A new Montana State University study provides some respite to sweetpotato cultivators. The researchers have found a non-toxic means to get rid of weevils, Cylas formicarius (Fabricius), considered to be the most dangerous pests, damaging sweet potatoes in the fields and in storage.
Until now farmers have not been successful in controlling the pests because the larval period occurs within vines or tubers and the adults are nocturnal. Even though the recently introduced mass trapping method (using synthetic pheromones) has restricted the weevil males' populations in several countries; it has been found ineffective in restraining the amount of damage to the tubes.
The recent study has found the usage of color traps to be very efficient in reducing the populations of the sweetpotato weevils than the existing means. The researchers found green traps to be successful in destroying the weevils in indoor conditions, while red traps seemed to work in outdoor field conditions.
For the study, MSU researchers and Nirupa Gadi of the University of Guam placed different colored traps for the insects. Among them, the color green was popular indoors, attracting nearly double the number of weevils than the current standard traps.
"Sweetpotato weevils responded to pheromone baited traps of different colors differently in the field and indoors," Dr. Gadi V.P. Reddy said in a press release. "In the field, sweetpotato weevils preferred red, and particularly light red, over the other colors, but indoors, green traps were favored. We have no explanation for the difference. Further studies focusing on why insect behavior changes from outdoors to indoors will be required to find out."
Reddy said that further studies are required to determine the reasons for the weevils' color preference.
"If we use proper color...we can see a 40% increase in catching the weevil," Reddy told Nature World News in an email.
The findings have been published in the journal Annals of the Entomological Society of America.
According to the University of Florida, the pests were first observed in Louisiana in 1875, and then eventually in Florida (1878) and Texas (1890). Sweetpotato weevils are now predominantly found throughout the coastal plain of the Southeast (from North Carolina to Texas), Hawaii, Puerto Rico, and in tropical regions (worldwide).
