Austral Entomology最新文献

Diamides are an important class of insecticides for control of insect pests in Australian farming systems. Their favourable toxicological and environmental profiles have led to broad registration across multiple pest species and crop types. However, widespread use is known to compromise insecticidal efficacy due to resistance, and concerns have been raised about the sustainability of these insecticides in Australian agriculture, particularly since the incursion of Spodoptera frugiperda in 2020. As a first step in pre-emptive management of S. frugiperda, baseline susceptibility to cyantraniliprole was determined in larval bioassays performed on 16 field populations collected from maize and sweet corn between 2020 and 2021 during the initial period of establishment in Australia. There was a narrow (2.1-fold) range of intra-specific variation in cyantraniliprole susceptibility amongst field populations. The average median lethal concentration was 0.088 mg L⁻¹, which was significantly higher than in Helicoverpa armigera (LC₅₀ = 0.037 mg L⁻¹). An analysis of relative diamide toxicity showed that while the median concentration of chlorantraniliprole was significantly higher than cyantraniliprole in S. frugiperda, there was no significant difference between the toxicity of chlorantraniliprole and cyantraniliprole at the LC_99.9 level. Using the dose–response data generated from these bioassays and taking into account empirical survival, a concentration of 2 mg L⁻¹ of cyantraniliprole was determined to be a suitable dose for discriminating between cyantraniliprole-susceptible and cyantraniliprole-insensitive phenotypes of S. frugiperda.

For about the past 120 years, Apiomorpha crispa (Fuller, 1896) has been considered to be a junior synonym of A. strombylosa (Tepper, 1893). Although some morphological variation among specimens of A. strombylosa has been recognised across its range, geographic separation and different host associations led to coccidologists treating the variation as belonging to two forms rather than there being distinct species. Here, we use allozyme electrophoresis and DNA sequencing of mitochondrial and nuclear genes to test the hypothesis that A. strombylosa, as currently treated, is a single biological species. We find that the ‘eastern’ and ‘western’ forms of A. strombylosa sens. lat. are distinct species with no evidence of recent gene flow despite both forms sometimes being in close geographic proximity. The two species are morphologically distinct and induce galls on different Sections of Eucalyptus L'Herit. We hereby resurrect Brachyscelis (=Apiomorpha) crispa (Fuller, 1896) reinst. stat. from synonymy with Brachyscelis (=Apiomorpha) strombylosa (Tepper, 1893) and provide a revised description of the species.

A new assassin bug species in the genus Rasahus Amyot & Serville, 1843, R. ellipticus sp. nov., is described based on specimens from Mexico and Argentina. Morphological comparations between the new species and its related species, R. biguttatus (Say, 1832) and R. hamatus (Fabricius, 1781) are provided together with illustrations of habitus and male genitalia of all three species. Rasahus bifurcatus Champion, 1899 was described initially based on submacropterous specimens, and the macropterous male of this species is reported for the first time in the present study. Rasahus sipolisii Fallou, 1887 reinst. stat., which was synonymized with R. hamatus by Bergroth in 1892, is confirmed to be a valid species, and R. angulatus Coscarón, 1986 syn. nov. should be treated as its junior synonym. Lectotypes of Lestomerus varipes Fallou, 1891, Pirates concisus Walker, 1873, R. bifurcatus Champion, 1899 and R. sipolisii Fallou, 1887 are designated.

The large genus Campylocheta Rondani, 1859, comprising 48 species, occurs in all major biogeographical regions of the world, except Antarctica. Homohypochaeta Townsend, 1927 and Hypochaetopsis Townsend, 1915 are two Neotropical genera similar to Campylocheta, with only two and one species respectively. No additional information is known about these genera apart from their original descriptions. These two poorly known genera are herein treated as junior synonyms of Campylocheta based on the study of the holotypes of the type species and additional specimens from Ecuador. This research produced the following new combinations: Campylocheta reclinata (Townsend, 1927) comb. nov., Campylocheta ucayali (Townsend, 1929) comb. nov., and Campylocheta chaetosa (Townsend, 1915) comb. nov. Moreover, the following three new species are described: one from Ecuador, Campylocheta auripilosa sp. nov., and two from Brazil, C. papaveroi sp. nov. and C. memphisphaga sp. nov. In addition, a new host record of the genus Campylocheta is reported from the Neotropical Region. Illustrations and detailed descriptions and redescriptions are provided for C. reclinata, C. chaetosa, C. auripilosa sp. nov., C. papaveroi sp. nov and C. memphisphaga sp. nov. The male and female terminalia of C. reclinata comb. nov. are also described for the first time. Finally, an identification key is provided for the Neotropical Campylochetini genera and all Campylocheta species that occur in the Neotropical Region.

