Evaluation of Baculovirus Sprayings for the Management of Lepidopteran Pests in Broccoli, Guatemala, 1997
Humberto Carranza Bazini (Guatemala); Stephen Weller (US)
This study focused on determining the effectiveness of baculovirus sprays as control agents against Plutella xylostella and other common lepidopteran pests of broccoli. The baculovirus strain was obtained from the alfalfa measurer larva (Autographa californica) and the prodenia larva (Spodoptera sunia). Two field tests were established in the Departments of Chimaltenango and Jalapa from August to December 1997. Two treatments were included in the study, (1) plots treated with baculovirus sprays, and (2) plots treated with the standard management practice used by growers consisting of Bacillus thuringiensis (Bt) based commercial products. Adjacent plots of 400 m2 each were used. The number of larvae,pupae and egg nests of lepidopteran moths were measured, including: P. xylostella, Trichoplusiani, Leptophobia aripa, Spodoptera spp. and Estigmene acrea. Data were also recorded on gross and net yield (mt/ha), and costs. “T” tests and partial economic budget analysis were carried out. Results indicated that baculovirus sprayings effectively control larval populations of P. xylostella, T. ni and L. aripa in the foliage, as they were kept under 6 larvae/25 plants (economic threshold used for Bt’s sprays). However, at some points the insect pest density surpassed the above mentioned threshold, since the baculovirus sprayings did not reduce pests to lower than 6 larvae/25 plants.
The objective of the study was to determine the effectiveness of baculovirus sprays as control agents against Plutella xylostella and other common lepidopteran pests of broccoli. The baculovirus strain was obtained from the alfalfa measurer larva (Autographa californica) and the prodenia larva (Spodoptera sunia).
Researchers found that while baculovirus sprays are more expensive than the Bt's, it is a viable alternative for the control of lepidopteran larvae. If managed adequately baculovirus can be incorporated into an integrated pest management program in broccoli, as an important component to prevent development of Bt resistance in the main lepidopteran species that infest broccoli.