Cold Storage Extends Larval Release Windows of Archanara neurica and Lenisa geminipuncta (Noctuidae), Biological Control Agents for Phragmites australis australis

Two biological control agents, <i>Archanara neurica</i> (Hübner) and <i>Lenisa geminipuncta</i> (Haworth) (Lepidoptera: Noctuidae), are being released in Canada for the control of invasive common reed, <i>Phragmites australis australis</i> (Cav.) Trin. Ex Steud (hereafter <i>Phragmites</i>). The release of larvae implanted in cut <i>Phragmites</i> stems is the most reliable way to establish agents at new sites, but the number of larvae that can be used for releases is limited by the short period of time over which egg hatch occurs. We conducted a cold storage experiment to assess whether the timing of egg hatch can be manipulated without affecting hatch success. Additionally, we conducted visual assessments of developing eggs to determine whether hatch timing can be predicted based on early signs of development. Eggs hatched indoors had lower hatch rates than eggs hatched in outdoor conditions. For <i>A. neurica</i> and <i>L. geminipuncta</i>, eggs could be held in cold storage for 11 and 8 weeks, respectively, without affecting hatch rates. Eggs of both species began hatching 4-7 days after the appearance of visible signs of larval development. Manipulating the timing of hatch in <i>A. neurica</i> and <i>L. geminipuncta</i> will increase the number of larval releases that can be conducted during the spring and allow the timing of releases to be optimized.