Western Colorado Insects

Native Plant Seed Production

Introduction
Scientific Name: Lupinus sericeus

Common Name: Silky lupine

Plant Abbreviation: L. sericeus = LUSE , L. argenteus = LUAR

Description: Lupines are widely distributed throughout the US and several species are grown for reclamation, revegetation and horticultural purposes. There are many horticultural varieties of lupine available. Several pests attack lupine seed production. There are seed feeders, pod feeders, foliage feeders, and sucking insects. Many are Lupinus specific, some are legume specific and some such as lygus are generalist feeders.

Lima Bean Pod Borer

Scientific Name: Lepidoptera: Pyralidae: Etiella zinckenella

The lima bean pod borer is a primarily tropical species whose larva feeds within seed pods of many legumes, including lupine. At this point it is known in lupine from a seed increase block of Lupinus sericeus at the Western Colorado Research Center at Rogers Mesa, near Hotchkiss CO. It was also present in a wildland lupine collection from Gunnison County CO. The initial infestation at Hotchkiss was noted the same year that transplants were planted. Moth numbers increased during the second season plants were grown. We estimated there was a 10% seed loss due to Etiella in the second year of production.

Adult Pod borer moths are almost 1 cm in length with the wings folded as in the photograph. There is an apparent "snout" that is actually formed by long palpi, part of the mouthparts. The moths are dark gray in color with a reddish band about 1/3 of the way down the wings. Moth activity is nocturnal, so they will be rarely seen. Moth flight will coincide with the appearance of fully expanded, but not yet filled seed pods. Pod borer moths
Egg Eggs have not been observed yet, but larvae apparently chew a hole in the developing pod to reach the seeds. The adult moth has no mouthparts or ovipositor capable of piercing the pod. We can infer from this that eggs are laid externally on the pods as seeds are growing. Moth entry hole
Larvae

Larvae feed inside infested pods which can be recognized by the presence of an entry hole. Larvae will wriggle around when disturbed.

Most larvae are pale green in color, but reddish and black color forms also can be found. Larvae are 2.5 cm long when fully grown.

This picture was taken by Frank Peairs in dry beans in Honduras.

Pima Damage

Pupae Larvae leave the plant to pupate, probably in the soil. Pupae are naked, brown, and about 1 long. Pima pupae

Management
Management decisions for pod borers may be difficult since there are no established monitoring methods or thresholds. Growers are encouraged to observe whether pod borer damage is present in increase blocks whenever seed is present. Once it is determined that Etiella is established in a block, growers much take a decision as to how much damage can be tolerated.

Cultural controls will focus on limiting the number of Etiella moths that can lay eggs. Locate Lupine fields as far as possible from native or horticultural lupines. If pod borer larvae are present in a seed increase, rogue and destroy infested seed pods before larvae exit and pupate. Nothing is know about natural enemies of this insect under our conditions.

Any chemical control must be preventative in nature. Sprays must target either adult moths before they lay eggs or larvae as the hatch from eggs, but before they chew an entry hole in the pod. Once they enter a seed pod, the damage has occurred and control will be impossible. Since Lupines are indeterminate bloomers, sprays must be chosen to minimize impacts on pollinators. If broad spectrum residual insecticides such as pyrethroids are used, they must be applied at night so they dry completely before pollinators become active. Pollinator friendly insect growth regulators may be an effective option. Management with biologicals such as Bacillus thuringiensis kurstaki might be possible but will require repeated applications because of the short residual of those materials.

Photo Gallery
Many species of lupine are grown for seed. Most have whitish to blue flowers. This species was photographed in Gunnison County CO. This picture shows the flowers and seed pods on a plant in a native setting. Lupine

Links
http://www.avrdc.org/LC/soybean/limaborer.html

This page was updated on April 26, 2014