Hybridization Potential of Two Invasive Asian Longhorn Beetles

Authors: Wang, Xingeng; KEENA, MELODY - Us Forest Service (FS)

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2021
Publication Date: 12/20/2021
Citation: Wang, X., Keena, M.A. 2021. Hybridization potential of two invasive Asian longhorn beetles. Insects. 12(12):1139. https://doi.org/10.3390/insects12121139.
DOI: https://doi.org/10.3390/insects12121139

Interpretive Summary: Asian longhorned beetle (ALB) and citrus longhorned beetle (CLB) are high-risk invasive pests that attack various healthy hardwood trees. These two species have overlapping distributions in their native ranges in China and the Korean peninsula. A related longhorned beetle occurs only in Japan but has been considered to be the same species as CLB (i.e., Japanese CLB or JCLB). We were unable to crossbreed a Chinese ALB population with a Chinese CLB population in the laboratory, but males of a Japanese CLB population crossed successfully with females of a Chinese ALB population to produce viable eggs. Both the Chinese CLB and Japanese CLB populations also crossed successfully, and they should be considered as two subspecies. This suggests that invasion of these currently isolated species (ALB and JCLB) or subspecies (CLB and JCLB) into same regions such as US or Europe could facilitate potential inter- or intra-specific hybridization, which may have significant implications for management programs of these invasive pests.

Technical Abstract: The Asian longhorned beetle (ALB), Anoplophora glabripennis (Motschulsky) and citrus longhorned beetle (CLB), Anoplophora chinensis (Förster) (both Coleoptera: Cerambycidae: Lamiinae), are high-risk invasive pests that attack various healthy hardwood trees. These two species share some similar host plants and overlapping distributions in large parts of their native range in China and the Korean peninsula as well as similar reproductive behaviors. The original Anoplophora malasiaca (Thomson) occurs in Japan and has been synonymized as CLB (hereafter referred to Japanese CLB or JCLB). In this study, a 30-minute behavioral observation of paired adults, followed by a four-week exposure to host bolts, showed that ALB could not cross successfully with CLB. Mating was observed between female CLB and male ALB but not between female ALB and male CLB, no laid eggs hatched. JCLB males crossed successfully with ALB females to produce viable eggs although the overall percentage of hatched eggs was lower than those from conspecific mating pairs. However, ALB males could not cross successfully with JCLB females. CLB and JCLB mated and produced viable hybrid offspring. These results suggest an asymmetrical hybridization between ALB and JCLB, and that both CLB and JCLB might be considered as two subspecies with different hybridization potential with congeneric ALB. Given their potential impacts on ecosystems and many economically important tree hosts, invasion of these originally isolated species (ALB and JCLB) or subspecies (CLB and JCLB) into the same region may facilitate potential hybridization, which could be a potential concern for the management of these two globally important invasive forest pests.