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Abstract The red gum lerp psyllid, Glycaspis brimblecombei Moore, 1964 (Hemiptera: Aphalaridae), an insect pest originating in Australia and which feeds only on Eucalyptus L'Hér. (Myrtales: Myrtaceae) plants, has spread to several countries. The populations of this insect commonly reach high populations on Eucalyptus plants since its entry into Brazil, and also indicated an unrecorded behavioral. The objectives of this study were to describe a peculiar adaptation in the feeding habit of G. brimblecombei and to register the new habit. The oviposition and feeding by G. brimblecombei, commonly, on the leaves of Eucalyptus, started to occur, also, on lignified twigs. This suggests a not yet recorded adaptation of this insect to reduce insect × plant intraspecific competition. Resumo O psilídeo de concha, Glycaspis brimblecombei Moore, 1964 (Hemiptera: Aphalaridae), um inseto praga originário da Austrália e que se alimenta apenas de plantas de Eucalyptus L'Hér. (Myrtales: Myrtaceae), se espalhou por vários países. Esse inseto, geralmente, atinge grandes populações em plantas de Eucalyptus desde sua entrada no Brasil e, também, indicou um comportamento diferente. Os objetivos deste estudo foram descrever uma adaptação peculiar no hábito alimentar de G. brimblecombei e registrar o novo hábito. A oviposição e alimentação por G. brimblecombei, geralmente, nas folhas de Eucalyptus, passaram a ocorrer, também, em ramos lignificados. Isso sugere uma adaptação diferente desse inseto para reduzir a competição intraespecífica inseto × planta.

Eucalyptus species are among the most planted trees in forestry production, an ever-increasing commercial activity worldwide. Forestry expansion demands a continuous search for preventive and sanitary measures against pests and diseases. Massive application of phytosanitary products is incompatible with the forestry sector, so forest health management must be based on other principles. In this context, studies on insect plant relationships mediated by plant metabolites may contribute information relevant to plant resistance and genotype selection. In this study, we analyzed the leaf metabolome of four Eucalyptus species commonly planted in southern South America, to correlate this chemical information with feeding preference of Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), an important pest of eucalypt plantations. Gas chromatography mass spectrometry analyses were performed on polar and non-polar leaf extracts from Eucalyptus globulus, Eucalyptus grandis, Eucalyptus robusta, and Eucalyptus tereticornis (Myrtaceae). Feeding preferences were assessed in two-choice laboratory bioassays resulting in a preference gradient of the four plant species. Moreover, a performance bioassay where we contrasted survival and development time between the most and least preferred plants, showed a clear correlation with preference both in survival and developmental time of the most susceptible nymph instar. We found that species with high or low feeding preferences differ significantly in several foliar metabolites, which may be acting as feeding stimulants or deterrents for T. peregrinus. These findings may provide useful criteria for choosing Eucalyptus genotypes when planting in bronze bug infested areas.

Spondyliaspis cf. plicatuloides and Glycaspis brimblecombei (Hemiptera: Aphalaridae) are invasive insect pests of Eucalyptus, native to Australia. The insects feed on eucalypt sap, and both psyllid species exhibit clear preferences for different species and hybrids of Eucalyptus. The objective of this study was to identify the constitutive morphological and phytochemical characteristics underlying these host preferences. Four preferred and eight non-preferred eucalypt hosts were selected for evaluation. Thirteen leaf morphological features of the 12 eucalypts were analysed. The non-polar and polar metabolites in and on the surface of leaves of each eucalypt species were extracted, and their chemical composition was analysed using gas chromatography coupled with mass spectrometry. The leaf volatile profiles of hosts and non-hosts of S. cf. plicatuloides and G. brimblecombei did not differ sufficiently to explain the host choices of the two eucalypt psyllids. The leaf polar metabolite profiles of the susceptible hosts of the two psyllids differed significantly but did not explain the host preferences of the two psyllid species. However, preferred hosts of S. cf. plicatuloides and G. brimblecombei had some leaf morphological features and wax metabolites in common. Our results show that particular combinations of leaf morphological features and wax metabolites might influence the host choice of eucalypt-feeding lerp psyllids, but no traits explaining the differences in host-selection behaviour between S. cf. plicatuloides and G. brimblecombei were identified.

