Evaluation of pheromone traps for bark beetles and their predators in pine forests in the Kharkiv region

Abstract

Introduction
 Pine stands of many regions have been affected by outbreaks of bark beetles with the dominance of Ips acuminatus (Gyllenhal, 1827) and Ips sexdentatus (B?rner, 1776). In many countries, pheromone traps are produced and used to monitor and suppress native and alien bark beetles. In Ukraine, pheromone traps for catching bark beetles are not produced. The effectiveness of various trap designs and the number of lures for pine bark beetles have not been previously studied in Ukraine. In 2023, within the framework of the FAO project TCP/RER/3801, State Specialized Forest Protection Enterprise ‘Kharkivlisozahyst’ received three types of pheromone traps produced by the Spanish company Sanidad agricola econex s.l. and pheromones intended for the capture of I. acuminatus and I. sexdentatus.
 The study aimed to compare the species composition and abundance of bark beetles and their predators by captures in the different pheromone trap-lure combinations.
 Materials and Methods
 The research was carried out in June – August 2023 in pure mature pine stands in the Vasishcheve subunit (State Specialized Forest Enterprise “Forests of Ukraine”, Branch “Zhovtneve Forestry”). Three types of pheromone traps were placed randomly in six locations of a homogeneous stand, the distance between which was about 50 meters. Type A traps (Funnel) contain 8 funnels, Type B traps are Theyson, and Type C traps are Crosstrap® mini. Depending on the experimental design, the traps contained blades with pheromones of Ips acuminatus or Ips sexdentatus. Blades for I. acuminatus contained 2 and 3 dispensers (commercial names 4C and 5C, respectively), and blades for I. sexdentatus contained 3 and 4 dispensers (commercial names 4C and 5C, respectively). In control treatments, respective traps (A, B, and C) were left empty (without blades). Trapping experiments were carried out from 20 June through 8 August 2023. Trapped insects were collected every 7 days, dried, and sorted. Bark beetles, longhorn beetles, and predators were identified at the species level, and some other insect groups at the family level at least.
 Results and Conclusions
 Five bark beetle species (Curculionidae: Scolytinae), five longhorn beetles (Cerambycidae), five predator species from Histeridae, Cleridae, Nitidulidae, Monotomidae, and Tenebrionidae, as well as several species of Staphylinidae, Carabidae, and Elateridae were captured in traps of three types (A – Funnel; B – Theyson; C – Crosstrap® mini) with pheromones of Ips acuminatus and I. sexdentatus. Target species – Ips acuminatus and I. sexdentatus – accounted for 51% and 31% of all captured beetles, respectively. Their numbers, seasonal dynamics, and proportions depended on the trap type, pheromone, and blade. The highest number of I. acuminatus beetles was captured in Crosstrap® mini traps (C type), and that of I. sexdentatus was found in Theyson traps (type B). An increase in dispenser number provides more captures of I. acuminatus and has no significant influence on captures of I. sexdentatus. The number of Th. formicarius was the lowest in trap B (Theyson) and the highest in trap С (Crosstrap® mini). The number of Th. formicarius captured in traps A and C with the pheromone of I. acuminatus was higher than in the traps with the pheromone of I. sexdentatus. Differences in the captured Th. formicarius beetles in the traps with more dispensers with the pheromone of I. acuminatus are significant, whereas in the traps with the pheromone of I. sexdentatus they are nonsignificant.
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