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Asian Journal of Agriculture and Development (AJAD) - Call for papers!

The Effect of Some Morphological Characters of Selected Cotton Strains on Cotton Bollworm, Helicoverpa Armigera Hubner

(Philippines), Master of Science in Entomology (University of the Philippines Los Baños)

Thesis Abstract:

The effectsof hirsute, glabrous, glandless, glanded, nectaried, and nectariless characters of six selected cotton strains on Helicoverpa armigera were tested under laboratory, cage, and field conditions.
 

In the laboratory, H. armigera moths generally preferred to oviposit on growing tips. Growing tips of Alcala Glandless and Nectariless 1215-SR-2 were the most and the least prefered for oviposition, respectively. On the other hand, squares were the most preferred for larval feeding, where Alcala Glandless was the most preferred while Nectariless 1215-SR-2 the least.

In the cage test, the growing tips offered the most favored site for oviposition, followed by the squares. In the field, Sea Island (hirsute) was the most preferred host for oviposition followed by Alcala Glandless, Stoneville 213 (nectaried). Deltapine 16 (normally glanded). Nectariless 1215-SR-2, and REBA P279 (glabrous) but Nectariless 1215-SR-2 and REBA P279 exhibited the least damaged squares and bolls, repectively. On the other hand, Sea Island had both the highest damaged squares and bolls, indicating that the glabrous and nectariless characters of cotton strains were outstanding resistant factors against H. armigera.

H. armigera moths preferred to oviposit on 68-day-old Sea Island than at 83-day-old REBA P279.

Seventy-nine-day-old Sea Island and 99-day-old REBA P279 harbored the highest and the lowest nuber of larvae, respectively.

Glabrous REBA P279 gave the highest yield while Sea Island hirsute produced the lowest. There was an inverse relationship between or among seed cotton yield and number of bollworm eggs and larvae, and percent damaged squares and bolls. Direct relationship existed between or among number of eggs and larvaem and percent damaged squares and bolls.