- Author: Kathy Keatley Garvey
The insect, a native of Asia, was first detected in the United States (Palm Beach County, Florida) in 1998, and California (San Diego County) in 2008. HLB, the bacterial disease that it transmits, was first detected in Florida in 2005, and in California (Hacienda Heights, Los Angeles County), 2012.
“The ACP has the potential to establish itself throughout California wherever citrus is grown,” according to the California Department of Food and Agriculture (CDFA).
Now an international team of scientists, led by chemical ecologist Walter Leal of the University of California, Davis, has discovered a new lure or male attractant that's more efficient and effective than the current trap surveillance system of yellow sticky traps.
“Our newly discovered lure captures an average of three times more ACP than the current trapping system, the sticky yellow traps,” said Leal, a distinguished professor in the Department of Molecular and Cell Biology and a former chair of the Department of Entomology and Nematology. “And it works in areas with low population densities. This is particularly important in California, because HLB is already established in urban areas and, therefore, trap surveillance systems are at a premium.”
The research, “Laboratory and Field Evaluation of Acetic Acid-Based Lures for Male Asian Citrus Psyllid, Diaphorina citri, is published today (Sept. 9) in Scientific Reports. It can be accessed free online at https://www.nature.com/articles/s41598-019-49469-3.
The 16-member team, which includes scientists from Brazil and Costa Rica and Benjamin Lehan of California State Polytechnic University, Pomona, wrote in their abstract: “Lures are much needed for improving ACP trapping systems for monitoring populations and surveillance. Previously, we have identified acetic acid as a putative sex pheromone and measured formic acid- and propionic acid-elicited robust electroantennographic responses. We have now thoroughly examined in indoor behavioral assays (4-way olfactometer) and field tests the feasibility of these three semiochemicals as potential lures for trapping ACP. Formic acid, acetic acid, and propionic acid at appropriate doses are male-specific attractants and suitable lures for ACP traps, but they do not act synergistically.”
“An acetic acid-based homemade lure, prepared by impregnating the attractant in a polymer, was active for a day,” they wrote. “A newly developed slow-release formulation had equal performance but lasted longer, thus leading to an important improvement in ACP trap capture at low population densities.”
“The disease has ravaged the citrus industry in China and Brazil,” said Leal, a native of Brazil. “In Brazil, about one-fourth of the citrus trees in the state of São Paulo has been eradicated since 2004 as part of an HLB control strategy. Florida has also sustained severe losses.
Now the disease threatens California's citrus growers “Of note, 1,100 findings of HLB in urban, but not in commercial orchards, suggest that the disease is already established in urban areas in California,” the scientists wrote. “Monitoring ACP populations is essential for integrated vector management and, more importantly, for surveillance. One of the challenges for abatement personnel in areas of low ACP densities is to capture the vector to determine infection status so that control strategies can be implemented before HLB is spread. Therefore, the development of trapping systems is at a premium, particularly the discovery of lures for enhancing ACP captures in areas of low populations.”
Earlier, an international team of scientists led by Leal identified the sex pheromone of the Asian citrus psyllid. Leal, a fellow of the Entomological Society of America and the Entomological Society of Brazil, announced the discovery, encompassing six years of research, at the 10th Annual Brazilian Meeting of Chemical Ecology in Sao Paulo in December 2017. (See Bug Squad blog)
Pheromones and other semiochemicals are widely used in agriculture and medical entomology. “Growers use them as lures in trapping systems for monitoring and surveillance, as well as for strategies for controlling populations, such as mating disruption and attraction-and-kill systems,” Leal noted.
In response to the ACP invasion in California, the CDFA has launched an extensive monitoring program to track the distribution of the insect and disease. They check yellow sticky traps in both residential areas and commercial citrus groves, and also test psyllids and leaf samples for the presence of the pathogen.
Survey methods for ACP include visual inspections; sweep netting, and placement of yellow sticky traps in trees in citrus nurseries, commercial citrus-producing areas and residential properties throughout the state, according to the CDFA. They also place sticky traps in California fruit packing houses, specialty markets, retail stores and airports that receive such produce from areas known to be infested with ACP.
CDFA has set up a hotline at (1-800-491-1899) for residents to report suspicious insects or disease symptoms in their citrus trees.
- Author: Kathy Keatley Garvey
More than 2000 scientists are registered to attend the meeting, to be held Sept. 2-6 in Gramado, Brazil.
UC Davis scientists delivering plenary addresses will be Frank Zalom, distinguished professor of entomology, UC Davis Department of Entomology and Nematology and a past president of the Entomological Society of America (ESA); Walter Leal, distinguished professor, UC Davis Department of Molecular and Cellular Biology, and a past chair of the Department of Entomology and Nematology; and Joanna Chiu, associate professor and vice chair, UC Davis Department of Entomology and Nematology. More than 2000 attendees are registered.
On behalf of ESA, Zalom is co-organizing and co-chairing a joint conference with Antonio Panizzi, a past president and international delegate of the Entomological Society of Brazil. That event, to take place the day before the XXVII Congresso Brasileiro and X Congresso Latino-Americano meeting, will involve developing a “Grand Challenge Agenda for Entomology in South America.
Zalom will speak on “The American Experience with the Grand Challenge Agenda in Entomology.” In addition, ESA president Michael Parrella, dean of the College of Agricultural and Life Sciences at the University of Idaho and a former chair of the UC Davis Department of Entomology and Nematology, will provide an update on the 2018 ESA annual meeting, set Nov. 11-14 in Vancouver, B. C. Speakers also will include the presidents of the entomological societies of Argentina, Peru and Brazil.
Leal, a native of Brazil, will present the opening lecture of the joint conference of the XXVII Brazilian Congress and X Latin American Congress of Entomology on “Insect Vectors: Science with Applications in Agriculture and Medicine,” on Sunday, Sept. 2. This will be his fourth opening lecture—a record—at the Brazilian Congresses of Entomology (2004 in Gramado; 2008 in Uberlandia; and 2014 in Goiania). As an aside, legendary entomologist Marcos Kogan previously held the record: he presented two opening lectures, one in 1983 and another in 2002. Both Leal and Kogan (professor emeritus of agricultural entomology, University of Illinois and professor emeritus, Oregon State University) were elected ESA fellows; Leal in 2009 and Kogan in 2016. Zalom received the honor in 2008.
Zalom, an integrated pest management specialist, and former director of the UC Statewide Integrated Pest Management Program (UC IPM) and Chiu, who specializes in molecular genetics of animal behavior, will speak on their research at the joint meeting. Zalom will deliver a plenary address on “Drosophila suzukii in the United States” on Sept. 5, and Chiu will keynote a symposium on Sept. 3; her lecture is titled “Circadian Clock Research Applied to Agriculture and Public Health.” She will give a second lecture: "Drosophila as an Insect Model" on Sept. 3.
The spotted wing drosophila (SWD) is a serious pest of fruit crops. Most drosophila flies feed on spoiled fruits, but SWD prefers fresh fruit (berries and soft-skinned fruits). Read more about SWD on the UC IPM website.