Evaluation of insecticides for protecting Arizona cypress (Cupressus arizonica) and one-seed juniper (Juniperus monosperma) from attack by Phloeosinus bark beetles

We evaluated the effectiveness of carbaryl, bifenthrin, and permethrin in protecting Arizona cypress (Cupressus arizonica) and one-seed juniper (Juniperus monosperma) from attack by two bark beetles (Phloeosinus spp.). Spray formulations of 2.0% carbaryl (Sevin SL®), 0.03% and 0.06% bifenthrin (Onyx®), and 0.19% permethrin (Permethrin Plus C®) were assessed on bolts (sections of logs) of Arizona cypress for their effectiveness in preventing Phloeosinus cristatus attack and colonization. P. cristatus broods were produced in all of the Arizona cypress control bolts. Bifenthrin provided ≥80% and ≥70% protection by the 0.06% and 0.03% formulations, respectively, whereas 0.19% permethrin and 2.0% carbaryl treatments provided <70% protection. Insecticide sprays (1.0% carbaryl, 0.03% and 0.06% bifenthrin, and 0.19% permethrin) were tested for prevention of P. scopulorum neomexicanus attack and colonization on one-seed juniper bolts. Bark beetle galleries were present in 62.5% of the one-seed juniper control bolts. Data on the presence versus absence of P. scopulorum neomexicanus galleries indicated that the 0.03% and 0.06% bifenthrin and 0.19% permethrin treatments provided ≥90% protection and the 1.0% carbaryl spray was ≥80% effective at preventing colonization. The 0.06% bifenthrin formulation provided the best protection against both species of Phloeosinus beetles.