ENTOMOPATHOGENIC FUNGI – Isaria fumosorosea

ENTOMOPATHOGENIC FUNGI – Isaria fumosorosea

General Characteristics of Isaria fumosorosea

• Isaria fumosorosea and Isaria farinose are formerly known as Paecilomyces fumosoroseus and Paecilomyces farinosus, are important entomopathogenic fungi with a worldwide distribution and multiple host insects.
• Isaria fumosorosea have multiple hosts, do not show harmful effects linked to the use of chemical pesticides, and are considered to be environmentally friendly.
• Besides their application as pest biocontrol agents, both Isaria fumosorosea and Isaria farinose have potential uses in the biotransformation of flavonoids glycosides, steroids, etc.

Habitat of Isaria fumosorosea 

• Isaria fumosorosea is commonly found in the soil but has been reported on plants, in water, and less commonly in air.

Target Insects of Isaria fumosorosea 

• Isaria fumosorosea is a species complex and mainly infects Hemipteran and Lepidopteron insects, such as Aphids, Leafhoppers, Whiteflies, and the Asian citrus psyllid, etc.
• Some of the more commonly known susceptible insects include Weevils, Ground beetles, Plant Beetles, Wasps, Termites, Thrips, and a wide variety of Butterflies and Moths.
• Because of its wide arthropod host range, Isaria fumosorosea has received significant attention as a biological control agent for several economically important insect pests of agricultural crops. 

Mode of action of Isaria fumosorosea 

• Like most entomopathogenic fungi, Isaria fumosorosea infects its host by breaching the cuticle.
• Various metabolites allow the pathogen to physically penetrate the host and inhibit its regulatory system.
• For Isaria fumosorosea, these include Proteases, Chitinases, Chitosanase and Lipase. These enzymes allow the fungus to breach the insect cuticle and disperse through the Hemocoel. 
• Isaria fumosorosea and other species within the genus also produce Beauvericin, a compound that appears to paralyze host cells.
• Susceptible insects exposed to blastospores and conidia of Isaria fumosorosea show declined growth and high levels of mortality.

Figure – 1: Insects affected with Isaria fumosorosea 

Microscopic characteristics of Isaria fumosorosea

• Isaria fumosorosea shows erect conidiophores bearing several compact whorls of phialides, with a strongly inflated base; cylindrical to fusiform conidia, 3 – 4 × 1 - 2 µm.

Cultural characteristics of Isaria fumosorosea

• In Potato Dextrose Agar (PDA) medium, Isaria fumosorosea colonies reached a 4 cm diameter in 14 days, at 25 °C, appearing raised, floccose, and pale pink.

Figure – 2: Cultural characteristics of Isaria fumosorosea

Uses of Isaria fumosorosea

• Isaria fumosorosea has been used to control insect pests of plants grown for the production of Flowers, Ornamentals growing in greenhouses and nurseries, Vegetable crops, Cotton, Maize and Rice.
• It has also been found to reduce the development and spread of powdery mildew, Sphaerotheca fuliginea on Cucumbers.

Advantages of Isaria fumosorosea

• Non-toxic to beneficial insects, humans and animals.
• Used for Integrated Pest Management (IPM) by many organic farmers.
• Reduce the use of chemical insecticide sprays, which are extremely toxic and expensive.