|Kariuki, Charles - KENYA AGRIC RES INST|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 27, 1999
Publication Date: N/A
Interpretive Summary: The diamondback moth is an important cosmopolitan pest of cole crops (i.e., cabbage, kale) in numerous countries, including the U.S., where it is also one of three major pests of vegetable crops. There is no adequate method of controlling the diamondback moth because it has developed resistance to both chemical insecticides as well a insect toxin from a bacterium. The present report describes the use of a recently isolated insect virus for the biological control of the diamondback moth. It has proven to be approximately 1000- to 2,000-fold more infectious to the diamondback moth than two other commonly used broad-spectrum baculoviruses. This new agent has application to the agricultural industry as a potential commercial product for the control of the diamondback moth, as well as for several other major pests.
Technical Abstract: This study describes a new baculovirus isolate recovered from infected larvae of the diamondback moth (DBM) Plutella xylostella (L.) and identified as a multiple nucleopolyhedrovirus (MNPV). The isolate designated as PxMNPVCL3 was found to be pathogenic to P. xylostella, Heliothis virescens, Trichoplusia ni, H. subflexa, Helicoverpa zea, Spodoptera exigua and S. frugiperda, in decreasing order of susceptibility The LC50 for DBM, the most susceptible, was 6 occlusion bodies (OB)/cm**2, whereas the most resistant species, namely S. frugiperda, was 577 OB/cm**2. PxMNPVCL3 was more pathogenic to DBM by 3 to 4 orders of magnitude as compared with two broad-spectrum baculoviruses, namely Autographa californica (alfalfa looper) MNPV and Anagrapha falcifera (celery looper) MNPV. The three baculoviruses were compared to each other and characterized by restriction endonuclease (REN) analysis, hybridization and dneutralization tests. Fragmentation profiles generated by REN showed that the three baculoviruses shared some fragments in common. Hybridization studies employing digoxigenin-labeled PxMNPVCL3 DNA as a probe revealed the close but distinct relationship of these three viruses. Neutralization tests confirmed the hybridization studies; namely that the three viruses are related but distinct.