Advances in mass rearing Pseudophilothrips ichini (Hood) (Thysanoptera: Phlaeothripidae), a biological control agent for Brazilian peppertree in Florida

Authors: Halbritter, Dale; Rayamajhi, Min; Wheeler, Gregory; Leidi, Jorge; Owens, Jenna; Cogan, Carly

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2021
Publication Date: 9/3/2021
Citation: Halbritter, D.A., Rayamajhi, M.B., Wheeler, G.S., Leidi, J.G., Owens, J.R., Cogan, C.A. 2021. Advances in mass rearing Pseudophilothrips ichini (Hood) (Thysanoptera: Phlaeothripidae), a biological control agent for Brazilian peppertree in Florida. Insects. 12(9):790. https://doi.org/10.3390/insects12090790.
DOI: https://doi.org/10.3390/insects12090790

Interpretive Summary: Pseudophilothrips ichini is a recently approved biological control agent for the highly invasive Brazilian peppertree in Florida, USA. Methods for producing large numbers of the thrips are needed to ensure enough thrips are available for field release across the state. Prior to approval for field release in 2019, thrips colonies were kept in small cylindrical cages that fit in limited quarantine space. We developed novel techniques that expanded from small colony maintenance to large-scale production. We first quantified the productivity of the small cylinders, which each produced an average of 363 thrips per generation. Given the amount of maintenance the cylinders required, we tried larger cages to see if greater numbers of thrips could be produced with less effort. Larger acrylic boxes produced an average of 635 thrips per generation. The final advancement was walk-in thrips proof screen cages that each produced an average of 12,527 thrips per generation. Screen cages produced up to 34 times more thrips per enclosure while requiring significantly fewer personnel hours. The large screen cages efficiently produced thousands of thrips weekly, permitting us to sustain mass distribution in the field. The advances made here contribute to the published methods on thrips rearing and are among the few that focus on mass rearing thrips as beneficial insects.

Technical Abstract: Pseudophilothrips ichini is a recently approved biological control agent for the highly invasive Brazilian peppertree in Florida, USA. Prior to approval for field release in 2019, thrips colonies used for host specificity testing have been maintained in small cylinders to fit in restricted quarantine space. This next segment in the classical biological control pipeline is mass production and distribution of P. ichini. To accomplish this, we developed novel techniques that expanded from small colony maintenance to large-scale production. We first quantified the productivity of the small cylinders, which each contained a 3.8 L plant and produced an average of 363 thrips per generation. Given the amount of maintenance the cylinders required, we tried larger cages to see if greater numbers of thrips could be produced with less effort. Acrylic boxes (81.5 x 39.5 x 39.5 cm) each contained two 3.8 L plants and produced an average of 635 thrips per generation. The final advancement was large thrips-proof screen cages (1.8 x 1.8 x 1.8 m) that each held six 11.4 L plants and produced on average 12,527 thrips per generation. Despite multiplication rates being similar among the three cage types, screen cages produced up to 34-fold more thrips per enclosure requiring significantly fewer personnel hours. The large screen cages efficiently produced thousands of thrips weekly, permitting us to sustain mass distribution in the field. The advances made here contribute to the literature on thrips rearing and are among the few that focus on mass rearing thrips as beneficial insects.