Mirid Bugs in China: Pest Status and Management Strategies

Abstract
Over the last 10 years, mirid bugs (Heteroptera: Miridae) have evolved increasingly as an important group of insect pests in Bt-cotton agro-ecosystems in China. The government, the public and scientific researchers paid great attention to this new problem, because it may be correlated with the area wide planting of Bt-cotton. Mirid bugs belong to a group of crop insect pests found worldwide. In China, more than 20 species of mirid bugs have been detected in cotton. Mirid bugs are polyphagous insects with more than 200 species of host plants, including cotton, Chinese date, grape, apple, pear, peach and many other crops. These insects feed on terminal meristems, young squares and bolls, and various other tissues belonging to the host plant it invades. Infestation with mirid bugs results in bushy plants and abscission of squares and bolls. At high population densities, the insects cause considerable losses in host crop production. Recently, both the occurrence of mirid bugs and the damage caused by these insects has progressively increased in cotton and other host crops in China. This article briefly summarizes the current population status of these pests and management strategies to deal with the problem. In addition, the authors also discuss the future development of alternative control measures. Based on these pest management strategies, infestation levels of mirid bugs are satisfactorily suppressed and the associated insecticide use reduced compared to the conventional control program developed and used by local farmers. Chemical insecticides, however, are still widely used in mirid bug control. In order to prevent potential insecticide resistance of mirid bugs while still allowing for the development of low pesticide-residue crops, such as fruits, tea and others, some alternative environmentally-friendly measures (eg biological control with parasitic wasps or microorganisms, pest behavioural manipulation with plant volatiles or sex pheromones, and resistant crop variety) must be developed further. Additionally, in China, there are different cropping patterns, including mixed plantations of food crops and cotton, fruit trees and cotton, pastures and cotton, and so forth. In each cropping pattern, mirid bug species composition, and their overwintering location and early seasonal host plant range vary considerably. Hence, different forecasting and management programs for mirid bug population control will need to be tailored to meet specific planting patterns.