鍬(qiao)甲(qiāo jiǎ),亦稱鍬(qiao)形蟲,屬(shu)昆(kun)蟲綱Insecta,鞘(qiao)翅(chi)目Coleoptera,鍬(qiao)甲科Lucanidae,種(zhong)(zhong)內多(duo)樣性(xing)突出(chu),性(xing)二態(tai)現象(xiang)典型,很多(duo)種(zhong)(zhong)類雄(xiong)蟲具多(duo)型性(xing),因而是研究昆(kun)蟲進化(hua)和系統發育的很好的類群。全球已經(jing)記(ji)載有(you)近100 多(duo)屬(shu)1000 余(yu)種(zhong)(zhong)( Fujita, 2010) ,我國已經(jing)記(ji)載有(you)24 屬(shu)200 余(yu)種(zhong)(zhong)( Hua, 2002) 。由(you)于(yu)部分種(zhong)(zhong)類體(ti)型大、外形奇特而為(wei)(wei)大眾(zhong)喜(xi)愛(ai)和收(shou)藏,并作為(wei)(wei)寵物飼養、繁殖(zhi),已經(jing)成(cheng)為(wei)(wei)重要的標本商品(pin),具有(you)較好的經(jing)濟(ji)文化(hua)價值(zhi)。
鍬甲(jia)科昆(kun)蟲(chong)(chong),又名鍬形(xing)蟲(chong)(chong),長橢圓形(xing),多(duo)黑色或褐色大甲(jia)蟲(chong)(chong),有(you)金屬光澤,皮(pi)膚(fu)堅實,雄蟲(chong)(chong)上顎大而突出如鹿角(jiao)狀(zhuang),頭大而強,觸(chu)角(jiao)膝狀(zhuang)(如圖),11節,末(mo)端3節呈扇狀(zhuang),復眼大,上唇(chun)不顯,下顎與唇(chun)舌隱于下唇(chun)下顎,前基窩閉(bi)口,中(zhong)足基節幅廣,中(zhong)胸(xiong)板(ban)短(duan),后胸(xiong)板(ban)較大,鞘翅覆蓋(gai)全腹,跗節5節,第(di)5節最(zui)長。
幼蟲(chong)肥大,乳白(bai)色(se),充(chong)分成長后呈黃色(se),與金龜子幼蟲(chong)類(lei)似,但各節缺(que)3個膨起(qi)狀褶襞。一般生于朽(xiu)木中,腐植(zhi)土(tu)間,幼蟲(chong)移(yi)動范圍(wei)較(jiao)小,故發育程度(du)與其周圍(wei)環(huan)境食物豐富度(du)密(mi)切關系,多見于森林地帶。
鍬甲頭部常用分類特(te)征(zheng)實際就是成蟲的口器、觸角及復眼等(deng)器官在(zai)不(bu)同(tong)(tong)(tong)(tong)屬、種間的形態區別(bie),其在(zai)同(tong)(tong)(tong)(tong)種不(bu)同(tong)(tong)(tong)(tong)性(xing)別(bie)或(huo)同(tong)(tong)(tong)(tong)種雄(xiong)性(xing)不(bu)同(tong)(tong)(tong)(tong)個(ge)體中(zhong)也呈穩定(ding)的差異,從(cong)而呈現(xian)雌雄(xiong)二型(sexual dimorphism)和雄(xiong)性(xing)二型現(xian)象(male dimorphism)。
上顎(e)在這些(xie)特征(zheng)中最直觀,雄性(xing)上顎(e)通常長(chang)而強壯,多占(zhan)到體長(chang)的1/4~1/2,并(bing)附繁(fan)復的發達大(da)齒和密(mi)集小齒,雌性(xing)上顎(e)短小,不超過頭(tou)長(chang),僅(jin)具少(shao)數幾(ji)個小齒。
同種(zhong)鍬甲不(bu)(bu)(bu)同雄性(xing)(xing)的上顎(e)(e)(e)及其它頭(tou)部特征也呈(cheng)一定變化,具發(fa)達(da)上顎(e)(e)(e)的雄性(xing)(xing),其頭(tou)頂的各(ge)種(zhong)刺(ci)突、隆起或凹陷愈明(ming)顯,并隨上顎(e)(e)(e)漸變至不(bu)(bu)(bu)發(fa)達(da)而(er)趨不(bu)(bu)(bu)明(ming)顯,呈(cheng)現出雄性(xing)(xing)二型現象。進化生(sheng)物學中常(chang)提到“大型雄性(xing)(xing)(maior male)和小型雄性(xing)(xing)(minor male)”。前者體型較(jiao)(jiao)大,上顎(e)(e)(e)發(fa)達(da),通過與其它雄性(xing)(xing)廝(si)殺以(yi)保護領地(di)及獲得雌性(xing)(xing)的交(jiao)(jiao)配(pei)權;后者體型較(jiao)(jiao)小,上顎(e)(e)(e)不(bu)(bu)(bu)發(fa)達(da),它們(men)常(chang)避開(kai)直接(jie)打斗,采取偷(tou)襲策略以(yi)接(jie)近雌性(xing)(xing)與之交(jiao)(jiao)配(pei)。
具(ju)奇特的(de)(de)上(shang)顎(e)是(shi)鍬甲科的(de)(de)典型及重要(yao)特征之一。幼蟲(chong)期(qi)的(de)(de)上(shang)顎(e)用于啃咬(yao)各種(zhong)朽(xiu)木或(huo)腐殖(zhi)質土壤;在成(cheng)蟲(chong)期(qi), 雄(xiong)性(xing)的(de)(de)上(shang)顎(e)多異常發(fa)達, 被認(ren)為(wei)(wei)主要(yao)用于求偶爭斗(dou)中(zhong)的(de)(de)武器或(huo)在交配時幫(bang)助(zhu)抓持雌(ci)性(xing);雌(ci)性(xing)的(de)(de)上(shang)顎(e)多短闊, 被認(ren)為(wei)(wei)用于刺(ci)破樹(shu)皮以幫(bang)助(zhu)吸食汁液(ye)或(huo)協(xie)助(zhu)產卵。
完(wan)全變態,一(yi)生經歷卵、幼(you)蟲、蛹、成(cheng)蟲等4個(ge)蟲態,只能(neng)進行兩(liang)性生殖(zhi)。
成(cheng)蟲食液、訪花(hua)食蜜,部(bu)(bu)分具有肉(rou)食性,幼蟲腐食,棲食于樹樁及其根(gen)部(bu)(bu)等,能幫(bang)助(zhu)分解朽木和(he)腐植質,占(zhan)具著(zhu)獨(du)特的(de)生(sheng)態(tai)位,且具有開發生(sheng)物防治的(de)前景(jing)。成(cheng)蟲多夜出活動(dong),大部(bu)(bu)分種(zhong)類(lei)具有趨(qu)光性,也有白天(tian)活動(dong)的(de)種(zhong)類(lei)。
鍬形蟲(chong)的天敵有(you):喜(xi)鵲、獾、狐、刺猬(wei)和啄(zhuo)木鳥等(deng)。