Comparative Development of Rice Grain Bug, Paraeucosmetus pallicornis (Dallas 1852) (Hemiptera:Lygaeidae) on Common Weeds in Ricefields of Agusan del Norte, Philippines

Abstract

Alternate host plants are important factors in the development of pest management strategies to reduce the infestation in rice. The development of the rice grain bug, Paraeucosmetus pallicornis (Dallas 1852) was studied on select weeds: Echinochloa crus-galli, E. glabrescens, Cyperus iria, C. difformis, and Vigna sesquipedales under laboratory and screenhouse conditions. Results revealed that all treatments were capable of supporting the growth and development of the rice grain bug from egg to adult stage. Variations in egg
incubation periods were recorded (V. sesquipedales=6.67 days; E. crus-galli=7.33 days; C. iria and E. glabrescens = 7.66 days; C. difformis = 9.0 days). The newly hatched nymphs of P. pallicornis were reddish in color and had enlarged abdomen upon feeding after a few days. The nymphs passed five nymphal instars in 32.1 days in V. sesquipedales, 28.1 days in C. iria, 27.1 days in C. difformis, 25.4 days in E. crus-galli, and 23.0 days in E. glabrescens. The pre-oviposition periods of the newly emerged female adults were 6.3 days in C. difformis; 6.0 days in C. iria and V. sesquipedales; 5.67 days in E.crus-galli; and 5.0 days in E. glabrescens. Results of this study could be used as basis for the formulation of appropriate rice crop management. The tested weeds provide refugia, hence, should be managed to prevent pest infestations.