Cytogenetic effect of gamma radiation on the spermatocytes of corn earworm, Helicoverpa armigera (Hubner).

Date

3-1997

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Adelina A. Barrion

Abstract

Sixth instar larvae of the Fi male corn earworm from both irradiated (150 Grey gamma radiation) and normal parent moths were dissected and the extracted testes were fixed in freshly prepared Farmer's solution (3 parts Ethanol:1 part Glacial Acetic Acid). Lacto-aceto-orcein squash preparations of the testes from 10 Fi male larvae with normal male parents and 30 F1 larvae of irradiated male parents were done and cytologically observed under the light microscope. The cytological examination of the spermatocytes of the larvae from normal male parents showed that these underwent normal Meiosis I or reductional division. At diakinesis, a haploid number of n=31 chromosomes were counted and the mean relative lengths of the chromosomes were measured to be from 0.0226-0.0446. Also, the possible karyotype established for the Helicoverpa armigera was 30 autosomal bivalents and ZZ sex chomosomes (30AII + ZZ) for males. Thus, the males were the homogametic sex. On the other hand, examination of the spermatocytes of F1 larvae from irradiated male parents showed that all the 30 individuals cytologically investigated possessed in their spermatocytes 1-6 heterozygous reciprocal translocation chains and rings involving a varying number of chromosomes ranging from 4-38 Translocation heterozygotes usually lead to partial sterility in insects. This result then suggests the effectivity of using 150 Grey gamma radiation for the induction of varying degrees of sterility in the F1 generation and the efficiency of using reciprocal translocation as a cytogenetic marker to assess the effect of a low dose radiation on the chromosomes of the corn earworm.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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