Insect pest invasions pose a major threat to agriculture, forestry and many natural ecosystems. Thaumastocoris peregrinus is an invasive sap-sucking pest of significant economic importance to Eucalyptus forestry that has recently invaded several countries worldwide. In this study we identify the origin and retrace the invasion history of T. peregrinus. We analysed samples from six locations in Africa, South America and Australia using microsatellites markers and a combination of clustering methods and scenario testing using Approximate Bayesian Clustering. We detected clear genetic substructure differentiating African and South American samples, with representatives of both present in Australia. The Australian population from New South Wales showed substantially higher genetic diversity than the Queensland source, which could indicate that this region could be part of the core range and evolutionary origin of the species. Africa and South America were colonised by independent introductions that occurred more or less concurrently. The study illustrates the impact of the bridgehead effect on global invasions following an outbreak or ‘invasion’ within a city in the native range of the insect.

Gonipterus species are pests of Eucalyptus plantations worldwide. The egg parasitoid wasp Anaphes nitens is used in many countries for the biological control of Gonipterus spp. Recent taxonomic studies have shown that the three invasive Gonipterus spp., which were previously considered as G. scutellatus, form part of a cryptic species complex. These taxonomic changes have implications for the biological control of Gonipterus spp. The aims of this study were to understand the species composition and distribution of Gonipterus spp. and their egg parasitoids in Australia. Gonipterus spp. adults and egg capsules were collected in south-eastern Australia and Tasmania. Adult Gonipterus were identified using morphology and DNA barcoding. Parasitoids were reared from Gonipterus egg capsules and identified. Thirteen Gonipterus species were collected: twelve species were found on the Australian mainland and one species in Tasmania. These included three described species, four previously recognized but undescribed species, two undescribed species and four unidentified species. Five egg parasitoid species that attack Gonipterus spp. were identified. Anaphes nitens, Centrodora damoni and Euderus sp. were identified on the Australian mainland and A. tasmaniae and A. inexpectatus were identified in Tasmania. The results from this study will contribute to the improvement of Gonipterus biological control in the future.

Glycaspis brimblecombei is an invasive insect species that specifically feeds on Eucalyptus leaves. Native from Australia, this species has spread to several countries becoming a major Eucalyptus pest. Even though its specific endoparasitoid Psyllaephagus bliteus has been present in Argentina since 2005, little is known about its ecology in the region. In this work we assess P. bliteus population development on Eucalypus camaldulensis and identify the meteorological variables associated with changes in its abundance. Furthermore, we study the level of natural parasitism in the field, and the density dependence relationship between P. bliteus and G. brimblecombei. We find that P. bliteus is present throughout the year with a maximum abundance at the end of spring-beginning of summer. Changes in its abundance are associated with temperature and relative humidity although it cannot be ruled out that this is due to an effect of climate on the density of its host. The highest levels of parasitism were registered when psyllid population was minimal, while density dependence analysis detected an inverse relationship between P. bliteus and its host.

