Field Guide of Discovery-based Exercises for - Aseanipm ...

Section 4 • Integrated Insect and Rodent Pests Management
Exercise No. 4.11 149
FARM-LEVEL PRODUCTION AND USE OF NUCLEAR
POLYHEDROSIS VIRUS (NPV) AGAINST COMMON
CUTWORM OF ORGANICALLY-GROWN VEGETABLES
BaCKGroUND aND raTIoNalE
One of the insect pests that can readily reduce yield of
many organically-grown vegetable crops is common
cutworm, Spodoptera litura Fabricius. Common cutworm
was previously considered a minor or an occasional insect
pest. However, it is beginning to be a perennial problem
in many crops. In addition, it feeds on a wide variety of
plants, having been reported on at least 120 crop species.
Aside from tomato, other crops like eggplant, potato, sweet
and hot peppers, okra, cabbage, pechay, cauliflower, radish,
gabi, peanut, and other legumes are among its primary hosts,
which are widely cultivated in the Philippines and other Southeast Asian countries. In most crops,
damage results from extensive feeding of larvae on leaves causing stripping of vegetable plants.
Many natural enemies of cutworm have been reported. About 10 parasitoids belonging to three
genera, namely, Trichogramma, Chelonus, and Telonomus parasitize the eggs. On the other
hand, 58 species of parasitoids belonging to different families of Hymenoptera like Braconidae,
Ichneumonidae, Eulophidae, Chalcidae, Scelionidae, Encyrtidae; one family of Diptera (Tachinidae)
had been reported as larval-pupal parasitoid. Several groups of microorganisms also cause mortality
of common cutworms. These are protozoans, fungi, nematodes, and viruses, which include nuclear
polyhedrosis viruses or NPVs.
NPVs are highly host specific obligate parasites of insects that multiply in all internal organs and
tissues, killing host insects. The route of infection is through ingestion. The host larvae acquire
NPV virus when they feed on contaminated leaves and other plant parts. NPVs, however, do not
cause diseases in mammals, birds, fishes, and non-target insects. The virus is spread by wind,
splashes of rain, and by contaminated insects or fecal materials of insects that feed on juices of
infected cadavers.
149 Adapted from Navasero, M.V. and M.M. Navasero. 2005. Farm-level production and utilization of nuclear polyhedrosis virus of the common cutworm,
Spodoptera litura Fabricius (Noctuidae, Lepidoptera) for tomato production. Paper presented during a Workshop on Integrated Production and Pest
Management in Processing Tomato: Issues and Prospects held in Laoag City, Ilocos Norte, Philippines on July 2005. 10p.
215
when is this exercise most
appropriate?
ɶ In FFS, TOT, and VST
sessions, when there is
a relatively moderate to
serious common cutworm
infestation on organicallygrown
vegetables in
learning and adjoining
fields; and
ɶ When farmers want to
learn the appropriate
time to mass-produce
NPV to control common
cutworms of organicallygrown
vegetables.