Prevalence of a trypanosomatid in the southern green stink bug, Nezara viridula

The southern green stink bug, Nezara viridula (L.), and certain of its host plants were examined to determine the prevalence and biological characteri stics of an intestinal trypanosomatid. Promastigotes with short (less than or equal to 17.5 mu m excluding flagellum) and long forms (greater than or equal to 25.0 mu m) usually infected < 50% of the bugs before August and > 50% (maximum 95%) during August-October, but prevalence was not host-densit y dependent. The flagellate was detected in adults and in all nymphal insta rs, at all sampling sites where at least 10 bugs were captured, and in bugs from all host plants sampled (soybean, red clover, vetch). Of bugs with fl agellates, 27% were heavily infected (> 20 flagellates per 160x microscope field). Weights of infected and uninfected adults did not differ. Live flag ellates were detected in bug feces and in one stem of red clover. When bugs were fed soybean pods, tomatoes, or snap beans in the laboratory, only onc e were flagellates detected in plant tissue (snap beans). The flagellate wa s cultured in modified Medium 199. This flagellate is prevalent in N. virid ula populations in Louisiana and apparently does not cause significant path ological effects in N. viridula or its host plants, including soybean.