Reproductive cycles and behavior of rice black bug (Scotinophara coarctata (Fab.)) (Hemiptera: Pentatomidae), as influenced by rice phenology: implications to its flight and aggregation behaviour
2018
Ramo, D.C.
This study was designed to offer a possible explanation of the flight and aggregation behavior of the rice black bug (RBB), Scotinophara coarctata by linking these behaviors to the reproduction of the bug. Greenhouse and field studies were conducted to determine if oviposition of RBB is confined to certain phenological stage of rice and if this oviposition preference is reflected in the population dynamics of rice black bug over two cropping seasons. Behavioral experiments showed that RBB discriminated against the seedling stage as oviposition site. The significantly higher number of eggmasses laid on the booting and soft dough stages of rice, as well as the number of visits and the length of time RBB stayed on these stages compared to other stages seemed to indicate a preference to these phenological stage. It was evident from the age structure, population dynamics and monitoring of the reproductive status of RBB over two croppings that individuals arriving in the rice field were mostly immature and unmated, and that only one reproductive cycle was completed in a cropping season. Based on the patterns observed in the field and experimentation, reproductive cycles and oviposition behavior of RBB are apparently influenced by the phenology of rice. Because of this specific requirement in oviposition, a wide scale absence of appropriate growth stage of rice for an extended period of time could be a driving factor that leads to flight involving a large number of individuals. Further studies must be conducted to test this hypothesis.
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