Cytogenetics of orb-weaving spiders (Neoscona Species) sampled from a corn field at San Isidro, San Luis, Batangas

Date

4-2004

Degree

Bachelor of Science in Biology

Major Course

Major in Ecology Genetics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Adelina A. Barrion

Abstract

Net sweeping and handpicking collections of spiders from the corn field at San Isidro, San Luis Batangas from July to September revealed the dominance of orb-weavers particularly Neoscona species. Based on the morphological features. the .Veoscona species consisted of Neoscona punctigera (Doleschall) and an unknown species. Neoscona sp. Lacto-aceto-orcein squashes of the abdominal reproductive tissues revealed the meiotic cells with chromosomes. Cytogenetics of the two species consist of the chromosomal features during the different stages of the first meiotic division. Different stages of first meiosis, which were identified and characterized in the two spider morphs of If punctigera were normal. No structural or chromosomal aberrations were observed. The karyogram of the premetaphase chromosomes of N. punctigera and ,Veoscona .sp. revealed diploid chromosome numbers of 2n=16 and 2,19, respectively. Two meiotic indices were obtained from N. punctigera: 55.78% for the black morph and 49.63% for the gray morph. At 0.05 % level of significance, no significant difference was found among the values obtained for the black ang gray morphs of the corn orb-weaver, punctigera. Neoscona sp. exhibited a meiotic index of 54. 7%. The relative lengths of chromosomes ranged from 0.063 to 0.227 in N. punctigera and 0.068 to 0.181 in Neoscona sp.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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