Effect of supply and demand of phloem sugar on the proportion of brachypterous forms of the rice pest Nilaparvata lugens Stål (Hemiptera: Delphacidae).

The sugar supplied by rice and the demand by N. lugens can affect the proportion of brachypterous forms in a population. Experiments were conducted to estimate the food ingestion by N. lugens per capita, to determine total food demand in a rice field, and to find the relation of food supply to the proportion of the brachypterous form. The results revealed that the sucrose content tended to decrease with the age of rice. However, the food demand by the N. lugens population dramatically increased in 40–89-day-old rice. The proportion of sugar supply to insect demand decreased as the insect population increased. The relative abundance of short-wing form insects increased when the ratio of sugar supply to insect demand was ≥0.02, but was decreased when the ratio was lower than 0.01. These results are useful for predicting N. lugens dispersal related to sugar supply in rice fields. [ABSTRACT FROM AUTHOR]