Endophytic colonisation of tomato by the entomopathogenic fungus Beauveria bassiana: the use of different inoculation techniques and their effects on the tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae)

Abstract

Fungal entomopathogens can naturally regulate populations of various insects. The entomopathogen Beauveria bassiana (Bals.-Criv.) Vuill. is also able to endophytically colonize different plants. Endophytic colonization by entomopathogens may provide a source of indirect interactions between fungi and insects and has been associated with the ability of the fungus to control insect pests. The tomato leaf miner, Tuta absoluta (Meyrick) is considered one of the most devastating pests of tomato (Solanum lycopersicum L.) and its difficult control is due to its miner habit, short life cycle, and high reproductive capacity. The aims of this study were: (i) to use three different techniques, i.e. leaf spraying, seed immersion and root dipping, for the endophytic inoculation of B. bassiana in tomato plants; and (ii) to assess the effect of B. bassiana on tomato leaf consumption and mortality of T. absoluta after inoculation. The percentage of colonization by B. bassiana was assessed 7, 14 and 28 days after inoculation. All inoculation techniques employed allowed the recovery of B. bassiana, although our results showed significant differences between techniques. Leaf spraying was the most effective, with the highest percentage of colonization recorded 7 days after inoculation. We also evaluated (i) the effect on the mortality of T. absoluta by direct contact with conidia of B. bassiana, and (ii) the effect on tomato leaf consumption and mortality by indirect contact through ingestion of inoculated plant tissues with B. bassiana. Mortality bioassays showed that B. bassiana infected T. absoluta, either by direct contact or indirectly, via ingestion of inoculated tomato leaves. Direct contact showed a higher percentage of mortality and a lower median survival time (MST) than indirect contact. Significant differences in the mortality percentages of T. absoluta after exposure with B. bassiana were found among the treatments and the control. Our results suggest that the endophytic inoculation of B. bassiana in tomato crops provides the basis for further investigation, which should focus on the virulence of the endophytic B. bassiana against T. absoluta.

Endophytic colonization of tomato plants by the entomopathogenic fungus Beauveria bassiana for controlling the South American tomato pinworm, Tuta absoluta

“…No endophytic colonization of plants was detected here by soaking seeds in fungal suspensions. Seed treatment with B. bassiana conidial suspensions was also found to be of low efficiency in the endophytic colonization of tobacco, corn, wheat, soybeans (Russo et al 2015) and tomato (Allegrucci et al 2017). Alternatively, other workers have used tomato seed inoculation methods to successfully colonize plants (Ownley et al 2008;Powell et al 2009;Sánchez-Rodríguez et al 2015;Shrivastava et al 2015).…”

“…Inoculation methods include leaf spraying, injection through the stem, soil irrigation and seed treatments (Bing and Lewis 1992;Quesada-Moraga et al 2006). Tomato plants have been artificially colonized by EPF (Klieber and Reineke 2016;Allegrucci et al 2017) with low persistence of the fungi as endophytes and efficiency when considering T. absoluta control.…”

Endophytic colonization by Beauveria bassiana increases the resistance of tomatoes against Bemisia tabaci

“…The primed plants show quicker and/or stronger induction of various cellular defense responses than untreated plants, after exposure to pathogens, herbivorous insects, or abiotic stress (Hokkanen and Menzler-Hokkanen 2017;Kuc 1987;Martinez-Medina et al 2016;Slaughter et al 2012;Ye et al 2013). Many well-known defense systems have evolved to combat insect attack (Akello and Sikora 2012;Allegrucci et al 2018). This process mainly involves antifeedant or toxic compounds that inhibit insect performance (McCormick et al 2016), even emission of volatiles that attract natural enemies (Shivaramu et al 2017).…”

Endophytic fungi for sustainable agriculture

“…most of the commercially produced entomopathogenic fungi can be endophytic for part of their life cycle and include the species of Beauveria, Metarrhizium, Lecanicillium and Isaria (Lugtenberg et al 2016); they are effective against several root-feeding insects belonging to different orders, such as the root mealy bug, Cataenococcus ensete, the sugar beet root maggot, Tetanops myopaeformis, the diabroticine rootworms, and the white grubs Melolontha and Popillia japonica (Lugtenberg et al 2016). Beauveria bassiana is an entomopathogenic fungus with worldwide distribution, which can live as a plant endophyte; colonization of plant tissues by B. bassiana has proved to provide protection against insect damage and inhibition of insect establishment and development (Vega et al 2008;Allegrucci et al 2017). Fungal endophytes B. bassiana and Clonostachys rosea collected of coffee plants from Hawaii, Colombia, Mexico and Puerto Rico appeared to be pathogenic to the coffee berry borer (Hypothenemus hampei) that is the most devastating pest of coffee throughout the world (Vega et al 2010).…”

“…The endophytic growth of B. bassiana in corn plant tissues by cause higher mortality of larvae of the European corn borer (Ostrinia nublialis Hbn) (Vidal 2015). B. bassiana was able to infect T. absoluta (leaf miner pest of tomato leaves) either by direct contact with conidia or indirectly by ingestion of tomato leaves colonized endophytically result in mortality up to 50% or higher, (Allegrucci et al 2017).…”