Introduction of parasitoids for the control of the cassava mealybug Phenacoccus herreni (Hemiptera : Pseudococcidae) in north-eastern Brazil

The mealybug Phenacoccus herreni Cox & Williams causes considerable damage to cassava Manihot esculenta Crantz. Field surveys conducted between 1988 a nd 1994 indicated the mealybug was present in 57 municipalities in six Stat es in north-eastern Brazil, in some places reaching high levels of infestat ion. Several native natural enemy species were found associated with the pe st in Brazil. Exotic encyrtid parasitoids were imported and released in fie lds in the States of Bahia and Pernambuco. Apoanagyrus diversicornis (Howar d) was introduced from Colombia, and Acerophagus coccois Smith, and Aenasiu s vexans (Kerrich) were introduced from Venezuela. By the end of 1996, a to tal of 35,930 parasitoids had been released. In Bahia, Apoanagyrus diversic ornis was recovered 130, 234, 304 and 550 km from its release site after 6, 14, 21 and 33 months, respectively. Acerophagus coccois was recovered at 1 80 km from its release site nine months after release. Aenasius vexans, how ever, did not disperse at all despite being consistently recovered at its r elease site. In Pernambuco, 9010 parasitoids were released from October, 19 95 onwards. Acerophagus coccois and Aenasius vexans were recovered up to 40 km from the release sites after three and five months of their initial rel eases, respectively. The establishment and dispersal of these parasitoids a re discussed.