Diversity of insect pests and natural enemies associated with PSB RC72H (Mestizo Hybrid) rice variety in Ilocos Norte

Issue Date

10-2004

Abstract

The study was conducted in Dingras and Piddig, Ilocos Norte during the dry season of 2003. It aimed to monitor the species of insect pests and natural enemies associated with rice variety PSB RC72H, determine their abundance, estimate the damage caused by the major insect pests and determine the factors affecting their infestation Insect population were assessed through visual count on the plant, handpicking, use of blower vac machine, and net sweeping during the vegetative, booting, and milk stages of the crop. In Dingras, 18 taxa of insect pests were found associated with the crop. The most abundant was a carabid species found during the three crop growth stages monitored. This was followed by Cnaphalocrosis medinalis (Guenee) and Epiny drid species at vegetative stage, C. medinalis and Sesamia inferens (walker) (booting), and Leptocoriza eratorius (Fabricus) and S. inferens (milk stage). Twenty-two (22) natural enemy taxa were observed, 11 insects and 11 spiders. The most abundant insect taxa were Micrapis sp. (vegetative-milk stages) followed by Euborellia stali (Dohrn) (booting) and Scarabaiedae species (vegetative), while the most abundant spider was a Linyphiid species during the booting and milk stages followed by Pardosa sp. and P. pseudoannulata (Boesenberg and Strand) during the vegetative stage. In Piddig, 20 taxa of insect pests were observed. The most abundant were Lygalid species followed by S. inferens and chilo suppressalis (Walker)(Booting) and Carabid species (Milk and vegetative). Twenty-six (26) taxa were of natural enemies were observed, 14 of which were insects and 12 were spiders. Of the insect taxa, the most abundant were micrapis sp. (booting and milk), Formieid species (booting) and E. stali (vegetative) while the most abundant spiders were Lyniphiid species (booting and vegetative), Theridiid species (booting and milk) and P. pseudoannulata (booting). The damage caused b y C. medinalis, S. inference; and C. suppressalis were negligible. The population densities of natural enemies were consistently higher than that of the insect pests in all stages of plant growth, except during the vegetative stage in dengras. The results strongly indicated that the high density of natural enemies, therefore, is an effective strategy in managing insect pests. The abiotic factors like temperature, rainfall, and wind velocity did not affect the insect pest population

Source or Periodical Title

Philippine Entomologist

ISSN

0048-3753

Volume

18

Issue

2

Page

164-165

Document Type

Article

Frequency

semi-annually

Language

English

En – AGROVOC descriptors

LEPTOCORISA ORATORIUS; CARABIDAE; SESAMIA INFERENS; ARANEAE; CNAPHALOCROCIS MEDINALIS; ORYZA SATIVA; PLANT PESTS; DEVELOPMETAL STAGES; DAMAGE; PHILIPPINES

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