Knowledge of the reproductive ecology of insect pests is important for the development of sustainable pest control strategies. Mating behavior studies can provide insights about relevant aspects of intra- or intersexual communication processes, which may lead to sustainable control strategies based on behavioral disruption. The bronze bug, Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), is an invasive eucalypt specialist that feeds and reproduces in aggregations on eucalypt leaves, causing defoliation and branch dieback in severe infestations. Scant information is available on its mating behavior, so we here report a systematic study of male–female and male-male interactions under controlled experimental conditions. Unmated, sexually mature naive males and females were paired and videotaped from two angles to describe and quantify their behavioral interactions and transitions. Intersexual interactions included mounting, rejection, copulation, antennation and a post-copulatory behavior that we termed smearing and consisted of a rapid backward and forward movement by the male while still on top female. Antennation occurred during copulation, and it may be interpreted as copulatory courtship. Smearing occurred after copulation and positively correlates with total mating time, likely involving mate guarding. Behavioral correlations with size and age showed that female rejection is not affected by male size or age. Intrasexual interactions included two agonistic behaviors that we called sparring and riding, both likely involved in male-male competition and the establishment of male dominance in natural aggregations. Male intrasexual aggressiveness was not related to male size or age either. The results are discussed in relation to the potential functions of these behaviors in the mating system of T. peregrinus.

Thaumastocoris peregrinus Carpintero and Dellapé, or bronze bug (Hemiptera: Thaumastocoridae), is a pest found in eucalyptus plantations worldwide. Use of entomopathogenic fungi has emerged recently as an alternative means of control for T. peregrinus. Here we report laboratory experiments conducted to select isolates of entomopathogenic fungi for use to control this pest. Seven isolates of Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae), 3 of Metarhizium anisopliae (Metschn.) Sorokīn (Hypocreales: Clavicipitaceae), 2 of Metarhizium robertsii J.F. Bisch., S.A. Rehner & Humber (Hypocreales: Clavicipitaceae), and 2 of Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae) at a concentration of 1 × 108 conidia per mL were assessed for their virulence to adults of T. peregrinus. In vitro growth and sporulation of the isolates also were evaluated through the analysis of colony development and conidia production in PDA culture medium, at 26 ± 1 °C, 70% RH, and a 12:12 h (L:D) photoperiod. All tested isolates were found to be pathogenic to T. peregrinus. The isolates Bb3, Bb4, Bb7, Ma1, Ma2, Mr2, and If1 exhibited significant virulence to the insect. The greatest growth (longest mean diam of colony) was for the isolate Ma2, whereas the highest sporulation rates were observed in the isolates If2 and Ma2. This study demonstrated that isolates of Beauveria, Metarhizium, and Isaria can cause infection in T. peregrinus. The Ma2 isolate of Metarhizium stood out for its pathogenic effect on the adult insect, as well as for its capacity to grow rapidly and produce large numbers of conidia on an artificial medium, indicating its potential for use as a microbial control agent for T. peregrinus, and its suitability for mass production.

Host range testing of a larval endoparasitoid Eadya daenerys Ridenbaugh (Hymenoptera: Braconidae) was conducted. Eadya daenerys is most commonly associated with Paropsisterna agricola (Chapuis) in Australia, but is proposed as a biological control agent for Paropsis charybdis Stål (Coleoptera: Chrysomelidae) in New Zealand. Nine species of non-target beetles with spring-active, external leaf-feeding larvae, were host tested. Development to emergence only occurred within eucalypt-feeding Paropsina pests: the target P. charybdis and another pest Trachymela sloanei (Blackburn). Unsuccessful internal parasitism occurred in four less closely related non-target Chrysomelinae. Considering the different feeding niches occupied by these beetles, we hypothesize that Eadya daenerys is unlikely to cause direct non-target impacts beyond pest Paropsina species in the New Zealand environment.

In the last 10 years, four species of psyllid were detected in Brazil on eucalypts: Ctenarytaina spatulata in 1994, Blastopsylla occidentalis in 1997, Ctenarytaina eucalypti in 1998 and Glycaspis brimblecombei in 2003. The latter two are serious pests in several countries. In Brazil, G. brimblecombei caused significant damage to the eucalypt plantations in the first years of its introduction. Now this pest is under control due to the programmes of integrated pest management, where the parasitoid is the principal control agent. The four eucalypt psyllid species introduced into Brazil are presented with information on distribution, hosts, biology and control.