A predator breeding station for augmentative biological control of scolytine crop pests

The square-necked grain beetle, Cathartus quadricollis (Coleoptera: Silvanidae), is a predator of two significant crop pests in Hawaii: the coffee berry borer, Hypothenemus hampei, in coffee and the tropical nut borer, H. obscurus (Coleoptera: Curculionidae: Scolytinae) in macadamia nut. C. quadricollis is also a stored grain pest and is known to respond to its aggregation pheromone (i.e., quadrilure). Field tests were conducted in a macadamia nut orchard using sticky traps to identify the best lure dispenser and trap color based on captures of adult C. quadricollis. When quadrilure was released in different dispenser types, in combination with a fungal volatile blend released from a pouch, we found that a membrane-type quadrilure release dispenser (wafer) was superior to a red septa, gray septa, or open vial dispenser in attracting C. quadricollis. In subsequent tests, the combination of a quadrilure lure and a lure releasing a blend of fungal volatiles caught more C. quadricollis than the quadrilure lure alone. Also, we found that black sticky traps caught more C. quadricollis than did blue, green, red, yellow, white, or clear sticky traps. A predator breeding station consisting of a screened and sheltered enclosure con-taining food (250 g of cracked corn: cornmeal [4:1, w:w] mix) and the membrane-type quadrilure lure was developed to augment predator numbers in coffee and macadamia fields. In the laboratory, stocking a breeding station with 100 C. quadricollis resulted in production and dispersal of about 10,000 adults per station over a four-month period at 25 degrees C. In field tests, use of the quadrilure lure plus a fungal volatiles lure or the quadrilure lure alone were placed in breeding stations in a coffee field to attract naturally occurring wild adults for a five-week period, then returned to the laboratory where they both produced roughly 3,000 adults per station over a five-month period. The predator breeding station was an efficient way to multiply C. quadricollis numbers in the field and could be used to augment biological control of the coffee berry borer in coffee and tropical nut borer in macadamia nut.