Emerging Pest Alert
Agrilus mali: a pest of apples
Agrilus mali: a pest of apples
Scientific Name: Agrilus mali
Common Name: apple buprestid beetle
Title: Agrilus mali: a pest of apples
Significance: Agrilus mali is a wood-boring beetle and is a significant pest in China and Russia where it damages and occasionally kills apple trees in nurseries, orchards, and natural settings (CABI, 2017; Cui et al., 2015; Nikritin, 1994; Sun et al., 1979). Larval feeding damages the sapwood of shoots, branches, and the trunk. This feeding can cause dry, cracked bark; stem dieback; and defoliation. These symptoms can weaken or kill the tree, depending on the extent of the infestation (CABI, 2017; Cui et al., 2015; Sun et al., 1979). Agrilus mali prefers weakened host trees (CABI, 2017).
In parts of China, A. mali was primarily a pest of wild apple trees, but moved into agricultural settings when orchards were established on mountain sides (Sun et al., 1979). Agrilus mali has been characterized as a highly destructive trunk-borer in fruit trees (Cui et al., 2015). For example, in 2006, A. mali damaged 45 percent of the apple orchards in Jianzha County in Qinghai, China (Cui et al., 2015). Apple orchards with heavy infestations had damage in 60 percent of the trees, and the mortality rate was 20 percent (Cui et al., 2015). In another study from 1974 and 1975, the total apple area damaged by A. mali in Fengxian County, Shaanxi Province, was 13,162 mu (2168 acres or 878 hectares), which was 50 percent of the total apple area of the county (Sun et al., 1979). The average apple tree infestation rate was 34 percent and there were 230 dead trees (Sun et al., 1979). Although “damage” in the apple orchards is described, we did not find specific information regarding yield losses. In wild settings, A. mali damage on apples has been described as “extremely injurious”, and trees are said to have “seriously suffered from the insect”(Yang et al., 2016). For example, A. mali colonized over half of the wild apple forests in the Tianjin district of Xinjiang, China between 1995 and 2003, and was considered the most damaging apple pest (Cui et al., 2015). In another study in Xinjiang, A. mali caused a 30 percent reduction in wild Malus sieversii plantings and the wild host populations “seriously suffered” (Yang et al., 2016). Additional descriptions of A. mali damage in wild apple trees include the terms “serious” (Cui et al., 2015) and “significant” (Yi et al., 2016). No evidence was found of A. mali causing economic damage in apricots, hawthorn, peaches, or pears.
Issues of Concern:
To date, A. mali has not been reported from North America.
There is strong evidence that A. mali is injurious to apple trees.
Pathways: Agrilus mali lives inside the wood of its hosts and can move long distances in infested plant material. It was introduced into new agricultural and natural areas in China in infested seedlings (CABI, 2017; Ying et al., 2004) and introduced into the Xinjiang region of China in infested plants (Zhang and Jiang, 2016).
Apple and pear wood is sometimes used to make furniture (HowStuffWorks, 2017; Hummer and Janick, 2009), and since A. mali lives inside the wood, furniture is another possible pathway for A. mali introduction, though the frequency or likelihood of this occurring is unknown.
It is also unknown how frequently, if at all, that host wood is used for wood packing material, so there is a high uncertainty whether wood packing material is a likely pathway for the introduction of A. mali.
Hosts: Species of Malus are the primary hosts for A. mali (EPPO, 2017; Ying et al., 2004) and it has a preference for M. halliana (Hall crabapple) (Cui et al., 2016). Agrilus mali is also reported on the following plant species: Crataegus spp. (hawthorn), Malus spp. (apple), M. domestica (orchard apple), M. prunifolia (plumleaf crabapple), M. pumila (paradise apple), M. sieversii (wild apple), M. spectabils (assumed to be M. spectabilis) (Asiatic apple), M. yunnanensis (Yunnan crabapple), Prunus persica(peach), Prunus armeniaca (Armenian plum, apricot), Pyrus pyrifolia (sand fruit, assumed to be sand pear), and Pyrus spp. (pear) (Cui et al., 2015; Cui et al., 2016; Jendek and Grebennikopv, 2011; Jendek and Polakova, 2014; NRCS, 2017; Sun et al., 1979; Wang et al., 2014). In a paper translated from Chinese, hawthorn and sand pear were listed by Cui et al. (2015) as main hosts, but these species were not found in other sources, indicating uncertainty regarding their host status for A. mali. The following A. mali hosts are erroneous: Juglandaceae - Juglans regia (English walnut) and Salicaceae – Salix spp. (willow) (Jendek and Grebennikopv, 2011).
Distribution: China, North Korea, South Korea, Mongolia, and eastern Russia (EPPO, 2017; Jendek and Grebennikopv, 2011; Nikritin, 1994; Zhang and Jiang, 2016).
