The importance of long‐term post‐release studies in classical biological control: Insect–plant monitoring and public awareness of water hyacinth management ( Pontederia crassipes ) in Dique Los Sauces, Argentina

FALTLHAUSER, ANA C.; JIMÉNEZ, NADIA L.; RIGHETTI, TOMAS; VISINTIN, ANDRÉS M.; TORRENS, JAVIER; SALINAS, NICOLÁS A.; MC KAY, FERNANDO; HILL, MARTIN; CORDO, HUGO A.; SOSA, ALEJANDRO J.

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA

WILEY-BLACKWELL PUBLISHING, INC

Año: 2023 vol. 171 p. 965 - 977

0013-8703

Several components of classical biological control (CBC) programmes are necessary to assess the success of the management strategy (e.g., post-release monitoring) and also help prevent reintroductions or resurgences of invasive species (e.g.,public awareness). Water hyacinth, Pontederia (= Eichhornia) crassipes (Mart.) Solms(Pontederiaceae) is an aquatic plant naturally distributed in the north-eastern regionof the Del Plata basin in Argentina. In the 1960s it was introduced into the Dique LosSauces reservoir located outside of its native range in La Rioja Province, in westernArgentina, where it became invasive. The natural enemy, Neochetina bruchi Hustache(Coleoptera: Curculionidae), was intentionally introduced in 1974 to control the weed.To assess the success of this CBC programme, a long-term post-release study was conducted. Between 1965 and 2023, we monitored plant coverage, estimated N. bruchidensities, and quantified the associated damage by reanalysing previously publisheddata and incorporating new sampling. We also conducted an online survey to analysepublic knowledge and perception about this programme. Water hyacinth coveragefluctuated from its first record in 1965 (maximum coverage 90%) until the control ofgerminated plants (coverage 0%) in 2018. The plant decline was accompanied by anincrease in the weevil population. In our survey, out of 325 respondents only a smallgroup of mostly middle-aged and elderly people knew that the restoration had beenachieved through a management strategy and even fewer were aware of the biocontrol approach taken. Respondents who had a positive approach to biological controlwere more aware of the management plan than respondents who had neutral or negative opinions. Neochetina bruchi has played a key factor in the control of P. crassipes.The intrinsic dynamics of these populations, the dormant seed bank, and the lack ofpublic awareness support the need for long post-release evaluations including outreach campaigns to make a sustainable successful management programme.