The effect of Neochetina eichhorniae and Myrothecium roridum alone and in combination for the initial biological control of waterhyacinth

Seeni Mohamed, . and Caunter I.G., . The effect of Neochetina eichhorniae and Myrothecium roridum alone and in combination for the initial biological control of waterhyacinth. pp. 133-140. ISSN 0127-6883

The waterhyacinth weevil Neochetina eichhorniae reduced net rate of leaf production of water hyacinth plants when eight and ten pairs of weevils were used. Significant reduction in rate of biomass increment was obtained only with treatment level of ten pairs of weevils. Nevertheless all treated plants recorded a net gain in biomass. Net gain in biomass is reflected in no significant size reduction as determined by longest leaf length. Myrothecium roridum at all spore concentrations tested significantly reduced biomass. Concentrations of 6 million spores/ml and above completely destroyed leaves and petioles. Weevils applied to plants lightly infected with M. roridum (1 million spores/ml) gave more effective control. Net rate of biomass increment was significantly reduced for all weevil-pathogen combinations. Net biomass however still increased with treatment levels of five and eight pairs of weevils. Treatment with ten pairs of weevils prevented any increase in biomass but failed to significantly reduce original biomass. Significant reduction in plant size was observed after four weeks for all weevil-pathogen combinations.

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Abstract

The waterhyacinth weevil Neochetina eichhorniae reduced net rate of leaf production of water hyacinth plants when eight and ten pairs of weevils were used. Significant reduction in rate of biomass increment was obtained only with treatment level of ten pairs of weevils. Nevertheless all treated plants recorded a net gain in biomass. Net gain in biomass is reflected in no significant size reduction as determined by longest leaf length. Myrothecium roridum at all spore concentrations tested significantly reduced biomass. Concentrations of 6 million spores/ml and above completely destroyed leaves and petioles. Weevils applied to plants lightly infected with M. roridum (1 million spores/ml) gave more effective control. Net rate of biomass increment was significantly reduced for all weevil-pathogen combinations. Net biomass however still increased with treatment levels of five and eight pairs of weevils. Treatment with ten pairs of weevils prevented any increase in biomass but failed to significantly reduce original biomass. Significant reduction in plant size was observed after four weeks for all weevil-pathogen combinations.

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Item Type:	Article
Additional Information:	4 ill.; 2 tables; 14 ref. Summary (En)
AGROVOC Term:	EICHHORNIA
AGROVOC Term:	NEOCHETINA EICHHORNIAE
AGROVOC Term:	MYROTHECIUM
AGROVOC Term:	CONTROL BIOLOGICO
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:55
URI:	http://webagris.upm.edu.my/id/eprint/20100

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