It is uncertain whether A. mali occurs in Japan. While there are sources of information that report A. mali in Japan (Clausen, 1931; Nikritin, 1994; and Zhang and Jiang, 2016), a comprehensive revision of the genus Agrilus for East Asia (Jendek and Grebennikopv, 2011) and key Japanese sources of information (Kyushu University, 2018; Umeya and Okada, 2003) do not list A. mali as occuring in Japan.
Detection Strategies: Symptoms of A. mali larval feeding (e.g., feeding tracks, cracked bark, and depressions) are visible to inspection (CABI, 2017). Shoots and stems should be inspected from early spring through the crop production season (CABI, 2017). No evidence was found that traps or lures have been developed to detect A. mali; however, research on A. mali biology has begun that could lead to monitoring and control strategies that use semiochemicals (Yi et al., 2016).
CABI. 2017. Crop Protection Compendium. Commonwealth Agricultural Bureau International (CABI). http://www.cabi.org/cpc/.
Clausen, C. P. 1931. Insects Injurious to Agriculture in Japan. United States Department of Agriculture, United States Government Printing Office, Washington DC. 1-115 pp.
Cui, C., Z. Yi, M. Wang, D. Liu, S. Liao, and Xu. 2016. Maturing feeding preference of adult Agrilus mali and related host plant leaf volatiles [Translated from Chinese to English]. Scientia Silvae Sinicae 52(11):96-106.
Cui, X., D. Liu, and A. Liu. 2015. Research progress in integrated management of Agrilus mali [Translated from Chinese to English]. Plant Protection 41(2):16-23.
EPPO. 2017. Agrilus mali. European and Mediterranean Plant Protection Organization (EPPO) https://gd.eppo.int/.
HowStuffWorks. 2017. A Guide to Furniture Woods. HowStuffWorks. Last accessed August 21, 2017, http://home.howstuffworks.com/home-improvement/home-diy/furniture-restoration/guide-to-furniture-woods-ga1.htm.
Hummer, K. E., and J. Janick. 2009. 1. Rosacea: Taxonomy, Economic Importance, Genomics. Pages 1-17 in K. M. Folta and S. E. Gardiner, (eds.). Genetics and Genomics of Rosaceae. Springer Science+Business Media, LLC
Jendek, E., and V. Grebennikopv. 2011. Agrilus (Coleoptera, Buprestidae) of East Asia. Jan Farkac, Prague. 362 pp.
Jendek, E., and J. Polakova. 2014. Host plants of world Agrilus (Coleoptera, Buprestidae). Springer, Ontario, Canada. 706 pp.
Kyushu University. 2018. Mokuroku – A Check List of Japanese Insects Database. Faculty of Agriculture, Kyushu University, Fukuoka, Japan. http://konchudb.agr.agr.kyushu-u.ac.jp/mokuroku/.
Nikritin, L. M. 1994. Apple buprestid beetle [Abstract; Translated from Russian to English]. Zashchita Rastenii 3:47-48.
NRCS. 2017. The PLANTS Database. United States Department of Agriculture, Natural Resources Conservation Service (NRCS), The National Plant Data Center. http://plants.usda.gov.
Sun, Y. C., Y. Y. Liang, and H. Sun. 1979. Studies on the apple buprestid (Agrilus mali Mats.) in Shensi [Translated from Chinese to English]. Journal of Northwest College of Agriculture 3:47-56.
Umeya, K., and T. Okada. 2003. Agricultural Insect Pests in Japan. Zenkoku Noson Kyoiku Kyokai, Tokyo, Japan. 1203 pp.
Wang, Z., Z. Yang, Y. Zhang, X. Wang, Y. Tang, and Q. Sun. 2014. Biological control of Agrilus mali (Coleoptera: Buprestidae) by applying four species of bethylid wasp (Hymenoptera:Bethylidae) on Malus sieversii in Xinjiang [Translated from Chinese to English]. Scientia Silvae Sinicae 50(8):97-101.
Yang, M., F. Li, H. Long, W. Yu, X. Yan, and B. Liu. 2016. Ecological Distribution, Reproductive Characteristics, and In Situ Conservation of Malus sieversii in Xinjiang, China. HortScience 51(9):1197-1201.
Yi, Z., D. Liu, X. Cui, and Z. Shang. 2016. Morphology and Ultrastructure of Antennal Sensilla in Male and Female Agrilus mali (Coleoptera: Buprestidae). Journal of Insect Science 16(1):1-10.
Ying, J. I., J. I. Rong, and R. X. Huang. 2004. Invasive species - Agrilus mali Matsumura and damage in Xinjiang [Translated from Chinese to English]. Xinjiang Agricultural Sciences 41(1):31-33.
Zhang, L., and Z. Jiang. 2016. Unveiling the status of alien animals in the arid zone of Asia. PeerJ 4(e1545):1-29.