Integrated Biological Control of Eichhornia crassipes (Mart.) Solms Using Phytopathogenic Fungi and Water Hyacinth Mites: Orthogalumna terebrantis

Abstract

Eichhornia crassipes (Mart.) Solms, commonly known as water hyacinth, is considered one of the most noxious aquatic invasive plants, which is also listed under the “hundred of the world’s worst invasive alien species” list. The present study was based on the isolation and identification of phytopathogenic fungi as potential biological control agents for water hyacinth and to determine integration along with water hyacinth mites (Orthogalumna terebrantis) as an effective biological control method. Six fungal species were identified as effective biological control agents from 28 total fungal isolates. Potential fungal species were identified as Trichoderma sp., Penicillium sp., Exserohilum sp., Alternaria sp., Fusarium sp., and Aspergillus sp. using microscopic features. The greatest level of pathogenicity (73.8±7.3%) was observed in Alternaria sp., with descending levels of pathogenicity noted in Fusarium sp. (57.5±4.8%), Exserohilum sp. (56.4±2.7%), Aspergillus sp. (45.6±1.7%), Penicillium sp. (36.5±3.7%), and Trichoderma sp. (33.4±1.4%) after 28 days. Damage due to water hyacinth mites was recorded as 11.6±0.7% of the total leaf area after four weeks of introduction of 50 mites per plant. The results obtained from the integrated effect study revealed that the pathogenicity of identified phytopathogenic fungal species significantly increased (p<0.05) when introduced with water hyacinth mites. Fusarium sp. has increased its pathogenicity from 73.8±7.3% to 92.8 ±7.6% of the total leaf. The pathogenicity of the remaining two fungal species, namely Alternaria sp. and Exserohilum sp., exhibited significant impact, ranging from 57.5±4.8% to 78.5±5.2% and from 56.4±2.7% to 75.3±4.8% of the entire leaf area, respectively. The study findings indicated that combining water hyacinth mites with phytopathogenic fungi is more effective than employing individual pathogenic fungal agents in isolation. Thus, the present study provides baseline data for future research to use fungi as a potential biological control method for water hyacinth.

KEYWORDS: Water hyacinth, Water hyacinth mite, Fusarium sp., Alternaria sp., Exserohilum sp., Biological control