de)時(shi)候(hou),作(zuo)物(wu)常(chang)從受害部折斷。
在(zai)國外,較著名的象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong)害有棉花(hua)的棉花(hua)象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong)針葉樹的白松象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong)、谷(gu)物的谷(gu)象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong)。在(zai)國內,除谷(gu)象(xiang)(xiang)(xiang)(xiang)、米象(xiang)(xiang)(xiang)(xiang)之外,較重要的象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong)類(lei)害蟲(chong)(chong)(chong)(chong),有為(wei)害香蕉(jiao)的香蕉(jiao)假莖象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong)、球象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong),為(wei)害甘蔗的蟻象(xiang)(xiang)(xiang)(xiang)及為(wei)害竹筍的臺(tai)灣(wan)(wan)大象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)等(deng)。 資深(shen)的蕉(jiao)農,對這(zhe)種(zhong)害蟲(chong)(chong)(chong)(chong),可能(neng)記憶(yi)猶新(xin);此蟲(chong)(chong)(chong)(chong)曾在(zai)臺(tai)灣(wan)(wan)中部地區的蕉(jiao)園內猖獗過,曾經(jing)臺(tai)灣(wan)(wan)當(dang)局在(zai)臺(tai)中收購的象(xiang)(xiang)(xiang)(xiang)鼻(bi)(bi)(bi)蟲(chong)(chong)(chong)(chong)數量(liang)兩千七百多公斤來看(kan),不難(nan)窺(kui)知其為(wei)害之烈。
象鼻(bi)蟲(chong)(chong)只以(yi)(yi)雄花(hua)(hua)粉為(wei)(wei)食,而幼蟲(chong)(chong)則以(yi)(yi)腐爛(lan)的(de)花(hua)(hua)為(wei)(wei)食并(bing)逐(zhu)漸變(bian)為(wei)(wei)成蟲(chong)(chong)。在(zai)油棕雄花(hua)(hua)期間,象鼻(bi)蟲(chong)(chong)在(zai)快(kuai)要枯萎的(de)小(xiao)花(hua)(hua)細絲管內產卵(luan),其(qi)幼蟲(chong)(chong)以(yi)(yi)腐爛(lan)的(de)花(hua)(hua)為(wei)(wei)食,從卵(luan)到成蟲(chong)(chong)大(da)約需要7~14天(tian),正好是在(zai)雄花(hua)(hua)花(hua)(hua)期內。象鼻(bi)蟲(chong)(chong)的(de)平均壽命為(wei)(wei)15~17天(tian),一個雌蟲(chong)(chong)平均繁(fan)殖(zhi)12個后代。
象鼻(bi)蟲(chong)的(de)(de)雌蟲(chong)在產(chan)(chan)卵(luan)前,往往會(hui)以吻端之囗器在植物之組(zu)織上(shang)鉆一管狀洞(dong)穴或橫裂(lie),然后再把卵(luan)產(chan)(chan)于組(zu)織內,有(you)(you)部份(fen)種(zhong)類能以孤雌生(sheng)殖方(fang)式絮衍后代(dai)。它的(de)(de)整個(ge)壽命只有(you)(you)三個(ge)星(xing)期,但(dan)成蟲(chong)只需活(huo)幾個(ge)星(xing)期就可以不斷地產(chan)(chan)下4代(dai)甚至(zhi)更多的(de)(de)后代(dai)。但(dan)在秋天只有(you)(you)百分之九十五的(de)(de)成活(huo)率(lv)。
對(dui)這類(lei)(lei)甲蟲(chong)可感興趣?它(ta)們不會咬(yao)人(ren),成蟲(chong)擁有假(jia)死的習性(xing),并且(qie)一(yi)些大(da)型的種(zhong)類(lei)(lei)還挺好玩的呢(ni)。
松(song)象(xiang)蟲(chong)(chong)在(zai)(zai)小興安嶺林區,兩(liang)年(nian)(nian)一代。以成(cheng)(cheng)蟲(chong)(chong)及幼(you)蟲(chong)(chong)兩(liang)蟲(chong)(chong)態越(yue)冬(dong)。5月(yue)中(zhong)(zhong)下旬,越(yue)冬(dong)成(cheng)(cheng)蟲(chong)(chong)開(kai)始活(huo)功(gong),集中(zhong)(zhong)于落(luo)葉(xie)(xie)松(song)更新(xin)地上取食(shi)(shi)并交尾,危害2年(nian)(nian)生以上的(de)(de)(de)幼(you)樹(shu)。6月(yue)中(zhong)(zhong)旬以后,成(cheng)(cheng)蟲(chong)(chong)自更新(xin)地向采伐(fa)跡地擴散,到伐(fa)根(gen)下去產卵。6月(yue)下旬以后新(xin)孵化(hua)的(de)(de)(de)幼(you)蟲(chong)(chong)陸續出(chu)現,在(zai)(zai)伐(fa)根(gen)的(de)(de)(de)皮(pi)層或皮(pi)層與邊(bian)材(cai)之間作隧道(dao)活(huo)功(gong)取食(shi)(shi)。到9月(yue)末,大部(bu)分(fen)幼(you)蟲(chong)(chong)已(yi)經(jing)(jing)老(lao)熟,在(zai)(zai)皮(pi)層,皮(pi)層與邊(bian)材(cai)間或全部(bu)在(zai)(zai)邊(bian)材(cai)以內作橢圓形蛹(yong)室休(xiu)眠(mian)(mian)。少數孵化(hua)較晚(wan)的(de)(de)(de)幼(you)蟲(chong)(chong),越(yue)冬(dong)時(shi)尚未(wei)老(lao)熟,翌春需(xu)再取食(shi)(shi)一段(duan)時(shi)間,才作蛹(yong)室休(xiu)眠(mian)(mian)。上年(nian)(nian)秋(qiu)末已(yi)經(jing)(jing)老(lao)熟的(de)(de)(de)休(xiu)眠(mian)(mian)幼(you)蟲(chong)(chong),經(jing)(jing)越(yue)冬(dong)階段(duan)后,于7、8兩(liang)月(yue)化(hua)蛹(yong),7月(yue)末以后開(kai)始羽(yu)化(hua)為(wei)成(cheng)(cheng)蟲(chong)(chong)。大部(bu)分(fen)新(xin)成(cheng)(cheng)蟲(chong)(chong)潛伏蛹(yong)室中(zhong)(zhong)約半月(yue)后,即(ji)自伐(fa)根(gen)爬出(chu)土(tu)面(mian)來,找尋幼(you)材(cai)取食(shi)(shi)為(wei)害。當年(nian)(nian)不(bu)交尾產卵。9月(yue)底后,在(zai)(zai)落(luo)葉(xie)(xie)松(song)幼(you)樹(shu)根(gen)際的(de)(de)(de)枯枝落(luo)葉(xie)(xie)叢中(zhong)(zhong)越(yue)冬(dong);少數羽(yu)化(hua)較晚(wan)的(de)(de)(de)成(cheng)(cheng)蟲(chong)(chong),并不(bu)出(chu)土(tu),在(zai)(zai)蛹(yong)室內越(yue)冬(dong)。自卵孵化(hua)而至羽(yu)化(hua)成(cheng)(cheng)蟲(chong)(chong),成(cheng)(cheng)蟲(chong)(chong)再產卵,歷時(shi)二(er)周年(nian)(nian)。