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)

ALLEGRUCCI, NATALIA; VELAZQUEZ, MARIA SILVANA; RUSSO, MARÍA LETICIA; PEREZ, EMILIA; SCORSETTI, ANA CLARA

Journal of Plant Protection Research

INSTITUTE OF PLANT PROTECTION - NATIONAL RESEARCH INSTITUTE

Año: 2018 vol. 57 p. 331 - 337

Fungal entomopathogens can naturally regulate populations of various insects. The entomopathogenBeauveria bassiana (Bals.- Criv.) Vuill. is also able to endophytically colonizedifferent plants. Endophytic colonization by entomopathogens may provide a source ofindirect interactions between fungi and insects and has been associated with the ability ofthe fungus to control insect pests. The tomato leaf miner, Tuta absoluta (Meyrick) is consideredone of the most devastating pests of tomato (Solanum lycopersicum L.) and its difficultcontrol is due to its miner habit, short life cycle, and high reproductive capacity. The aimsof this study were: (i) to use three different techniques, i.e. leaf spraying, seed immersionand 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. absolutaafter inoculation. The percentage of colonization by B. bassiana was assessed 7, 14 and28 days after inoculation. All inoculation techniques employed allowed the recovery ofB. bassiana, although our results showed significant differences between techniques. Leafspraying was the most effective, with the highest percentage of colonization recorded 7 daysafter inoculation. We also evaluated (i) the effect on the mortality of T. absoluta by directcontact with conidia of B. bassiana, and (ii) the effect on tomato leaf consumption andmortality 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 orindirectly, via ingestion of inoculated tomato leaves. Direct contact showed a higher percentageof mortality and a lower median survival time (MST) than indirect contact. Significantdifferences in the mortality percentages of T. absoluta after exposure with B. bassianawere found among the treatments and the control. Our results suggest that the endophyticinoculation 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.