Evaluation of entomopathogenic action of Beauveria bassiana using two application methods: Trunk inoculation on kiwi trees and seed coating on cotton

The insecticidal action of the entomopathogenic fungus Beauveria bassiana (Hypocreales: Cordycipitaceae) has been documented for a wide range of pests, and in recent years, its formulated application has been tested in several crops. In this work, two different application methods of B. Bassiana PPRI 5339 Velifer^® were studied over two years. In one case, B. bassiana was applied as a coating to the cotton seed (treatment A) Gossypium hirsutum (Malvales: Malvaceae), and in the other case, it was applied via syringe inoculation to the kiwi trunk (treatment B) Actinidia deliciosa “Hayward” (Ericales: Actinidiaceae). For each case, plants without the application of B. bassiana were used as a control (treatment C). The sucking insects Aphis gossypii (Hemiptera: Aphididae) on cotton plants and Halyomorpha halys (Hemiptera: Pentatomidae) on kiwi trees were counted. In addition, the total chlorophyll contents and the leaf area were measured during the experiment. The presence of H. halys was significantly reduced in kiwi trees, and the total chlorophyll content in the leaves was increased. In the cotton plants, the population of A. gossypii was reduced, and the leaf area appeared larger. The presence of B. bassiana on treatments A and B, on the one hand, reduced the sucking pests, while on the other hand, it enhanced the total chlorophyll content and the leaf area. The results of both application methods are encouraging reasons to investigate B. bassiana and similar endophytes in other crops, given the biotic stresses and yield losses that can be caused by aphids or new exotic pests in Greece, such as H. halys.