Host specificity assessment and potential impact ofMegamelus scutellaris(Hemiptera: Delphacidae) on waterhyacinthEichhornia crassipes(Pontederiales: Pontederiaceae)

Abstract

The delphacid Megamelus scutellaris Berg was evaluated for host specificity and potential impact as part of a biological control program targeting Eichhornia. crassipes. Survival and development of adults and nymphs were used as metrics with no-choice, two-choice, nymph transfer, and sustainability tests conducted under quarantine conditions. A total of 69 plant species were tested including 12 from the Pontederiaceae (including E. crassipes). Additionally, 27 native and 5 exotic associated wetland species and 11 economic species were tested. Megamelus scutellaris exhibited a high level of oviposition and developmental fidelity to E. crassipes by failing to sustain populations on any non-target test plant past the F 1 generation. Nymph transfer tests which simulated potential spill-over events found that survival was virtually non-existent on associated wetland plants, regardless of taxonomic relatedness, including on Pontederia cordata, an important and widespread native species. Eichhornia crassipes plants exposed to two consecutive generations of feeding produced 66.9% less biomass and 73.4% fewer leaves than those in the controls. We conclude that Megamelus scutellaris is safe to release on E. crassipes in the United States.

Current levels of suppression of waterhyacinth in Florida USA by classical biological control agents

“…Recently, there has been a renewal of biological control programs in the USA that target E. crassipes which makes the evaluation of new agents problematic because of the presence of the existing agents. For example, and although observations of this insect are not presented here, a new agent, Megamelus scutellaris Berg (Hemiptera: Delphacidae), has been developed and was released in Florida in 2010 with the goal of increasing the suppression on the weed (Tipping et al, 2011). Conducting realistic field evaluations of the current agents would provide insight into the performance of newly released agents by disentangling their impacts from their successors.…”

Feeding behavior and spatial distribution of two planthoppers,Megamelusscutellaris(Delphacidae) andTaosalongula(Dictyopharidae), on water hyacinth

“…In the field, most of the newly hatched nymphs aggregate in the basal part of the petioles close to the water, along with populations of older nymphs and winged and wingless adults (Sosa et al 2005). It is highly specific to water hyacinth (Sosa et al 2007b) and it was recently released as a biological control agent for this weed in Florida, USA (Tipping et al 2011). Adults of M. scutellaris were collected, from water hyacinth populations along the Paraná River in Argentina, to establish a laboratory culture.…”

“…For example, the planthoppers Megamelus scutellaris Berg (Delphacidae) and Taosa (Cuernavaca) longula Remes Lenicov (Dictyopharidae) feed and reproduce on the invasive aquatic weed, water hyacinth, Eichhornia crassipes (Martius) SolmsLaubach (Pontederiaceae), and both are considered potential biocontrol agents of this weed. Several studies have been conducted on both species, including taxonomy (Sosa, Remes Lenicov, Mariani, and Cordo 2004;Sosa, Remes Lenicov, and Mariani 2007a;Remes Lenicov and Hernández 2010), ecology (Hernández, Sacco, and Cabrera, in press) and host specificity (Sosa, Cordo, and Sacco 2007b;Tipping, Center, Sosa, and Dray 2011). Both species negatively affect biomass and seed production, increase leaf chlorosis, and ultimately increase the rate of senescence under laboratory conditions (Sosa et al 2007b;Sacco, Cabrera, and Hernández, unpublished data).…”

Adaptability of two weevils (Neochetina bruchi and Neochetina eichhorniae) with potential to control water hyacinth in the Rift Valley of Ethiopia

“…It is environmentally friendly and has successfully reduced infestations in many African countries (Cilliers et al, 2003;Hill et al, 1999;Mbati and Neuenschwander, 2005). Among the seven arthropod agents released worldwide (Harley, 1990;Julien et al, 1999;Tipping et al, 2010Tipping et al, , 2014, two weevils, Neochetina eichhorniae (Warner) and Neochetina bruchi Hustache (Coleoptera: Curculionidae), are the most effective (Center et al, 1999;Center and Van, 1989;DeLoach and Cordo, 1976a). These two weevil species have been released on water hyacinth in 30 (N. bruchi) and 27 (N. eichhorniae) countries, respectively (Center et al, 2002).…”