title: Transient endophytic colonizations of plants improve the outcome of foliar applications of mycoinsecticides against chewing insects.
abstract: The current work reports how spray application of entomopathogenic fungi on alfalfa, tomato and melon plants may cause an additional Spodoptera littoralis larvae mortality due to a temporal colonization of the leaves and subsequent ingestion of those leaves by the larvae. Most entomopathogenic fungi (EF) (Ascomycota: Hypocreales) endophytes seem to colonize their host plants in a non-systemic pattern, in which case at least a transient endophytic establishment of the fungus should be expected in treated areas after spray application. In this work, all strains were able to endophytically colonize roots, stems and leaves during the first 96h after inoculation. Whilst the treatment of S. littoralis larvae with a 10(8)ml(-1) conidial suspension resulted in moderate to high mortality rates for the Metarhizium brunneum EAMb 09/01-Su (41.7-50.0%) and Beauveria bassiana EABb 01/33-Su (66.7-76.6%) strains, respectively, an additive effect was detected when these larvae were also fed endophytically colonized alfalfa, tomato, and melon leaves, with mortality rates varying from 25.0% to 46.7% as a function of the host plant and total mortality rates in the combined treatment of 75-80% and 33-60% for B. bassiana and M. brunneum, respectively. Fungal outgrowth was not detected in any of the dead larvae feeding on colonized leaves, whereas traces of destruxin A were detected in 11% of the insects fed tomato discs endophytically colonized by M. brunneum. The combined effects of the fungal spray with the mortality caused by the feeding of insects on transient EF-colonized leaves have to be considered to estimate the real acute impact of field sprays with entomopathogenic fungi on chewing insects.
authors.affiliation: Department of Agricultural and Forestry Sciences, ETSIAM, University of Cordoba, Campus de Rabanales, Building C4 "Celestino Mutis", Cordoba 14071, Spain; Faculty of Agrarian Sciences of the National University of Asunción, Paraguay.
authors.forename: G
authors.initials: G
authors.lastname: Resquín-Romero
authors.affiliation: Department of Agricultural and Forestry Sciences, ETSIAM, University of Cordoba, Campus de Rabanales, Building C4 "Celestino Mutis", Cordoba 14071, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Garrido-Jurado
authors.affiliation: Department of Agricultural and Forestry Sciences, ETSIAM, University of Cordoba, Campus de Rabanales, Building C4 "Celestino Mutis", Cordoba 14071, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Delso
authors.affiliation: Department of Agricultural and Forestry Sciences, ETSIAM, University of Cordoba, Campus de Rabanales, Building C4 "Celestino Mutis", Cordoba 14071, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Ríos-Moreno
authors.affiliation: Department of Agricultural and Forestry Sciences, ETSIAM, University of Cordoba, Campus de Rabanales, Building C4 "Celestino Mutis", Cordoba 14071, Spain. Electronic address: equesada@uco.es.
authors.forename: E
authors.initials: E
authors.lastname: Quesada-Moraga
mesh_terms: D000818:Animals; D052982:Beauveria; D007306:Insecticides / Q000008:administration & dosage*; D007814:Larva / Q000382:microbiology; D052981:Metarhizium; D010572:Pest Control, Biological / Q000379:methods*; D010935:Plant Diseases / Q000382:microbiology*; D010944:Plants / Q000382:microbiology; D018411:Spodoptera / Q000382:microbiology*
chemical_list: D007306:Insecticides
keywords: Beauveria bassiana; Biological control; Endophyte; Metarhizium brunneum; Systemic protection