Isolation, Selection, and Efficacy of Pochonia chlamydosporia for Control of Rotylenchulus reniformis on Cotton

Abstract

The reniform nematode, Rotylenchulus reniformis, is a serious threat to cotton (Gossypium hirsutum) production in the United States, causing an annual loss of about $80 million. The objective of this study was to isolate fungi from eggs of R. reniformis and select potential biocontrol agents for R. reniformis on cotton. We focused on the fungus Pochonia chlamydosporia because it suppresses root-knot and cyst nematodes and because preliminary data indicated that it was present in Arkansas cotton fields. Soil samples were collected from six cotton fields in Jefferson County, Arkansas. A total of 117 isolates of the nematophagous fungus P. chlamydosporia were obtained. In an in vitro test, 105 of the 117 isolates parasitized fewer than 15% of R. reniformis eggs, but 12 isolates parasitized between 16 and 35% of the eggs. These 12 isolates produced from 6.8 x 10(4) to 6.9 x 10(5) chlamydospores per gram of medium in vitro, and chlamydospore production was similar on rice grain and corn grain media. In two greenhouse experiments, a single application of isolate 37 (5,000 chlamydospores per gram of soil) significantly reduced the numbers of R. reniformis on cotton roots and in soil. The three isolates (37, 26, and 14) that parasitized the most eggs in vitro were also the most effective in suppressing numbers of R. reniformis and in increasing cotton growth in the greenhouse.

Pathogenicity of Pochonia species on eggs of Meloidogyne javanica

“…All tested nematophagous fungi were inhibited when growing in nonsterilized soil, irrespective of the amount of nonsterilized soil (25-100%) which suggests that a lack of soil receptivity could be due to soil microbial activities (Monfort et al, 2006), therefore we used unsterile soil to achieve more accurate results. The chlamydospore is the preferred type of inoculum because it does not need an additional nutrient source (Wang et al, 2005). If conidia or hyphal fragments are used as inoculum, an energy base is required.…”

“…Number of infected eggs; uninfected eggs; and empty eggs were counted using a microscope at 40Â and 100Â magnifications. Percentage of egg infection calculated by dividing number of infected eggs to total eggs multiplied by 100 (Fatemy et al, 2005;Wang et al, 2005). Number of emerged juveniles in Petri dishes was calculated by using a stereo-microscope (Fatemy, 1998).…”

Anti-nemic secondary metabolites produced by Fusarium oxysporum f. sp. ciceris

“…(Heald and Robinson, 1990). Large number of study reported on the efficacy of bio-control agent like Paecilomyces lilacinus and Pochonia chlamydosporia in suppression of R. reniformis population (Munawar et al, 2011;Wang et al, 2005). There is growing interest in discovering the nematostatic compounds from the natural sources throughout the world.…”

Incorporação ao solo de substrato contendo micélio e conídios de Pochonia chlamydosporia para o manejo de Meloidogyne javanica

“…Verticillium chlamydosporium Goddard) é um parasita facultativo de ovos de nematoides e tem sido comumente estudado como agente de controle biológico do nematoide das galhas e de cistos (HIDALGO-DIAZ et al, 2000;KERRY & BOURNE, 2002;LOPES et al, 2007;DALLEMOLE-GIARETTA et al, 2012 (WANG et al, 2005;PÉREZ-RODRÍGUEZ et al, 2007;FREITAS et al, 2009). Aliada à capacidade de redução da produção de ovos dos patógenos nas raízes das plantas, a habilidade de P. chlamydosporia em produzir clamidósporos durante o cultivo massal em substrato sólido é um dos critérios usualmente utilizados para a seleção de isolados em programas de controle biológico de nematoides (KERRY & BOURNE, 2002).…”