Ips sexdentatus Mass-Trapping: Mitigation of Its Negative Effects on Saproxylic Beetles Larger Than the Target

Research Highlights: We investigated the negative effects of bark beetle mass trapping, especially non-target catches among the target’s natural enemies. Slot traps modified with mesh screen and escape windows were tested to improve their selectiveness. Background and Objectives: Two of the main natural enemies of bark beetles, Thanasimus formicarius (L.) and Temnoscheila caerulea (Olivier), are frequently trapped in high numbers in Ips sexdentatus (Böerner) pheromone traps, along with other saproxylic insects; this may lead to much larger pest populations in the successive 4–20 beetle generations. From 2016–2019, during I. sexdentatus mass-trapping in a pine forest of Tuscany (Italy), non-target catches were tallied. Trap modifications were evaluated to mitigate non-target catches, especially those concerning bark beetles’ natural enemies. Materials and Methods: A total of 25 bark-beetle slot traps were placed about 75 m apart in a pine stand infested by I. sexdentatus. Traps were baited with I. sexdentatus aggregation pheromone, whose main components are ipsenol, ipsdienol, and 2-methyl-3-buten-2-ol. Catches were collected every 10 days from March to December. In 2019, 13 traps were modified by applying a 6-mm mesh screen on top of the collection container and by providing three 60 mm × 8 mm escape windows immediately above the screen. These “modified traps” and their captures were considered separately from the 12 remaining “standard traps.” All bark beetle species were recorded, as well as all beetle species > 8 mm. Results: Overall, target catches amounted for <10% of the total beetle catches. The most-collected species was the bark beetle Orthotomicus erosus Wollaston. Trap modification allowed the escape of larger species, resulting in the reduction of the average size of caught specimens. Even though non-target catches among predators were still high, the proportion of major predators (T. formicarius and T. caerulea) to bark beetles showed a statistically significant reduction of predator catches in modified traps, an encouraging outcome. Conclusions: Trap modifications may mitigate the problem of non-target catches during mass trapping, especially reducing catches of beetle species larger than the target. However, the key is to schedule mass trapping only during those seasons when the target adults are more active than the main predator adults, thus limiting their catches and, consequently, the negative effects on pest management and biodiversity.

Depredadores de escarabajos de la corteza (Coleoptera) en la región de Balikesir de Turquía

El objetivo de este estudio fue determinar la diversidad de los depredadores de los escarabajos de la corteza en los bosques de coníferas de la provincia de Balıkesir en Turquía. Se establecieron seis parcelas que contenían cinco trampas de feromonas y dos trampas de troncos. Se encontraron ocho especies de depredadores de escarabajos de corteza: Aulonium ruficorne (Olivier, 1790), Clerus mutillarius Fabricius 1775, Corticeus fraxini (Kugelann, 1794), Paromalus parallelepipedus (Herbst, 1792), Platysoma elongatum (Thunberg, 1782), Raphidia ophiopsis Linnaeus 1758, Temnochila caerulea (Olivier, 1790) y Thanasimus formicarius (Linnaeus, 1758), pertenecientes a seis familias: Cleridae, Trogossitidae, Laemophloeidae, Tenebrionidae, Zopheridae, Histeridae, Raphidiidae. También se describe en cuáles galerías de escarabajos se encontraban estos depredadores.

Učinkovitost suhih i mokrih naletno barijernih Theysohn® feromonskih klopki u lovu smrekovih potkornjaka Ips typographus L. i Pityogenes chalcographus L.

Istraživanjem učinkovitosti suhih i mokrih Theysohn® naletno barijernih feromonskih klopki došlo se do novih spoznaja značajnih za monitoring populacija smrekovih potkornjaka – Ips typographus i Pityogenes chalcographus. Tijekom 2014. godine 12 mokro-suhih parova crnih Theysohn® naletno barijernih feromonskih klopki postavljeno je u dvije g. j. UŠP Gospić na različitim nadmorskim visinama. Šest parova klopki postavljeno je u g.j. Žitnik na 500 metara nadmorske visine, a preostalih šest na nadmorskoj visini od 1100 metara u g.j. Štirovača u blizini nacionalnog parka Sjeverni Velebit. Između testiranih klopki nije utvrđena statistički značajna razlika broja ulovljenih potkornjaka, iako je suha feromonska klopka ulovila veći broj jedinki smrekovog pisara i šesterozubog smrekovog potkornjaka. Mokra i suha feromonska klopka pokazale su jednaku selektivnost prema predatorskoj entomofauni – Thanasimus formicarius i Nemozoma elongatum. U suhim feromonskim klopkama utvrđena je redukcija broja ulovljenih potkornjaka djelovanjem predatora. Kod vrste T. formicarius uočena je mogućnost bijega iz suhih feromonskih klopki. Rezultati provedenog istraživanja omogućuju racionalniji pristup monitoringu populacija smrekovih potkornjaka sustavom suhih i mokrih naletno barijernih Theysohn feromonskih klopki.

