How about Cornops aquaticum (Orthoptera: Acrididae) in its native area in Del Plata wetlands? Ecology and biology of a new control agent of water hyacinth

FRANCESCHINI MARIA CELESTE; DE WYSIECKI MARÍA LAURA; SOSA ALEJANDRO

Ciudad Autónoma de Buenos Aires

Congreso; Marine and Invasive freshwater species: ecology, impact and management; 2016

Aquatic Ecosystems, health and management Society

Cornops aquaticum is a native grasshopper associated with Pontederiaceae, especially water hyacinth, Eichhornia crassipes. This insect is being studied as a biological control agent of water hyacinth, which becomes the most important aquatic weed around the world. The aim of this research was: (a) assess life cycle of C. aquaticum, to determine the number of nymphal instars of this species; (b) evaluate variation in abundance and the age structure of C. aquaticum population living on two host plants: E. crassipes and E. azurea; (d) assess the performance and feeding preference of each age category of C. aquaticum in crops and wetland plants in relation to the host plant E. crassipes; (e) discuss risk and benefits of C. aquaticum as a potential biological control agent in the context of ecology and biology of this grasshopper in native areas. Our results showed that males of C. aquaticum had five instars whereas females had five or six instars. Monthly samplings of populations from February 2004 to April 2006 showed that adults were present during all sampling dates, whereas first instar nymphs were absent during the coldest months. Total abundance reached up to 96 ind. captured/min on E. azurea and 61 ind. captured/min on E. crassipes during summer months. Performance feeding test show that most individuals of C. aquaticum had high survival on E. crassipes. In some non-host plants, high survival of grasshoppers was also observed, except for first instar nymphs. Ovipositions were registered in E. crassipes and in some non-host plants, but only eggs laid in E. crassipes were endophytic and viable. This grasshopper showed high feeding preference to E. crassipes during the choice tests. Our results confirm the high specificity of C. aquaticum to E. crassipes, hence this species have potential to be used as bio controller of water hyacinth.