Mind the gap: the delayed recovery of a population of the biological control agent Megamelus scutellaris Berg. (Hemiptera: Delphacidae) on water hyacinth after winter

2020 ◽  
Vol 111 (1) ◽  
pp. 120-128 ◽  
Author(s):  
Benjamin E. Miller ◽  
Julie A. Coetzee ◽  
Martin P. Hill
Keyword(s):  
Biological Control ◽  
Water Hyacinth ◽  
Biological Control Agent ◽  
Population Decline ◽  
Growing Season ◽  
Control Agent ◽  
Population Recovery ◽  
Control Effort ◽  
Developmental Threshold ◽  
Winter Temperatures

AbstractCold winter temperatures significantly affect the biological control effort against water hyacinth, Pontederia ( = Eichhornia) crassipes Mart. (Pontederiaceae), in more temperate regions around the world. The population dynamics of the planthopper Megamelus scutellaris Berg. (Hemiptera: Delphacidae), a newly released biological control agent of water hyacinth, were recorded on the Kubusi River in the Eastern Cape Province (South Africa) over 15 months to determine the population recovery post-winter. Megamelus scutellaris incurred a severe population decline at the onset of winter when the water hyacinth plants became frost damaged. The combined effect of a population bottleneck and low minimum winter temperatures (6.12°C) below the agent's lower developmental threshold (11.46°C) caused a post-winter lag in agent density increase. Subsequently, the maximum agent population density was only reached at the end of the following summer growing season which allowed the water hyacinth population to recover in the absence of any significant biological control immediately post-winter. Supplementary releases of agents from mass-reared cultures at the beginning of the growing season (spring) is suggested as a potential method of reducing the lag-period in field populations in colder areas where natural population recovery of agents is slower.

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.

scholarly journals Correction to: Effects of salinity and nutrients on water hyacinth and its biological control agent, Neochetina bruchi

Hydrobiologia ◽  
2020 ◽  
Vol 847 (15) ◽  
pp. 3225-3225
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

Effects of photoperiod on induction of diapause in Feltiella acarisuga (Diptera: Cecidomyiidae)

2002 ◽  
Vol 134 (1) ◽  
pp. 69-75 ◽  
Author(s):  
D.R. Gillespie ◽  
D.M.J. Quiring
Keyword(s):  
Biological Control ◽  
British Columbia ◽  
Biological Control Agent ◽  
Gall Midge ◽  
Growing Season ◽  
Spider Mites ◽  
Control Agent ◽  
Leaf Surfaces ◽  
Low Incidence ◽  
Predatory Gall Midge

AbstractLarvae of the predatory gall midge Feltiella acarisuga (Vallot) diapaused as prepupae in tightly woven, brown, silk cells on leaf surfaces. Photoperiod alone, at day lengths from 16 to 8 h did not induce diapause at either 20 or 25 °C. A low incidence of diapause was induced by a combined photoperiod and thermoperiod of an 8-h day at 25 °C and a 16-h night at 15 °C. The incidence of diapause was higher under these conditions if the larvae were fed diapausing spider mites, Tetranychus urticae (Koch) (Acari: Tetranychidae). Because F. acarisuga only diapauses at daylengths equivalent to mid-winter, when its prey, T. urticae, is also in diapause, it can be used as a biological control agent for T. urticae in British Columbia greenhouses throughout most of the growing season.

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