Brown marmorated stink bug isn’t new to Californians. First established in Los Angeles County, the bug also has a large presence in the Midtown area of Sacramento, and can be found in many urban areas throughout the state. In recent years, brown marmorated stink bug has also been damaging agricultural crops such as peach and almond in the northern San Joaquin Valley, especially Stanislaus and Merced counties.
Adult brown marmorated stink bugs feed on growing and mature nuts, injecting tissue-destroying enzymes that results in discolored and distorted nuts. Outward signs of bug feeding include sap oozing from the nut. Damage can occur from spring to fall, but spring and early summer feeding results in the most loss due to nut abortion and drop. Because high numbers of brown marmorated stink bug are common, and bugs can feed on more than one nut, losses can be severe.
Responding to a local grower call about dropped nuts, Area IPM Advisor Jhalendra Rijal discovered brown marmorated stink bug was the culprit. Rijal organized a field day to inform other growers and pest control advisers in the area about how to identify and monitor for the stink bug.
Trapping brown marmorated stink bugs is the best way to determine if they are in the orchard. Placing traps on the edges of orchards, especially orchards near overwintering structures or neighboring hosts—peach, nectarine, apple, pear, and ornamental trees such as tree-of-heaven—can inform growers and pest control advisers when brown marmorated stink bug is moving into orchards. Like other stink bugs, brown marmorated stink bug migrates into orchards from overwintering sites, and this early season movement is especially concerning since feeding at this time causes substantial crop loss due to abortion and drop of young nutlets.
Rijal’s previous work to determine the best trap for brown marmorated stink bug started with research in peach orchards, a favorite host of brown marmorated stink bug. He tested black pyramid and sticky panel traps with an aggregation pheromone. He found that the sticky panel trap is a more efficient and practical way to monitor brown marmorated stink bug activity in tree crop orchards in California. Rijal also promotes looking in the orchard for egg masses, stink bugs, and damaged fruit, as well as the use of beat tray sampling to detect brown marmorated stink bug presence.
Rijal is continuing his work to develop an IPM program for brown marmorated stink bug in almond. As a new pest, insecticides are key for its management, at least until other effective methods such as biological control are developed. Rijal’s extension program increased awareness of brown marmorated stink bug as a pest of almond. He improved grower and pest control adviser knowledge and skill to identify and monitor for this pest. They are also monitoring for brown marmorated stink bug to prevent yield loss in almond.
Grower Brent Barton called Rijal to express his appreciation for the information in a Rijal extension publication. Barton had nut drop in his orchard and initially did not know why it was occurring. He now understands it is because of brown marmorated stink bug feeding and is aware of the areas where brown marmorated stink bug can be found (e.g., near woodpiles and refuse areas). Rijal and Barton are working together to put traps in the orchards to help Barton manage brown marmorated stink bug in his almond orchards.
Growers and pest control advisers contact Rijal when they suspect damage by brown marmorated stink bug and use his extension publications to identify this stink bug and other similar looking stink bugs as well. Pest Control Adviser Eric Leer says Rijal’s timely identification information helped him prevent an unnecessary pesticide application. “The stink bug had been misidentified as a brown marmorated stink bug the day before and we were contemplating the need [for] a lengthy and expensive spray program to control this invasive pest. [Rijal’s information] helped me to easily identify the insect and it became a relatively non-issue as far as pest control is concerned.”