About the Southern Potato Wireworm
Reproduction and Life Cycle
The southern potato wireworm overwinters as larvae in the soil about 6 inches below the surface (sometimes deeper if dry conditions are presented), and will emerge as adults in April and immediately feed on available nectar and pollen. After about 10 days the females will start laying their eggs. The adults live a fairly long life, and can lay eggs for up to 120 days, averaging a total of about 36 eggs per female. The eggs are placed underneath the soils surface, about an inch deep. The eggs take 7 to 10 days to hatch. When the larvae hatch, they can take anywhere between 110 and 340 days to develop through their 5 to 7 instars, dependent on the temperature and environmental conditions. During the first instar the larvae are very active and will move through the soil searching for food. They are not picky, eating most plant tissue; they are also cannibalistic. The first 3 instars take the longest amount of time for development to be completed, often causing the final instars to occur during the fall months. In the winter the larvae enter the pupae; this stage of development takes about 7 to 10 days to complete. They will begin to twist and roll as they mature. This pest can go through 2 generations per year, 1 considered a short cycle, and the other that overwinters is considered the long cycle, taking an extended period of time to fully develop.
Southern Potato Wireworm Identification and Habitat
This pest is considered a click beetle in their final stage of development. These beetles are hard shelled, slightly flattened, and tapered with a brown body and tan legs. Their mouthparts are rust brown. They are about 5.5 to 7.5mm long and often have yellowish patches. The eggs surface is white and smooth; they are translucent and have a diameter of approximately 0.5mm. They are covered in a sticky substance that allows them to stick to soil and debris pieces, making them challenging to spot. Directly after hatching the larvae are also white, but as they mature will become more of a cream or yellow-gray colour. They have red-orange heads and can grow to be about 17mm in length. On the last section of the abdomen is a closed oval indentation. Their body will develop 3 pairs of legs. The pupa is a little bigger than what a fully matured beetle would be (about 9mm long), oblong and is white at the start, becoming pale yellow as it matures with black eyespots.
The southern potato wireworm is a pest well-known to the southeastern United States, originating from South America. They are known to damage the roots of sweet potato, carrots, potato tubers, and tobacco seedlings. They tend to prefer Irish potatoes. They also sometimes feed on beet roots, tomatoes, strawberries, gladiolus and melons. When they infest tobacco plants, they will tunnel into the stalks of the plant and eat from within. This can stunt and sometimes kill the plant, resulting in yield loss. This pest is more common in Coastal Plain and sandy soil, particularly when fields were not plowed after harvest during the fall. They are nocturnal, hiding just beneath the soils surface when the sun is out. They prefer humid and warm nights and are more active when these conditions are present.
Southern Potato Wireworm Management and Control Methods
To help control the southern potato wireworm, rotate crops that this pest would not be attracted to. Note that having satisfactory control is dependent on using an integrated management system that includes the use of cultural and chemical methods
To control the southern potato wireworm with insecticides, Di-Syston proved to have effective control. Thimet (phorate) in granular form was also successful. Diazinon and parathion were also effective when wireworm populations were not too significant. Be sure to carefully read the label for cautions and proper application. It is extremely important to never spray on days that are windy. After applying insecticides, it is important to irrigate sprayed area to increase the insect control. That being said, a large rainfall or irrigation soon after the application can reduce the concentration insecticides. Granular insecticides should be applied at planting. This pest has developed a tolerance to chlorinated hydrocarbon and some other insecticides that are organophsphate.
Latin / Alternative Southern Potato Wireworm Names