The alpha-cypermethrin coated net for protecting Norway spruce wood against bark beetles (Curculionidae, Scolytinae)

The study estimated the efficacy of a net coated with alpha-cypermethrin used to protect Norway spruce [Picea abies (L.) H. Karst] wood against bark beetle infestations. The inside of the net was coated with 100 mg/m2 of alpha-cypermethrin. The studies carried out in 2010 and 2011 took place in southern Poland in the Beskid Żywiecki and Beskid Sądecki mountains in P. abies stands threatened by Ips typographus (Linnaeus, 1758). The research material consisted of wood logs taken off of 70–80-year-old P. abies trees. The logs were wrapped in the net in the early spring before spring swarming of bark beetles. The unwrapped logs were considered as the study controls. An evaluation of the treatments was performed after 2 months. The evaluation was based on the counting of bark beetles galleries found after removing the bark from the wrapped and unwrapped logs. There were no insect galleries on the wrapped logs. The net was a barrier, on which bark beetles died. About 10 dead I. typographus beetles were found on 0.01 m2 of the net surface. On the bark from the unwrapped-control logs there were 3,156 galleries/entrance holes of bark beetles, in total, of which 73% belonged to I. typographus, 13% to Pityogenes chalcographus (Linnaeus, 1761), and almost 10% to Xyloterus lineatus (Oliv.). These results indicated the high efficacy of the net coated with alpha-cypermethrin used for the protection of Norway spruce wood against the bark beetles. At the same time, the net was found to have a negative effect on non-target entomofauna, mainly Hylobius spp., Thanasimus formicarius (L.), and Tetropium castaneum (F.). However, the use of a net did not affect other predatory (Carabidae) and parasitic (Ichneumonidae and Tachinidae) entomofauna.

Effect of insecticide-treated trap logs and lure traps for Ips typographus(Coleoptera: Curculionidae) management on nontarget arthropods catching in Norway spruce stands

The numbers of nontarget arthropods captured by Theysohn pheromone traps (TPTs) and insecticide-treated tripod trap logs (TRIPODs) were compared; both kinds of traps were baited with pheromone lures Pheagr IT for Ips typographus. In 2010, 15 TPTs and 15 TRIPODs were deployed (with a 10-m spacing) in a forest in the northeastern Czech Republic. The TPTs and TRIPODs were inspected weekly during the entire period of I. typographus flight activity (30 April&ndash;1 October). The TRIPODs were sprayed with Vaztak 10 SC insecticide every 7 weeks; at each spraying, the pheromone evaporators were renewed. Higher numbers of entomophagous arthropods, including the predacious beetles Thanasimus formicarius and T. femoralis, were captured by the TRIPODs than by the TPTs. The number of Thanasimus spp. captured by TRIPODs was especially high at the end of April. The efficacy of TRIPODs for the control of I. typographus could be maintained while the kill of nontarget organisms could be reduced by deploying the evaporators 1 week later (in early May rather than in late April) in relation to the recommended date of dispenser installation. &nbsp;

Contribution to knowledge of Hylesinus fraxini (Panzer, 1779) (Coleoptera: Scolytidae) natural enemies from Northern Moravia (Czech Republic)

Predation by natural enemies was studied as mortality factors of <I>Hylesinus fraxini</I> in 2006–2007. Predation by birds was not recorded and predation rate by insect reached 0.1%. Only one insect predator was reared – <I>Thanasimus formicarius</I> (Linnaeus, 1758). The total rate of parasitism was 54.0%. At least 8 species of parasitoids from the order Hymenoptera were recorded. The most abundant parasitoid was <I>Eurytoma morio Boheman</I>, 1836 (44.1% from the total number of all reared parasitoids; 23.8% of the total mortality), subsequently <I>Eurytoma arctica</I> Thomson, 1876 (31.7%; 17.1%), <I>Cheiropachus quadrum</I> (Fabricius, 1787) (12.8%; 6.9%), Braconidae (6.3%; 3.4%), <I>Rhaphitelus maculatus</I> Walker, 1834 (3.9%; 2.1%), <I>Mesopolobus</I> sp. (0.5%; 0.3%), were not identified Pteromalidae (0.5%; 0.3%) and <I>Tetrastichus</I> sp. (0.2%; 0.1%).