Seasonal Abundance and Synchrony between Laricobius osakensis (Coleoptera: Derodontidae) and its Prey, Adelges tsugae (Hemiptera: Adelgidae), in Japan

Abstract

Laricobius osakensis Montgomery & Shiyake, native to Japan, is being measured as a potential biological control agent of the hemlock woolly adelgid, Adelges tsugae Annand, in the eastern United States. Adelges tsugae, a destructive pest threatening the hemlock ecosystems in the eastern United States, was introduced from Japan. This is the first detailed study of the life history of L. osakensis, A. tsugae, and their interaction in Japan. The seasonal abundance of L. osakensis and A. tsugae was assessed in a field study conducted from December of 2007 to November of 2008 in Hyogo, Nara, and Osaka Prefectures (Japan). The sistentes generation of A. tsugae in Japan matured 2 mo later than that reported in British Columbia, Canada, but 1 and 2 mo earlier than in Virginia and in Connecticut, respectively. Timing of the sexuparae generation occurrence in Japan was similar to that observed in Connecticut and Virginia, but this generation has not been observed in British Columbia. Phenological differences among the various A. tsugae population in the eastern U.S. states and Japan can be explained by temperature differences at the locations. Aestival diapause of the predator L. osakensis coincided with diapausing first-instar A. tsugae sistentes. The start of L. osakensis adult activity, oviposition, and larval development was synchronized closely with sistentes development resumption, sistentes adults close to oviposition, and sistentes adults with eggs, respectively. These results indicate good synchrony between L. osakensis and suitable prey stages of A. tsugae in the native habitat of both species.

First Report on Establishment of Laricobius osakensis (Coleoptera: Derodontidae), a Biological Control Agent for Hemlock Woolly Adelgid, Adelges tsugae (Hemiptera: Adelgidae), in the Eastern U.S.

“…The low number of recoveries in the first year was likely due to the colder than normal winter temperatures in the 2014 and 2015 seasons, which resulted in a significant decrease in adelgid density throughout the range of HWA in the eastern U.S. [27]. The low adelgid populations made it difficult to collect L. osakensis, since other than their occurrence as pupae and aestivating adults, this beetle can only be found directly associated with HWA [11]. With increased winter temperatures the following year, the adelgid populations rebounded.…”

“…To date, L. nigrinus has successfully established and spread throughout the eastern United States [7,9].Laricobius osakensis Montgomery and Shiyake, was discovered in Japan in 2005 from sampling Tsuga sieboldii (Carriere) [10]. It has the potential to be a promising biological control agent because it is a natural predator of the HWA strain present in the eastern United States [1,11]. Both the adults and larvae of L. osakensis feed on and are highly host-specific to HWA.…”

Implications of early production in an invasive forest pest

“…Before December 2015, the earliest first‐instar progredientes were documented in March in Japan (Vieira et al , ) and Georgia (Joseph et al , ), as well as in April in Virginia (Gray & Salom, ; Mausel et al , ), Connecticut (McClure, ) and British Columbia (Zilahi‐Balogh et al , 2003a). First‐instar production in December may indicate late production of sistentes, early development of the progrediens generation, the development of a new generation, or some combination of these.…”

“…(Inouye, 1953; Yukawa & Masuda, ; Sato, ) suggests sexual reproduction, and Tsuga spp. are found hosting parthenogenetic A. tsugae (McClure, ; Sasaji & McClure, ; Vieira et al , ). In its introduced range, where no primary host has been documented, A. tsugae is limited to two parthenogenetic generations (McClure, , , ; Gray & Salom, ; Mausel et al , ; Joseph et al , ) that feed and reproduce exclusively on hemlock.…”

“…Adelges tsugae activity on hemlock is similar in Japan and British Columbia, where A. tsugae endemicity is likely (Havill et al , , ). In Japan (Vieira et al , ), sistens adults are present from December through May, producing eggs from January through May that hatch from March through May. Maturing from May through June, progrediens adults have been documented with sistens eggs in June.…”