Screening Hybrid Poplar Clones for Susceptibility to Cryptorhynchus lapathi (Coleoptera: Curculionidae)

Abstract

The poplar-and-willow borer, Cryptorhynchus lapathi (L.) (Coleoptera: Curculionidae), is a wood-boring pest of economic importance in irrigated hybrid poplar (Populus spp.) farms in eastern Washington and Oregon. There is no practical insecticide control tactic against either the larval or adult stage of C. lapathi. To assess variability in C. lapathi toward clone preference, we initiated a no-choice study on 180 caged trees that consisted of five clones in a randomized complete block design. C. lapathi was significantly more successful at establishing a population in two clones with Populus trichocarpa X P. deltoides (TxD) parentage (female x male) than in either of two clones with P. deltoides x P. nigra (DxN) parentage (female x male), or a single clone with P. deltoides x P. maximowiczii (DxM) parentage (female X male). There were no significant differences in the rate of weevil development among infested clones, with the exception of DxM trees. Larvae in DxM clones developed on average to the fourth size grouping and those in the two TxD clones developed on average to the fifth size grouping, and this difference was significant. These results corroborate our general damage surveys conducted in the field. Our findings provide growers with the option to choose less susceptible varieties when replanting.

Life History, Development, and Rearing ofEucryptorrhynchus brandti(Coleoptera: Curculionidae) in Quarantine

“…Using Dyar's rule, six instars occur for development of E. brandti larvae (Table 2). This is similar to the closely related species Cryptorhynchus lapathi (L.) (Coleóptera: Curculionidae), which had a mean growth ratio of 0.73 (Hannon et al 2008). Duration of the larval stage was 110 ± 15.0 d. The duration of each individual instar was not able to be determined due to the limitations of sampling for lai-vae under the bark ofthe billets.…”

“…The data indicate that E. brandti had six stadia or "larval groupings." Studies by Hannon et al (2008), on the closely related poplar-and-willow borer [ Cryptorhynchmlapathi (L.) (Coleóptera: Curculionidae) ], found similar results in field-collected beetles and identified six larval groupings. The entire time required for E. brandti larval development from first instar to pupation was «»110.0 ± 15.0 d.…”

Occurrence and development ofEucryptorrhynchus brandtiandE. chinensis(Coleoptera: Curculionidae) onAilanthus altissimatrees subjected to different levels of mechanical damage

“…The authors concluded that this effect was due to antibiosis found in the resistant clones. Hannon, Kittelson, Eaton, and Brown (2008) also reported arrested larval development in Populus maximowiczii clones.…”

Possible Factors of Poplar Susceptibility to Large Poplar Borer Infestation

“…Interestingly, the hybrid P. deltoides × P. balsamifera, descending from two American parents, showed no infestation, highlighting the complexity of genetic influences on pest resistance. The experience of Hannon et al [29] suggests that hybrids with P. deltoides × P. nigra parentage are more resistant to stem borers than P. trichocarpa × P. deltoides or P. trichocarpa × P. nigra parentage.…”