Author
Presentig: Alejandro Sosa
Fundación para el Estudio de Especies Invasivas
Hurlingham, Buenos Aires
Laura Varone
lauvarone@fuedei.org
Fundación para el Estudio de Especies Invasivas
Hurlingham, Buenos Aires
Coauthors
Sol Ailén, Bovina, Fundación para el Estudio de Especies Invasivas, Hurlingham, Argentina
Melissa Smith, USDA-ARS Invasive Plant Research Laboratory, Fort Lauderdale, FL, United States
Abstract
Waterhyacinth is one of the world’s most problematic aquatic weeds, and Megamelus scutellaris (Hemiptera: Delphacidae) has been successfully used as a biological control agent in several invaded regions. However, little is known about the parasitoid complex affecting this species in their native range. This study investigates the natural enemies associated with M. scutellaris through systematic field surveys, evaluating their diversity, abundance, parasitism rates, and population dynamics. Understanding these interactions is key to improving the effectiveness and sustainability of biological control programs. Monthly samplings were conducted from October 2024 to March 2025 in the Paraná River Delta, Argentina, to collect M. scutellaris and study their parasitoids. Insects were aspirated and reared in the lab to monitor parasitoid emergence. Egg parasitism was assessed using sentinel eggs from lab-reared M. scutellaris, exposed in the field. A total of 3,490 individuals of M. scutellaris were collected. Parasitism of nymphs and adults remained low (<15%), involving Drynidae and Strepsiptera. From sentinel eggs, 85 parasitoids (~3%) were recovered, with seasonal shifts in species composition. The most abundant egg parasitoid species were Anagrus empanadus (Mymaridae), and a so far unidentified Chalcidoidea morphospecies. Future efforts will improve sampling design, expand site coverage, and apply genetic tools for accurate parasitoid identification and community analysis.
keywords
parasitoid diversity
field surveys
egg parasitoid
Highlights
Native parasitoids of M. scutellaris are diverse but show low parasitism rates.
Seasonal shifts were found in egg parasitoid composition on sentinel eggs.
Field surveys reveal key data to enhance long-term biocontrol strategies.