Abstract
The fungus Metarhizium anisopliae var. acridum, strain CG 423, was tested under field conditions against the gregarious grasshopper Rhammatocerus schistocercoides (Rehn) (Orthoptera: Acrididae). Conidia formulated in a racemic mixture of soybean oil and kerosene were sprayed under field conditions using an ultralow-volume hand-held atomizer Ulva Plus adjusted to deliver 2.9 L/ha. Bands composed of 2nd instar nymphs were treated with either 5.0x10(12) or 1.0x10(13) viable conidia/ha. The number of insects in each band was estimated at day one following spraying and by the end of the field trial (15 to 16 days post-treatment). Reductions in population size reached, in average, 65.8% and 80.4% for bands treated with the higher and lower dosage, respectively. For both dosages, total mortality rates of insects collected at two days post-application, and kept in cages for 14 days under lab conditions, showed no significant differences as compared to that obtained with insects collected immediately after spraying. Healthy insects were fed to native grasses sprayed on the field with 1.0x10(13) viable conidia/ha. Mortality levels of the nymphs fed on grasses collected two and four days post-application were not affected when compared to nymphs fed on grasses collected immediately following application.
Highlights
Biopesticides represent approximately 1.3% of the phytosanitary products used in the world, those directed to insect control have 4.5% of the market share for insecticides (Menn & Hall, 1999)
The private company Mycotech (Butte, Montana, USA) has developed a diphasic fermentation system that allows an average yield of 2.6x1010 conidia of Beauveria bassiana per gram on a proprietary substrate (Johnson et al, 1992)
The results demonstrate that the invasive capability of conidia exposed to environmental constraints for at least two days is not being severely affected
Summary
Biopesticides represent approximately 1.3% of the phytosanitary products used in the world, those directed to insect control have 4.5% of the market share for insecticides (Menn & Hall, 1999). In Brazil, production methods of entomopathogenic fungi were developed in the 70 ́s (Aquino et al, 1977), and are based on rice as the substrate. The yields are relatively low and, for fungi such as Metarhizium anisopliae var. Anisopliae, vary from 2.5 to 6.0x109 conidia per gram under laboratory conditions (Quintela, 1994; Magalhães & Frazão, 1996). The private company Mycotech (Butte, Montana, USA) has developed a diphasic fermentation system that allows an average yield of 2.6x1010 conidia of Beauveria bassiana per gram on a proprietary substrate (Johnson et al, 1992). The balance between economically feasible rates and satisfactory control levels is delicate and, in some situations, responsible for failure cases of biological control programs based on entomopathogenic fungi. Studies carried out at field conditions aiming the establishment of appropriate dosages are critical in biological control programs involving biopesticides
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
