Submitted to: American Society of Sugarbeet Technologists
Publication Type: Proceedings
Publication Acceptance Date: March 9, 1995
Publication Date: N/A
Interpretive Summary: Biological control agents can be an important means of pest control and can play a significant part in integrated pest management systems. Their use requires specific environmental conditions and cultural practices to optimize their activity. This is not unlike the requirements for effective chemical pest control. It is important to realize, however, that the results of chemical control are frequently more immediate than biological control agents. The sugarbeet research scientists at the ARS laboratory in Fargo are now studying the following five biological control approaches: (1) development and use of insect specific parasitic fungi; (2) development and use of insect specific parasitic nematodes; (3) development of genetically resistant breeding lines; (4) the use of Bacillus thuringiensis (Bt) as a toxic protein producer; and (5) natural root and insect associated bacteria.
Technical Abstract: Fungi are unique among insect pathogens because they infect by penetrating the external cuticle instead of the gut. We have identified pathogenic fungi which may become part of the arsenal for biological control of the sugarbeet root maggot. We are investigating the entomopathogenic fungi Beauvaria bassiana and Metarhizium anisopliae for their pathogenicity and virulence to the root maggot. We have tested both of these fungi in the laboratory for their ability to infect and kill developmental stages of the larvae and the adult fly. We have determined that fungal infection is not limited to a single developmental stage. We have found infection in eggs, first, second, and third instars and in adults. Infection and mortalities for the early larval stage of the insect (first instar) is presented in Table 1. Mortality for B. Bassiana infected larvae in the early stage of development ranged from 15% at 7 days to 100% at 13 days. For M. Anisopliae fungi, mortality was 67% and 100% at 7 and 13 days, respectively.