A Physiological Age-Grading System forNeochetina eichhorniae(Warner) (Coleoptera: Curculionidae), a Biological Control Agent of Water Hyacinth,Eichhornia crassipes(Mart.) Solms.

1997 ◽  
Vol 9 (2) ◽  
pp. 89-105 ◽  
Author(s):  
Michael J. Grodowitz ◽  
Ted D. Center ◽  
Jan E. Freedman
Keyword(s):  
Biological Control ◽  
Water Hyacinth ◽  
Eichhornia Crassipes ◽  
Biological Control Agent ◽  
Control Agent ◽  
Physiological Age ◽  
Grading System ◽  
Age Grading

The pathogenicity of an Australian isolate of Acremonium zonatum to water hyacinth, and its relationship with the biological control agent, Neochetina eichhorniae

1987 ◽  
Vol 38 (1) ◽  
pp. 219 ◽  
Author(s):  
JC Galbraith
Keyword(s):  
Biological Control ◽  
Water Hyacinth ◽  
Biological Control Agent ◽  
Control Agent ◽  
Control Programme ◽  
Australian Isolate ◽  
Free Moisture ◽  
Neochetina Eichhorniae ◽  
Dry Conditions ◽  
The Individual

The first description of Acremonium zonatum on water hyacinth in Australia is made. Its pathogenicity was studied as part of the search for a microorganism already present in Australia which could be developed as a mychoherbicide to supplement the arthropod biological control programme in this country. Following inoculation with A. zonatum, extensive leaf infections developed, favoured by injury and free moisture, but new leaves continued to form. Feeding by the weevil, Neochetina eichhorniae, increased infection by A. zonatum in relatively dry conditions, but it is unlikely that this was due to feeding scars acting as ports of entry. A. zonatum spores were transported on the feet and in the digestive tract of the weevil. The growth of infected plants, estimated by standing crop, was reduced by 49% compared to the control. A further decrease occurred in infected plants infested by weevils, but the total reduction in growth was not equal to the sum of the individual effects of fungus and weevil. Infection did not develop in 15 other plant species inoculated with the Australian isolate of A. zonatum. Although not a virulent pathogen, A. zonatum has some favourable characteristics for consideration as a mycoherbicide and has not appeared antagonistic to N. eichhorniae in these studies. Its role probably lies in exerting a chronic stress on plants already under attack by arthropod biological control agents.

Effects of salinity and nutrients on water hyacinth and its biological control agent, Neochetina bruchi

Hydrobiologia ◽  
2020 ◽  
Vol 847 (15) ◽  
pp. 3213-3224 ◽  
Author(s):  
Emily Bick ◽  
Elvira S. de Lange ◽  
Cindy R. Kron ◽  
Lorena da Silva Soler ◽  
Jessie Liu ◽  
...  
Keyword(s):  
Biological Control ◽  
Water Hyacinth ◽  
Biological Control Agent ◽  
Control Agent

Population regulation of a classical biological control agent larval density dependence inNeochetina eichhorniaeColeoptera Curculionidae, a biological control agent of water hyacinthEichhornia crassipes

2006 ◽  
Vol 96 (2) ◽  
pp. 145-152 ◽  
Author(s):  
J.R.U. Wilson ◽  
M. Rees ◽  
O. Ajuonu
Keyword(s):  
Biological Control ◽  
Density Dependence ◽  
Water Hyacinth ◽  
Biological Control Agent ◽  
Larval Density ◽  
Nutrient Status ◽  
Classical Biological Control ◽  
Control Agent ◽  
Control Measures ◽  
Nutrient Concentrations

AbstractThe release of classical biological control agents has reduced the economic, environmental and social problems caused by water hyacinth,Eichhornia crassipes; however, additional control measures are needed in some locations. Water hyacinth plants were treated with different densities of eggs of the weevilNeochetina eichhorniaeWarner, one of the main control agents, under different nutrient regimes in a controlled experiment. Plants were destructively sampled and the development ofN. eichhorniaewas assessed. The survival of first and second instars declined as larval density increased. Plant nutrient status did not directly affect the mortality rate of larvae, but at higher nutrient concentrations larvae developed faster and were larger at a given developmental stage. It is argued that the density dependence operating inN. eichhorniaeoccurs through an interaction between young larvae and leaf longevity. Consequently, events which disrupt water hyacinth leaf dynamics, e.g. frost or foliar herbicides, will have a disproportionately large effect on the control agents and may reduce the level of control of the host.

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