Trichoderma virens Gl006 and Bacillus velezensis Bs006: a compatible interaction controlling Fusarium wilt of cape gooseberry.

The combination of Trichoderma virens Gl006 and B. velezensis Bs006 as a consortium has high potential to control Fusarium wilt (FW) of cape gooseberry (Physalis peruviana) caused by Fusarium oxysporum f. sp. physali (Foph). However, the interactions between these two microorganisms that influence the biocontrol activity as a consortium have not been studied. Here, we studied the interactions between Gl006 and Bs006 that keep their compatibility under in vitro and greenhouse conditions. Antagonism tests between Gl006 and Bs006 inoculated both individually and in consortium against Foph strain Map5 was carried out on several solid media. The effect of supernatant of each selected microorganism on growth, conidia germination, biofilm formation and antagonistic activity on its partner was also studied. Biocontrol activity by different combinations of cells and supernatants from both microorganisms against Fusarium wilt was evaluated under greenhouse conditions. In vitro antagonism of the consortium against Foph showed a differential response among culture media and showed compatibility among BCA under nutritional conditions close to those of the rhizosphere. The supernatant of Bs006 did not affect the antagonistic activity of Gl006 and vice versa. However, the supernatant of Bs006 promoted the biocontrol activity of Gl006 in a synergistic way under greenhouse, reducing the disease severity by 71%. These results prove the compatibility between T. virens Gl006 and B. velezensis Bs006 as a potential tool to control Fusarium wilt of cape gooseberry.

Disruption of pheromone communication in Tecia solanivora (Lepidoptera: Gelechiidae): flight tunnel and field studies.

The moth Tecia (Scrobipalpopsis) solanivora Povolny (Lepidoptera: Gelechiidae) is the most important pest of potato, Solanum spp., in Central America and adjacent South American countries. Insecticide treatments are not sufficiently effective; therefore, we investigated the feasibility of pheromone-mediated mating disruption for control of T. solanivora. Pheromone dispensers were formulated with 70 mg of the three sex pheromone compounds (E)-3-dodecenyl acetate, (Z)-3-dodecenyl acetate, and dodecyl acetate, in a ratio of 100:56:100, respectively. Male attraction to these compounds is optimal at a ratio of 100:1:20, thus the mating disruption dispensers contained an off-blend, which attracted only a few males. Nonetheless, one mating disruption dispenser suppressed male attraction to calling females in a flight tunnel and reduced male activation in response to female pheromone. Communication disruption is accordingly due to camouflage of the female signal and possibly due to a reduction of male responsiveness by sensory imbalance. Only a few males were observed in a 3-ha potato field treated with 84 g pheromone/ha, compared with an untreated control field. During 2 mo, male attraction to traps baited with calling females or synthetic pheromone was strongly reduced. This reduction confirms the potential of mating disruption for management of T. solanivora. The efficacy of the pheromone treatment can be further improved by earlier dispenser application, by increased dispenser load, and by treatment of larger fields to reduce immigration of mated females.