An evaluation of plant genotypes for rearing Asian citrus psyllid (Hemiptera: Liviidae)

Authors: Hall, David; Hentz, Matthew

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2016
Publication Date: 9/1/2016
Citation: Hall, D.G., Hentz, M.G. 2016. An evaluation of plant genotypes for rearing Asian citrus psyllid (Hemiptera: Liviidae). Florida Entomologist. 99:471-480.

Interpretive Summary: The Asian citrus psyllid (ACP)is the vector of citrus huanglongbing disease (also known as citrus greening). Many research endeavors on the psyllid are dependent on a steady supply of ACP, which can be facilitated using a laboratory or greenhouse colony maintained on a host plant. We evaluated/compared nine plant genotypes as host plants for rearing the psyllid. Information was obtained on plant architecture, growth flush production, and psyllid production. Pruning was investigated as a method of increasing psyllid production. Quality control variables assessed included gender ratios and psyllid morphology, notably wing deformities. Entomologists setting up new psyllid rearing programs, or those refining programs currently in operation, will benefit from this information.

Technical Abstract: The Asian citrus psyllid (ACP) is the vector of bacteria responsible for a serious citrus disease known as huanglongbing (also known as citrus greening disease). Many research endeavors on ACP are dependent on a steady supply of ACP, which can be facilitated using a laboratory or greenhouse colony maintained on a host plant. The choice of a plant species may be influenced by the flushing characteristics of a plant, particularly if the goal is to produce large numbers of ACP. This is because ACP is dependent on flush (=new young leaves) for reproduction. Plants can be trimmed to stimulate flush growth. We studied the flushing characteristics of nine plant genotypes known to be highly susceptible to ACP infestations: Afraegle paniculata, Bergera koenigii, Citrus aurantiifolia, Citrus macrophylla, Citrus maxima, Citrus medica, Citrus reticulata, Citrus taiwanica, and Murraya exotica. When the plants were trimmed at seven months after planting, the following produced the greatest number of flush shoots (e.g., a daily peak of 10 to 19 shoots suitable for oviposition per plant): B. koenigii, C. aurantiifolia, C. macrophylla, and M. exotica. Pruning plants once or twice prior to a final trimming at seven months after planting did not increase the number of flush shoots produced per plant for any of the genotypes. At average air temperatures of 28 to 30 degrees Celsius, each genotype began producing flush within about five days after trimming. Among the genotypes that produced the largest numbers of flush shoots, in one experiment peaks in numbers of flush shoots suitable for oviposition generally occurred sooner after trimming C. macrophylla (peak at seven to nine days) than B. koenigii, C. taiwanica, or M. exotica (peaks at nine to 11 days), while in a second experiment peaks in flush counts occurred at about the same time among these genotypes (peaks at about nine days). Number of ACP produced per flush shoot was assessed on five genotypes: B. koenigii, C. aurantiifolia, C. macrophylla, C. taiwanica, and M. exotica. Although some significant differences among the genotypes were observed with respect to when new adults first began to emerge and when peak emergence occurred, the differences were relatively small (in the order of a day or two). During a winter experiment, significantly greater numbers of new adults per flush shoot developed on C. aurantiifolia (30 per flush shoot) than on C. taiwanica or M. exotica (nine per shoot on these genotypes). Greater numbers per flush shoot (29 to 91) developed during experiments conducted during warmer weather, with no significant differences among plant genotypes at the sample sizes studied.