Duration of different developmental stages, mortality rate and adult longevity of rice grain bug Paraeucosmetus pallicornis (Dallas) on rice Oryza sativa (L.) and string beans Vigna sesquipedalis (L.) under controlled condition

Abstract

Paraeucosmetus pallicornis Dallas, locally known as Rice grain bug (RGB) is considered a new pest of rice in the Philippines. Originally RGB is a pest attacking string beans which is commonly planted along the bunds of rice field. This study was conducted to be able to establish the effect of string beans and rice plant on the duration of each developmental stage and adult longevity P. pallicornis Dallas under controlled condition. The duration of egg incubation and adult longevity of RGB both on rice and string beans in laboratory and screenhouse were not significant. Although there were nymphal instars that were found to be significantly different, it does not affect the total developmental period of RGB on rice and string beans under laboratory conditions. In the screenhouse, the total development period of RGB was significant on rice and string beans wherein RGB reached adult stage on the average of 30.75 days on rice plants compared to an average of 43.59 days those on string beans. This suggests the possibility that a second generation of RGB will be produced by the new batch of RGB adults bred on rice plants. Considering that the reproductive to ripening phase of rice is about 65 days, the duration of this phase could accommodate a second generation of RGB nymphs and adults. Percent mortality of RGB in rice and string beans was 23.33% under laboratory condition while in screenhouse, 76.66% was recorded in rice and 55% in string beans.