The Biology and parasitoids of Cnaphalocrosis medinalis guenee and screening of selected rice varieties against this pest /
Eliseo H. Batay-an.
- Los Baņos, Laguna : University of the Philippines, 1982.
- 93 pages : illustrations ; 28 cm.
Thesis (M.S. - - Entomology) University of the Philippines, College, Laguna.
Includes bibliographical references.
BATAY-AN, ELISEO HABON, University of the Philippines at Los Banos, March, 1982. The Biology and Parasitoids of Cnaphalocrosis medinalis Guenee and Screening of Selected Rice Varieties Against this Pest. Major Professor: Dr. Eliseo P. Cadapan
The life history, feeding habits, seasonal abundance, parasitoids of Cnaphalocrosis medinalis guenee and screening of selected rice varieties against this pest were in- vestigated under Midsayap conditions.
The total developmental period of the rice leaf folder from egg laying up to moth emergence was observed to be 31.95 days on the average. The incubation, larval, prepupal and pupal period lasted for an average of 3.17, 19.43, 1.85 and 7.5 days, respectively.
Only one peak period on moth population was recorded, They were most abundant during the later part of March, least abundant during the early and middle parts of April and June, early part of September and later part of October.
It was fairly abundant in May, July, August, November and December to February.
Three Hymenopterotis and one Dipterous parasitoids were recovered from the larvae and pupae of Cnaphalocrosis medinalis Guenee. Two species of Ichneumonids, Trichoma cnaphalocrosis Uchida and Temelucha sp., one Encyrtid, Pentalitomastix sp. and one Phorid, Megaselia scalaris Loew were also found.
Out of the 68 varieties and selections screened, only 4 were resistant, 43 moderately resistant, 19 moderately susceptible and 2 susceptible based on the percentage damage as compared to susceptible TNI.
Preference or non-preference and antibiosis were mainly the mechanisms of resistance to C. medinalis Guenee. The non-preferred varieties and selections received lesser number of eggs per plant than susceptible varieties and the survival and development of the larvae caged on resistant selections and varieties were considerably lower than susceptible ones. A significant positive correlation was noted on the number of eggs oviposited per plant with leaf density but not with plant height. These illustrate that resistant varieties are not only unsuitable as food but also affect the development of the larvae.