As part of ACIAR the project “Responding to emerging pest and disease threats to horticulture
in the Pacific islands” (HORT 2016 185), Workshops are being held in Samoa and Tonga to
discuss strategies to control the most destructive citrus pest and a recent introduction into the
South Pacific Islands, the Asian Citrus Psyllid (ACP).
The ACP was first recorded in Samoa in 2014 and under the current project, its distribution has
been monitored in collaboration with SROS research colleagues. ACP is now widely distributed
across both Savai’i and Upolu.
Citrus greening disease, or huanglongbing (HLB), is considered the principal threat to the global
citrus industry, causing severe yield losses and reductions in fruit quality. The disease is caused
by the bacterium Candidatus Liberibacter spp., a pathogen that is vectored by the Asian Citrus
Psyllid (ACP) (Diaphorina citri Kuwayama (Hemiptera: Psyllidae)).
The wide distribution of an established ACP population in Samoa presents a significant threat to
growers nationally and represents a significant biosecurity threat to the region. Both the pest
and disease originate from Asia, the native range of citrus.
Dr. David Morgan from California’s Department of Food and Agriculture will be presenting
workshops on the control of the ACP with particular emphasis on the use of biological control
as a pest management strategy. Biological control has a long and successful history of success
when used against invasive pests on islands. Dr. Morgan is California’s Primary State Scientist in
the field of biological control and oversees the state’s ACP biological control program.
The first day of the workshop (30 th July 2024) will target all stakeholders in the citrus industry in
Samoa and will provide background to the problem, describe research underway elsewhere to
control the insect pest and the disease and discuss surveillance methods and biological control.
The second day (31 st July 2024) will focus on biological control and this will be followed by field
visits to citrus orchards on day three (1 st Aug 2024). On the final day (2 nd Aug 2024) of the
workshop, Dr Morgan will introduce the participants to the glassy winged sharpshooter,
another invasive pest in the region, and describe how it has been managed in parts of its
invasive range.

The workshop will conclude with a discussion session in which course participants will be able
to propose what the next steps need to be.