Hybridization Potential of Two Invasive Asian Longhorn Beetles

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 ranges 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 JCLB). In this study, a 30-min behavioral observation of paired adults, followed by a four-week exposure to host bolts, showed that ALB could not successfully cross 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 successfully crossed 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 successfully cross with JCLB females. CLB and JCLB mated and produced viable hybrid offspring and the hybrid F1 offspring eggs were fertile. 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 geographically isolated species (ALB and JCLB) or distant 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. Further studies are needed to determine if fertile hybrid offspring are capable of breeding continually or backcrossing with parental offspring successfully.

Differences in Male Mate Recognition between the Invasive Anoplophora glabripennis (Coleoptera: Cerambycidae) and Japanese Native A. malasiaca

“…This result supports the results of Sunamura et al [ 36 ] who reported that approximately 50% of Japanese A. chinensis (= A. malasiaca ) males attempted to copulate with A. glabripennis females. They also support an account that confirmed mating behavior in four A. glabripennis female– A. malasiaca male pairs (16%, N = 25) and none of the A. malasiaca female– A. glabripennis male pairs (0%, N = 25) by Wang and Keena [ 35 ].…”

“…Wang and Keena [ 35 ] conducted their experiments using the following individuals: an A. glabripennis colony was established from beetles that were collected in 1999 in Chicago. The A. malasiaca colony used consisted of 16th, 17th, and 18th laboratory generations of an invasive Italian population, captured in Japan.…”

“…Anoplophora glabripennis , A. malasiaca, and the related A. chinensis have been reported to have common volatile pheromones [ 23 , 24 , 25 , 26 , 27 ], whereas no common contact pheromone compounds have been reported [ 26 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. Wang and Keena [ 35 ] investigated the hybridization potential among A. glabripennis, A. chinensis, and A. malasiaca using 4-week laboratory crossing experiments. Egg laying, hatching, and development were observed.…”

Is there hybridization between 2 species of the same genus in sympatry?—The genetic relationships between Anoplophora glabripennis, Anoplophora chinensis, and putative hybrids

“…There appears to be some post-copulatory reproductive isolation between ALB and CLB because they copulated and oviposited, but no hatch was observed. Wang and Keena (2021) also confirmed that ALB collected from China could not successfully cross with CLB from China, which is consistent with our results. This provides customs and pest management evidence to classify the morphological variant that have bumps on the anterior portion of the elytra as ALB.…”

“…If hybridization does occur, mingling of these traits may allow hybrids to invade areas not currently at risk for either ALB or CLB. Wang and Keena (2021) conducted ALB and CLB species reciprocal crossing experiments in the laboratory, they found CLB from China did not cross successfully with ALB, but Anoplophora malasiaca (Japanese citrus longhorn beetle; JCLB) males crossed successfully with ALB females to produce eggs. JCLB is from Japan and has recently been synonymized with CLB.…”