Increasing temperatures affect multiyear life cycle of the outbreak bush-cricket Barbitistes vicetinus (Orthoptera, Tettigoniidae)

Although outbreaks of rare species are unusual, several insect species have become emerging pests probably due to the ongoing environmental changes. Barbitistes vicetinus was first described in 1993 as an endemic bush-cricket of north-east Italy and was considered rare until 2008, when it became an established pest, causing severe damages to forests and crops. The possible role of temperature in changing its life cycle has still to be fully understood. Here, we explored the effect of summer temperature on egg diapause and the effect of winter temperature on egg survival. Field observations showed that the proportion of embryos that can complete development at the end of summer ranged from zero to nearly 90% depending on summer temperatures. A substantial shift in the rate of development from 20% to nearly 80% occurred in a thermal range of about 1 °C. On the contrary, overwinter egg survival was high and constant (90%) across a wide range of winter temperatures that go well beyond both the cold and warm thermal limits of the current species range. Overall, the results suggest a potential key role of summer temperature warming on the outbreak propensity of this species that is able to switch from a multiyear to an annual life cycle with just a 1-2 °C warming.

Effect of summer temperature on prolonged diapause of Tettigoniidae (Orthoptera) under realistic field conditions

To face recurrent temperature changes, tettigoniids inhabiting temperate climates overwinter as eggs in a diapause stage, being able to postpone embryogenesis for one or more years. To date, it is unclear if species living in warm regions, especially under the Mediterranean climate, could exhibit a diapause for a single year or enter a prolonged diapause due to higher summer temperatures experienced by eggs immediately after oviposition. In this two-year study, we tested the effect of summer temperatures on diapause of six Mediterranean tettigoniid species under natural field conditions. We found that five species can exhibit a facultative diapause depending on mean summer temperatures. For two species, a substantial shift in egg development from 50 to 90% occurred over an interval of c. 1 °C after the first summer period. All the species increased considerably their development (nearly 90%) after the second summer period irrespective of temperatures. Overall, this study suggests that diapause strategy and the different thermal sensibility of embryonic development varies considerably across species potentially affecting their population dynamics.

Two new host records for Centrodoraitalica Ferrière (Hymenoptera, Aphelinidae) from eggs of Tettigoniidae (Orthoptera, Ensifera) in northeastern Italy

The egg parasitoid Centrodoraitalica Ferrière is reported for the first time from sentinel eggs of two species of Tettigoniidae (Orthoptera), Pachytrachisgracilis (Brunner von Wattenwyl) and Eupholidopteraschmidti (Fieber). In Italy, only two hosts of this parasitic wasp are known, one of which is a tettigoniid species. Exposure of sentinel eggs represented a useful method to detect new host associations of this parasitoid species that can search for their host's eggs in the ground. The parasitoids were identified by comparing our specimens with those of the type series, and the original description of C.italica.

Illustrated key to the genera and catalogue of Mymaridae (Hymenoptera) in the Afrotropical region

Separate identification keys for females, and for males where known, of the 40 genera of Mymaridae (Hymenoptera: Chalcidoidea) in the Afrotropical region are given. The subgenera of four genera are also included in the key to females. The genera are illustrated with over 300 photographs. The 122 named, valid species reported from the region are catalogued. Reliable host records are reported for 6 genera and 11 species from rearings undertaken in the region. An appendix lists the 27 species from northern Africa and offshore islands (Canary Islands, Madeira) but not recorded in the Afrotropical region as defined in this publication. Camptoptera (Zemicamptoptera) Ogloblin Annecke, syn. n. is synonymized with Camptoptera (Camptoptera) Foerster. Eofoersteria Mathot, syn. n. is synonymized with Camptoptera Foerster and is treated as subgenus C. (Eofoersteria) Mathot, stat. n.; its type species Eofoersteria camptopteroides Mathot is transferred to Camptoptera as C. (Eofoersteria) camptopteroides (Mathot), comb. n. Polynema megacephala (Risbec) is transferred to Lymaenon as L. megacephala (Risbec), comb. n. Limacis opuntiae Risbec is transferred to Encarsia Foerster (Hymenoptera: Aphelinidae) as E. opuntiae (Risbec), comb. n. A few corrections to Huber et al. (2020) are given.

Studying genetic population structure to shed light on the demographic explosion of the rare species Barbitistes vicetinus (Orthoptera, Tettigoniidae)

Insect outbreaks usually involve important ecological and economic consequences for agriculture and forestry. The short-winged bush-cricket Barbitistes vicetinus Galvagni & Fontana, 1993 is a recently described species that was considered rare until ten years ago, when unexpected population outbreaks causing severe defoliations across forests and crops were observed in north-eastern Italy. A genetic approach was used to analyse the origin of outbreak populations. The analysis of two mitochondrial regions (Cytochrome Oxidase I and II and 12S rRNA-Control Region) of 130 samples from the two disjunct ranges (Euganean and Berici Hills) showed high values of haplotype diversity and revealed a high geographical structure among populations of the two ranges. The high genetic variability observed supports the native origin of this species. In addition, results suggest that unexpected outbreaks are not a consequence of a single or few pestiferous haplotypes but rather the source of outbreaks are local populations which have experienced an increase in each area. The recent outbreaks have probably appeared independently of the genetic haplotypes whereas environmental conditions could have affected the outbreak populations. These findings contribute to a growing understanding of the status and evolutionary history of the pest that would be useful for developing and implementing biological control strategies for example by maximizing efforts to locate native natural enemies.