Laboratory Rearing Methods for the Soybean Tentiform Leafminer (Lepidoptera: Gracillariidae), a New Pest of Soybean

Soybean tentiform leafminer (STL), Macrosaccus morrisella (Fitch) (Lepidoptera: Gracillariidae), is a leaf-mining microlepidopteran native to North America that was recently discovered feeding on soybean, Glycine max (L.) Merr., in Canada and the United States. A laboratory rearing system for STL was developed on live soybean plants. The methods for continuous rearing or cyclic (i.e., generational) production of insects are described herein. All rearing was performed in a walk-in environmental chamber at 25 °C (±2 °C), with ~70% relative humidity and a photoperiod of 16:8 (L:D). Adults of STL were allowed to oviposit on clean soybean plants in an oviposition cage. Soybean plants with STL eggs were maintained in a separate immature-development cage for a total of ~2.5 weeks, passing through the egg stage (3–4 days), larval development through the serpentine mine stage (4–6 days), blotch mine stage (5–6 days), and tentiform mine stage to adult emergence (7–10 days). Plants in the tentiform mine stage were then trimmed and transferred to a separate cage until adult emergence, typically beginning 19–23 days after egg oviposition. The methods described allowed for the successful rearing of STL, producing a steady supply of STL adults or plants infested with immature STL. The methodology can be modified to fit the needs of various research projects.