Egg parasitoids of hemipteran pests of cowpea in Nigeria and Tanzania, with Special reference to Ooencyrtus patriciae Subba Rao (Hymenoptera: Encyrtidae) attacking Clavigralla tomentosicollis Stål (Hemiptera: Coreidae)

Abstract

AbstractEgg parasitoids attacking economically important pod-sucking Hemiptera on cowpea were collected in Nigeria and Tanzania. The three coreid hosts, Anoplocnemis curvipes (F.), Clavigralla tomentosicollis Stål and C. elongata Sign., and the two alydid hosts, Mirperus jaculus (Thnb.) and Riptortus dentipes (F.), form a pest complex that attacks grain legumes across Africa. Parasitoids attacking eggs of C. tomentosicollis were monitored on farmers' fields at a locality in northern Nigeria. Parasitism rose from low initial levels to maxima of 62% in 1978 and 51% in 1979. This mortality did not keep host populations below the economic injury level. The egg parasitoid complex of C. tomentosicollis was dominated by the scelionid Gryon gnidus (Nixon), while the encyrtids Ooencyrtus patriciae Subba Rao and O. kuvanae (How.) parasitised a large proportion of host eggs at times. Small numbers of Gryon fulviventris (J. C. Crawford) and the eupelmids Anas tatus spp. were reared. Observations on the biology and behaviour of O. patriciae are presented. This species occurred in both Tanzania and Nigeria and attacked all hosts studied. Rearings of all these parasitoids and also another species of Gryon, a species of Baeus and two species of Telenomus from eggs of the five species of Hemiptera are reported.