Biological control of aquatic weeds: seeking sustainable solutions for the recovery of urban wetlands in northeastern Argentina.

BERTUCCI, SABRINA; SOSA, A.J.; FRANCESCHINI M. CELESTE

Puerto Iguazú

Simposio; XVI International Symposium on biological control of weeds, Session Prospects for weed biological control in South America; 2023

FuEDEI y CERZOS (CONICET), International Organisation for Biological Control (IOBC)

Urban wetlands are a critical part of urban developments because of the ecosystem servicesthey provide. However, many of them are seriously affected by the presence of invasiveplants, as is the case of several urban ponds in northeastern Argentina (NEA). Increases inthe biomass of these weeds produce physical and chemical alterations that affect waterquality. Also, because of their high reproductive capacity, these weeds displace the rest ofthe plants, and associated fauna, that coexist with them. This leads to a loss of biodiversityand habitat complexity that alters the structure and functioning of the invaded wetlandsystems. From an urban point of view, weed invasions represent a relevant problem, sincethey affect flood buffering capacity. In Argentina, the most harmful aquatic weeds in theworld are represented, including, for example, the water lettuce Pistia stratiotes (Araceae).Different management strategies are often applied to mitigate the invasion; however, theyrarely achieve sustained control. Mechanical control can be ineffective for large areas andis highly costly since fragmentation or seed banks prevent this control from lasting overtime. Similarly, chemical herbicide control is also unsuccessful and environmentallyunsustainable because it depends on continuous application to control reinfestations, andmay be harmful to human health or to biological control agents released as part of integratedmanagement programs. In view of this scenario, a research project has been designed toapply biological control in invaded urban ponds in the NEA, through the introduction ofhighly specific herbivorous insects, as a harmless, low-cost and sustainable tool. Thisproject will be carried out in collaboration between different research groups in Argentina(HeCoB-CECOAL and FuEDEI) and is intended to: (a) assess the current impact of theweed Pistia stratiotes in different ponds of the NEA, (b) perform bioprospecting of naturalenemies and potential biocontrol agents of the weed in the field, and (c) conductexperiments to determine the optimal density of agents needed to achieve control. Thisstudy will generate knowledge that will contribute to the reduction of P. stratiotes invasionlevels and the consequent restoration of the ecosystem balance.