Island ecosystems offer unique opportunities to study the dynamics of species that rely on ephemeral resources such as carrion. This study investigated the necrophagous insect communities associated with carrion of silver gulls (Chroicocephalus novaehollandiae) on a small nearshore island off the east coast of Australia, to assess how necrophagous insect communities on islands compare with the mainland community, and the degree to which these communities varied over time. Over three breeding seasons, we analysed what insect species were colonising gull carcasses and, using baited traps, compared total adult community composition and richness of carrion-associated insect species on the island with the adjacent mainland. Our findings reveal that an island separated by less than 500 m from the mainland can harbour distinct carrion-breeding fly assemblages. These assemblages vary between years but are notably dominated by a potential seabird-carrion specialist fly—the littoral species Calliphora maritima. These results underscore the importance of seabird carrion as a critical resource for necrophagous insects on islands and contribute to our understanding of how island environments influence insect community dynamics and specialisation.

In most tropical and subtropical regions of the Americas, the corn leafhopper, Dalbulus maidis (DeLong & Wolcott)(Hemiptera: Cicadellidae), is a significant pest of corn. Crop losses occur not only due to direct damage from feeding and oviposition but also because this leafhopper is vector of various pathogens causing important outbreaks of the corn stunt disease. While parasitoids are the better-studied natural enemies of this leafhopper, its predators remain largely unknown. This study records, for the first time, 26 predator species [14 spiders, three lacewings (Chrysopidae), two assassin bugs (Reduviidae), one big-eyed bug (Geocoridae), one hoverfly (Syrphidae), four ladybugs (Coccinellidae) and two pincer wasps (Dryinidae)] as active predators of the vector in cornfields of northern Argentina. These records, along with the three previously known species, form a complex of 29 species preying on different stages of the vector in Argentina. With this contribution, 40 species of predators are now documented across the Americas, providing a valuable natural resource that should be conserved.

No abstract is available for this article.

This study is focused on the parasitic wasps Heimbra Cameron, 1909 (Heimbrinae), a small and poorly represented genus in entomological collections. Herein, two new species are described: Heimbra dioneae sp. nov. and Heimbra pulchra sp. nov., both from Brazil, and a new geographical record to Heimbra bicolor Subba Rao, 1978 is reported. Additionally, we provide maps with the geographical distribution of the studied species based on the new records and literature data, and an identification key for the known species of Heimbra.

Oviposition and agonistic behaviour are important traits for understanding the pattern of coexistence and choice of host fruit shared between natives and invasive species. This study aimed to evaluate the interspecific interactions and the choice of the oviposition sites among three native species of fruit flies of the genus Anastrepha: Anastrepha obliqua (Macquart), Anastrepha fraterculus (Wiedemann), Anastrepha sororcula Zucchi, and an invasive species, Ceratitis capitata (Wiedemann). The interactions between species were measured by counting the number of eggs laid in semi-ripe and ripe guavas (Psidium guajava L.) in intra and interspecific combinations. Additionally, we compared the absolute frequency of agonistic behaviours in interactions between native and invasive fruit flies. The native species of Anastrepha did not change their preference for the fruit ripening stage, even in face of the invader C. capitata. Anastrepha species and C. capitata preferred to oviposit in semi-ripe fruits, in all experimental scenarios. We also observed that C. capitata avoided interactions with the native species by preferring to oviposit in ripe fruits when in the presence of Anastrepha species. All species reduced the number of laid eggs when in the presence of heterospecific females. Aggression was the most frequent agonistic behaviour in all species combinations, followed by display/stalking and avoidance. Finally, our results showed that aggression behaviour was the most frequent in interactions of Anastrepha species with C. capitata.

The fall armyworm, Spodoptera frugiperda, is a highly polyphagous pest, native to the tropical and subtropical regions of the Americas that invaded the Australian mainland in 2020. Since its incursion into Australia, management has largely relied on the use of different synthetic insecticides. Given pesticide resistance genes and reduced sensitivities to a variety of pesticides are already present in the population, there is a need to investigate alternative management approaches that can be incorporated into an IPM programme such as biological control. A fundamental step in establishing the potential of biological control is identifying the potential natural enemies that may be deployed in pest management. In this study, we undertook a series of surveys to identify potential parasitoids for fall armyworm and assessed parasitism rates in Western Australia (WA) and the Northern Territory (NT). Approximately, 1900 larvae of fall armyworm were sourced from maize, sweet corn, okra and sorghum fields, reared and observed for the emergence of parasitoids. Ten species of larval parasitoids from five families were recorded during the surveys with Cotesia ruficrus (Haliday) (56.14%) and Exorista xanthaspis (Wiedemann) (50%) being the most abundant larval species in WA and NT, respectively. Other parasitoids found include four recently described species, Euplectrus frugiperdata Fagan-Jeffries, Chelonus trojanus Fagan-Jeffries, Coccygidium necatrix Atkin-Zaldivar & Fagan-Jeffries, Coccygidium mellosiheroine Atkin-Zaldivar & Fagan-Jeffries, and previously named species, Megaselia scalaris (Loew) and some unidentified Tachinidae. Two species of egg parasitoids, Trichogramma pretiosum (Riley) and Telenomus remus (Nixon), were recovered with field parasitism rates of 7.81% and 10.16%, respectively. Overall, the occurrence of potential egg and larval parasitoids in Australian horticulture systems provides a unique platform to develop a conservation or augmentative biological control approach to manage fall armyworm in Australia.