2014 statewide trapping system crucial for spotted wing Drosophila and brown marmorated stink bug

New statewide project addresses monitoring and reporting the first catch of two new invasive pests, spotted wing Drosophila and brown marmorated stink bug, in Michigan fruit systems.

Spotted wing Drosophila (SWD) and brown marmorated stink bug (BMSB) are two invasive insect pests that pose threats to Michigan’s fruit production. Both pests have been detected in the state by the Michigan State University Extension field and campus fruit team. SWD was first found in blueberries in fall 2010, and since, populations have increased dramatically in many fruit crops across the state: cherries, blueberries, strawberries, black berries and red raspberries. In most fields and orchards, this insect is now considered a key pest that requires a well-timed control program to protect fruits from infestation.

Brown marmorated stink bug, on the other hand, was first found in the state in very small numbers in 2011 and 2012, but late into 2013 BMSB numbers increased in isolated hot spots and adults were detected in residential areas, primarily in the southern half of the Lower Peninsula. Up until this point, January 2014, no controls have targeted BMSB, but the potential for the BMSB population to increase is inevitable, and Michigan growers will likely have to implement new management programs to control this pest within the next one to three years.

Why monitor for SWD?

SWD, a native pest of Southeast Asia, was first detected in the United States in Hawaii in the 1980s. This insect thrived in the contiguous states where it was found in California in 2008 and moved up the western coast of the United States and into Florida in 2009. In 2010, SWD was detected in small numbers in Utah, the Carolinas, Wisconsin and Michigan.

SWD is similar to other fruit and vinegar flies in the genus Drosophila. However, other Drosophila feed exclusively upon and lay eggs in ripe or overripe fruit, and although SWD prefers to lay eggs in ripening fruit, it can attack less ripe fruit as females have two rows of serrations on the ovipositor that allow them to “saw” into unripe fruit to lay eggs. Similar to other Drosophila, SWD can produce many generations in a relatively short amount of time, and the optimal development of SWD is between 65-70 degrees Fahrenheit, which are normal conditions for a Michigan growing season. Under these conditions, the generation time can be as short as 12 days.

Because SWD reproduces so quickly under optimum conditions, the first catch information is vital to activate pest management programs to prevent rapid population increases and potential infestations in a region. Our statewide monitoring will be essential to the Michigan fruit industry, particularly in establishing the first SWD catch in a region as this information guides future SWD management programs and individual on-farm monitoring efforts.

Why monitor for BMSB?

BMSB was introduced from Asia 20 years ago and has a host range of over 300 known plants, including many fruits commercially grown in Michigan. Thus, BMSB has the potential to dramatically reduce the quality of peaches and cherries produced in Michigan, but BMSB is also a primary concern for apple producers.

BMSM has been monitored in Michigan for the past few years, but those efforts were not part of an extensive statewide trapping program. In other states, BMSB populations have reached high enough numbers to cause substantial damage in tree fruits, and in New York, apple growers were unaware of any BMSB activity in orchards in 2011, yet experienced severe crop losses (20-30 percent) in the 2012-growing season. This scenario stresses the importance of establishing a coordinated statewide monitoring and reporting system for BMSB to mitigate losses in Michigan tree fruit crops.

Knowledge gained will inform pest management

Because first detection and general knowledge and understanding of these two new invasives are vital to subsequent, informed control decision-making by Michigan fruit growers, our 2014 efforts will provide Michigan growers with up-to-date information on SWD and BMSB status in apples, cherries, raspberries, strawberries and blackberries through a coordinated intensive statewide trapping system for the presence of SWD and BMSB. Thanks to Project GREEEN funding, MSU Extension looks forward to helping Michigan’s fruit industry face the challenges of new invasive insect pests this coming season.

Dr. Rothwell’s work is funded in part by MSU’s AgBioResearch.

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