Cuphea lanceolata and Cuphea ignea seed increase using three pollinators in insect-proof cages in the field

Authors: Abel, Craig; VAN ROEKEL, JOHN - Retired ARS Employee; WILSON, RICHARD - Retired ARS Employee

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2018
Publication Date: 3/21/2019
Citation: Abel, C.A., Van Roekel, J.W., Wilson, R.L. 2019. Cuphea lanceolata and Cuphea ignea seed increase using three pollinators in insect-proof cages in the field. Southwestern Entomologist. 44(1):95-98. https://doi.org/10.3958/059.044.0110.
DOI: https://doi.org/10.3958/059.044.0110

Interpretive Summary: Medium-chain fatty acids are important for industrial uses. Most of these fatty acids are obtained from coconut and oil palm imported from the tropics. Many species of Cuphea are rich in medium-chain fatty acids and may provide a temperate source for industry use. However, there are several agronomic limitations to the commercial production of Cuphea, e.g. seed shattering, seed dormancy, and indeterminate plant growth. Because many Cuphea species require insect pollination, there is a need to identify pollinators to support breeding and seed production efforts. The objective of this study is to compare honey bees, bumble bees, and horned-face bees as pollinators of Cuphea lanceolata and Cuphea ignia grown under insect-proof field cages. For Cuphea lanceolata, more seed was produced using honey bees than the no-insect control and honey bees were as effective as bumble bees and horned-face bees. For Cuphea ignia, more seed was produced using honey bees than the use of bumble bees, horned-face bees, and the no-insect control. This information will be useful for researchers regenerating Cuphea seed under controlled pollination conditions and for plant breeding efforts to develop this new crop.

Technical Abstract: Seed oil from many Cuphea (Lythraceae) species are abundant in medium-chain fatty acids (C8-C14). These fatty acids are valuable to industry and mostly obtained from tropical plant sources. Cuphea could provide a valuable temperate plant source of these fatty acids but there are agronomic limitations to its commercial production. Many Cuphea spp. are entomophilous so finding suitable pollinators will enhance development of the crop. In this study, the pollinating ability of three insects, Apis mellifera L., honey bee; Bombus bimaculatus Cresson, bumble bee; and, Osmia cornifrons (Radoszkowski), horned-face bee; were tested on Cuphea lanceolata W.T. Aiton, and Cuphea ignia A. DC, grown under insect-proof field cages. Based on harvested seed weight, the honey bee was an efficient pollinator of C. lanceolata with significantly more seed produced (40.9g) than the no-pollinator control (9.8g). The honey bee treatment was not significantly different to the bumble bee (20.7g) and the horned-face bee (25.6g) treatments. The honey bee was also an efficient pollinator of C. ignia with significantly more seed produced than all other pollinator treatments. Bombus spp. are considered excellent pollinators of Cuphea, however, our results indicate B. bimaculatus was an inefficient pollinator of C. ignia grown under field cages. Cuphea seed weight per 100 seed sample, an indicator of seed quality, was not significantly different across all pollinator treatments.