Cytogenetical Studies of Some Ladybird Beetles (Coleoptera: Coccinellidae) of Bangladesh

Abstract

Twenty species or lady beetles, Hodalia fitfvescens Hoang, Sterthorus tetranychi Kapur, Scymnus nuhilus Mulsanl, /Jrumoides lineatus,(Weise), .Jauravia pallidula Motchulsky., Pharoscymnus taoi Sasaji, /lids indica Timberlake, Psyllobora hi.wJc.:tonolala (Mulsanl), ( 'heilomenes sexmaculata (Fahricius). Cuccinella septempunc.:fala Linneaus, Coccine/la lransve,~wlis Fabricius, Harmonia octomac.:ulata (Fabricius), Mic.:raspis discolor Fabricius, Micraspis yasumatsui Sasaji, propylea quatuordecimpunctata Linneaus, Apomicraspis quayumi Ali & Rahman, Ajidenta misera Mulsant, l~iJilachna septima (Mulsant), Hpilachna pusillanima (Mulsant) and hpilac.:hna viginfioctopunc.:tata (Fabricius), belonging to 16 genera of the six sub families; Coccidulinae, Scymninae, Chilocorinae, Sticholotidinae, Coccinellinae and Epilachninae under the family Coccinellidae of Coleoptera of Bangladesh have been cytogenetically investigated. Detailed comparison of karyotype usmg principal components analyses revealed a considerable divergence among the 20 species. Sex determining mechanism 1s common with a large X chromosome and a minute y chromosome in a nonhomologous formation. The lowest number of chromosomes obtained 2n=i4 in present investigation from the spcmatogonial cell of Sc.ymnus nuhilus and Ajidenta mesera with the karyotype fomula 6AA+ Xy. The species Harmonia octomaculata and J{ 1msillanima showed 211= 16 with the Karyotype 7 AA+Xy. Diploid number of chromosome in the four species /3rumoides Linea/us, .Jauravia palbdula, p.,yllobora hisoc.:tonotata and hpilachna vigintioclopzmctata were 18 with the karyotype formula 8AA + Xy in each case. Other 12 species of present investigation have shown the modal number of chromosomes 2n=20 with the karyotype 9AA+Xy. X chromosomes were sub metacentre 111 the five (5) species Cocc.:inella septempunc.:tala, Harmonia oc.:tomc:ulata, Micra.,pis discolor, M. yaswnatsui and A.fidenta misera. Other 15 species showed metacentric type or X chromosomosome. Variations of centromcric position were found in autosomes of the 20 species. Of the autosomes most are metacentric type than submetaecntric and few are telocentric. The ratio of autosomes showed a great diversity. In each case last pair of autosome showed minimum value ranged from 5.2 I% in I.!.:. septima to 9.8% in Ajidenta misera, while I st pair of autosome showed highest value ranging between I 0.67% in PropyLea quaruordecimpunctata to 17.10% in A.fidenta misera. Sex chromosome ratio were highest in the total numbers of chromosomes in each species, which found .highest 18.82% in scymnus nubiLus and J 8.8% in /.:,JJilachna viginfioctopunctata and lowest 12.18% in P.\yllobora bisoctonofata. Chromatographical analysis in 12 coccinellids, //leis indica, /J,\yllohora hisoctonofafa, cheilomenes sexmaculata, Coccinella septempunctata, Cocc:inella transversalis Harmonia octomaculata, /'vficmspis discolor, Micra.,pis yaswnafsui, AJidenta misera, Epilaclma septima. l:JJi/ac:hna pusillanima and Epilachna vigintioctopuncfafa showed three amino acids alanine, lysine and glycine present in high concentration in each species. Aspartic acid and glutamic acid were absent in four species of the Epilachninea. Qualitative variations of other amino acids were found from species lo species. The highest number of amino acids (11) was identified in C. septempuncfata and C. trcmsversalis and the lowest number of amino acids (8) were detected in [,;. septima. The present chromalographical analyses showed the qualitative variations in amino acid contents from species to species. So it might be assumed that the 11011 overlapping measurements and ratios of chromosome in different species as well as the variations of amino acids composition have effect 011 cytogenetics of ladybird beetles.