Abundance across seasons and early impact of the florivorous weevil Anthonomus santacruzi (Curculionidae) on Solanum mauritianum (Solanaceae) in KwaZulu-Natal Province, South Africa

Publication date: Available online 7 March 2018 Source:Biological Control Author(s): Kelby English, Terence Olckers The florivorous weevil Anthonomus santacruzi Hustache (Coleoptera: Curculionidae) was first released in South Africa in 2009 to reduce fruiting by the invasive Solanum mauritianum Scopoli (Solanaceae). Additional releases during 2011-2014 achieved widespread establishment in KwaZulu-Natal Province, notably in its warmer coastal regions. The aims of this study were to determine whether A. santacruzi abundance: (i) varied monthly at coastal versus inland sites; (ii) was influenced by floral availability and the numbers of ants associated with S. mauritianum inflorescences and; (iii) negatively affected the weed’s fruit production. Sampling over a 12-month period indicated that A. santacruzi abundance varied seasonally across coastal and inland sites, with populations consistently peaking in the austral autumn months and declining during winter. Although A. santacruzi numbers were significantly positively correlated with floral availability in the previous month, <10% of available flower buds were infested monthly by weevil larvae. Significant negative correlations between weevil numbers and fruit set recorded two months later was likely caused by the abscission of ripe fruit, rather than feeding damage. While ant abundance on S. mauritianum inflorescences was positively linked with numbers of mature fruit, there was no evidence of any interference wit...

Source: Biological Control - March 8, 2018 Category: Biology Source Type: research