ARS | Publication request: Population growth and development of the psocid Lepinotus reticulatus at constant temperatures and relative humidities

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 27, 2007
Publication Date: February 28, 2008
Citation: Opit, G.P., Throne, J.E. 2008. Population growth and development of the psocid Lepinotus reticulatus at constant temperatures and relative humidities. Journal of Economic Entomology 101: 605-615.

Interpretive Summary: Psocids, which are minute insects that are often called booklice, are an emerging problem in grain storages, grain processing facilities, and product warehouses in the United States and many other countries. A little studied psocid species, Lepinotus reticulatus, is a pest of stored commodities throughout the world. Development of an effective pest management program for L. reticulatus is dependent on having sound knowledge of its biology. We determined that L. reticulatus requires warm temperatures and humid conditions to multiply rapidly. We determined the duration of the life cycle of L. reticulatus at different temperatures to develop predictive equations for estimating development time of the different stages of this psocid. This information on the biology of this pest will be useful for improving management of L. reticulatus.

Technical Abstract: We investigated the effects of temperature and relative humidity on population growth and development of the psocid Lepinotus reticulatus Enderlein. Part of this study assessed the effects of marking psocids using methylene blue, chalk powder, and fluorescent powder to differentiate nymphal stages during development. We found that marking psocids using methylene blue increased mortality and took twice as long to accomplish compared to marking using fluorescent powder. Using chalk powder shortened the duration of third and fourth nymphal instars. Marking psocids using fluorescent powder had no effect on mortality or duration of nymphal instars. Therefore, we recommend using fluorescent powder for marking psocids. L. reticulatus did not survive at 32, 43, and 55% RH, while populations increased from 22.5 to 32.5°C at 75% RH. The largest population growth was recorded at 30 and 32.5°C, while only 9% of nymphs developed to adults and populations declined at 35°C. We developed temperature-dependent developmental equations for eggs, combined nymphal, and combined immature stages. These equations showed optimal temperatures for the development of these stages to be 32.3, 34.5, and 34.4°C, respectively; development at these temperatures was completed in 6.3, 16.7, and 23.3 d, respectively. Our study shows that psocids which eat cast skins develop faster than those that do not, and this effect is more pronounced at lower temperatures. These data give us better understanding of L. reticulatus population dynamics and can be used to help optimize management of this psocid.