Release and initial establishment of a seed-feeding weevil Cissoanthonomus tuberculipennis, a biological control agent for balloon vine Cardiospermum grandiflorum in South Africa

SIMELANE D. O. ; KHETANI V. M. ; FERRUCCI M.S.

Cape Town

Simposio; XIV International Symposium on the biological control of weeds; 2014

Agricultural Research Council

After 10 years of research, approval to release a seed-feeding weevil Cissoanthonomus tuberculipennis Hustache (Coleoptera: Curculinodae) against balloon vine Cardiospermum grandiflorum SW. (Sapindaceae) in South Africa was granted by the Department of Agriculture, Forestry and Fisheries in July 2013. Over 400 C. tuberculipennis, ranging from larval to adult stages, were collected from the native range in Corrientes province of Argentina in March 2013. Field release of the weevil commenced in August 2013 in South Africa, and since then over 450 C. tuberculipennis adults have been released at nine (9) sites located in KwaZulu-Natal (KZN), Limpopo and Gauteng provinces, with fifty adults released per site. Of these, initial establishment has been recorded at eight sites in KZN and Gauteng, with seed predation by the weevil ranging from 5 to 30% per site. Seed predation by C. tuberculipennis was also conducted in an open-field in the native range to determine the contribution of this weevil to seed destruction in relation to other seed feeders in the native range. Cissoanthonomus tuberculipennis alone destroyed up to 44% of seeds per site despite competitive interaction with other seed-attacking insects in the native range. Lack of seed-feeding competitors of C. tuberculipennis on C. grandiflorum in South Africa is likely to increase the reproductive output of this weevil and thereby exacerbate seed destruction.