|Shapiro Ilan, David|
Submitted to: Pecan Grower
Publication Type: Trade Journal
Publication Acceptance Date: 3/9/2004
Publication Date: 6/15/2004
Citation: Shapiro Ilan, D.I., Stuart, R., Mccoy, C.W. 2004. Picking the best nematode for controlling the pecan weevil. Pecan Grower. 15(4):11-15. Interpretive Summary: Insect-killing nematodes are small round worms that cause disease and kill insect pests but don't harm people or the environment. The nematodes are promising natural control agents for suppression of the pecan weevil, which is a key insect pest of pecans. In order to choose the best nematode to use against the pecan weevil, we conducted experiments on eight different stains to determine which had the greatest killing power, reproductive capacity and ability to withstand environmental conditions such as heat or desiccation. Information obtained from these experiments will be used in a genetic improvement program to develop nematodes with superior pecan weevil control abilities. The highest performing of these strains will then be tested under field conditions to verify which is the best.
Technical Abstract: Entomopathogenic nematodes kill insects but do not harm plants, or people, and are safe to the environment. Field trials indicate that these nematodes can suppress pecan weevil adults, but the level of control that the nematodes provide will probably have to be improved. The ability of entomopathogenic nematodes to successfully control a pest depends on a variety of beneficial characteristics such as virulence (innate ability to kill), tolerance to hot or dry conditions, and reproductive capacity. Different nematode strains possess a different array of beneficial traits. The objective of this study was to compare beneficial traits among strains of the nematode, Steinernema carpocapsae, so that we can identify or develop a superior nematode candidate for suppression of the pecan weevil. Virulence, environmental tolerance to heat and desiccation, and reproductive capacity were compared among eight strains. Significant differences were detected among nematode strains for each trait. No single S. carpocapsae strain was superior for all beneficial traits measured. Overall, a strain called Agriotos was ranked the best followed by the Sal and All strains; an Italian strain had the highest virulence. This information will now be used in a strain improvement program (using genetic selection and inbreeding) to develop improved nematode strains.