Monitoring of the field application of Metarhizium anisopliae in Brazil revealed high molecular diversity of Metarhizium spp in insects, soil and sugarcane roots

Abstract

The use of Metarhizium against sugarcane spittlebugs in Brazil is one of the most successful and long lasting biological control programs using entomopathogenic fungus in the world. However, studies to monitor the fate of this fungus on the sugarcane agroecosystem are rare, especially with respect to its persistence, efficacy in pest control and impact on the local populations of Metarhizium. The present study aimed at documenting the efficacy and persistence of M. anisopliae strain ESALQ1604 in a sugarcane field by using microsatellite molecular markers. The species diversity of Metarhizium was characterized in insects, soil and sugarcane roots in a sprayed and an unsprayed plot. Although the infection rates were not very high (≤ 50%), the applied strain was recovered from spittlebugs after 7, 30 and 60 days’ post-application, but accounted for only 50%, 50% and 70.5% of all insects killed by M. anisopliae, respectively. All haplotypes from spittlebug were associated with a single subclade of M. anisopliae. The highest haplotype diversity was found in soil (h = 0.989) and in the smallest in spittlebug (h = 0.779). Metarhizium robertsii, M. anisopliae, M. brunneum; one taxonomically unassigned lineage was found in soil and only M. brunneum and M. anisopliae were isolated from roots. This study revealed the great diversity of Metarhizium spp. in the sugarcane agroecosystem and the importance of the local population of M. anisopliae on spittlebugs management.

Revisiting Metarhizium and the description of new species from Thailand

“…Only few records were made from Africa, South and Central America ( Samson, 1974 , Montalva et al., 2016 , Lopes et al., 2018 , Gutierrez et al., 2019 ). While most of the species discovered in Metarhizium are considered entomopathogenic, studies of their plant-growth promoting and endophytic, rhizosphere or soil-dwelling properties have been increasing ( Hu and St Leger, 2002 , Chad et al., 2014 , Iwanicki et al., 2019 ). As they continue to promote plant health by increasing nutrient absorption through the roots and killing insect pests ( Sasan and Bidochka, 2012 , Liao et al., 2014 , Liao et al., 2017 ) and being used for biological control, reports have also showed Metarhizium implicated in human infections ( Nourrisson et al.…”

Several Metarhizium Species Produce Ergot Alkaloids in a Condition-Specific Manner

“…In fact, formulations of several Metarhizium species are used as biocontrol agents to control insect pests (22). Examples include biocontrol of spittle bug on sugar cane in Brazil by M. anisopliae (23), biocontrol of locusts by formulations of M. acridum (e.g., Green Muscle and Green Guard) in Africa and Australia (24,25), as well as controlled trials of malaria-vectoring mosquitoes in Burkina Faso by genetically modified M. pingshaense (26). Significant previous research on Metarhizium species indicate that hydrolytic enzymes (19,(27)(28)(29) and a class of toxins called destruxins (30) are both important in pathogenesis of insect hosts.…”

Natural Occurrence of Entomopathogenic Fungi as Endophytes of Sugarcane (Saccharum officinarum) and in Soil of Sugarcane Fields

“…differed among locations. Several previous studies indicate that convectional agricultural practices such as application of synthetic pesticides decrease the natural incidence and diversity of the Hypocreales [ 14 , 16 , 17 , 51 ]. However, farm type did not significantly affect the distribution of EPF across locations.…”