Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), consists of genetically diverse species known to cause significant destruction in several crops around the world. Nymphs and adults of B. tabaci cause damage to plants during feeding, and they can act as a virus vector, thus causing significant yield loss to crops in the tropical and subtropical regions. Chemical pesticides are widely used to control B. tabaci due to their immediate action, but this approach has several drawbacks including food safety issues, insecticide resistance, environmental pollution, and the effect on non-target organisms. A biological control agent using entomopathogenic fungi (EPF) has therefore been developed as an alternative against the conventional use of chemical pesticides in an integrated pest management (IPM) system to effectively control B. tabaci. It is apparent from this review that species of hyphomycetes fungi are the most common EPF used to effectively control B. tabaci, with the second instar being the most susceptible stage of infection. Therefore, this review article focuses specifically on the control of B. tabaci with special emphasis on the use of EPF as biological control agents and their integration in IPM.
Entomocidal activity of ethanolic leaf extracts of four plant species namely Euphorbia balsamifera Aiton, Lawsonia inermis L., Mitracarpus hirtus (L.) DC. and Senna obtusifolia L. were evaluated in order to assess their protectant ability to stored sorghum against Sitophilus zeamais Motsch. The botanicals were applied to 20 g of sorghum grains at the rate of 25, 50 and 100 mgml-1 , while no extracts was added to the control. Percentage repellency was recorded at 24 h after exposure (HAE) while adult mortalities of the weevils were obtained at 3 days after treatment (DAT). Adult emergence and grain perforations were recorded at 49 and 84 DAT, respectively. Repellency levels of the botanicals against S. zeamais ranged from 87.05 ± 0.45 to 100.00 ± 0.00%. Also, the ethanolic extracts resulted in high adult mortalities of the weevils in the treated sorghum grains. No adult emergence was recorded in grains treated with the botanical extracts. Highest (10.00 ± 2.04%) grain perforations among the treatments were observed in 25 mgml-1 of S. obtusifolia, while 2.50 ± 1.25% was the least in the highest concentration of E. balsamifera. Findings of the study have revealed that the selected botanicals could serve as stored sorghum protectants against S. zeamais infestations.
Entomopathogenic fungi (EPF) are natural enemies which affect insect population and have long been recognized as biological control agents against many insect pests. Some isolates have also been established as endophytes, benefiting their host plants without causing any symptoms or negative effects. Here we demonstrated two entomopathogenic fungal species, Isariajavanica (Frieder. & Bally) Samson & Hywel-jone 2005 and Purpureocillium lilacinum (Thom) Luangsa-ard, Hou-braken, Hywel-Jones & Samson (2011) as endophytes in tomato plants by using the seed inoculation method and examined their effect on plant growth, B. tabaci mortality, and adult emergence. Our study indicated that tomato seeds treated with a fungal suspension of I. javanica and P. lilacinum enabled their recovery from plant tissues (root, stem and leaf) up to 60 days after inoculation (DAI). Both endophytic isolates also caused significant mortality of adult B. tabaci on seedlings inoculated with, I. javanica (51.92±4.78%), and P. lilacinum (45.32±0.20%) compared to the control treatment (19.29±2.35). Adult emergence rates were significantly high in the control treatments (57.50±2.66%) compared to I. javanica (15.00±1.47%) and P. lilacinum (28.75±4.78%) treatments. This study provides evidence that endophytic isolates of I. javanica and P. lilacinum have a biocontrol potentials for used against whiteflies and could also explored as plant growth promoters.
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