The yellow mealworm, Tenebrio molitor (L.) (Coleoptera: Tenebrionidae), is a significant stored-product pest, a valuable insect for animal feed production and a study system for immunology and entomopathogens, including entomopathogenic nematodes (EPNs). However, the efficacy and biocontrol potential of Australian EPN isolates against this host remain unexplored. We evaluated the virulence, establishment rate and reproductive potential of 17 Australian EPN isolates of Heterorhabditis and Steinernema in T. molitor larvae under laboratory conditions. All isolates successfully infected, killed and reproduced within T. molitor larvae, although their performance varied markedly. Heterorhabditis indica Hi.LMBT, Hi.LMI2 and Hi.HRN2 emerged as the most virulent isolates. EPN establishment rate in the host differed strongly among isolates, ranging from 5.8 to 17.2%, with Steinernema feltiae Sf.ECCS and Heterorhabditis marelatus Hm.ENCB showing the greatest establishment rate in the host. Reproductive potential ranged from ∼56,000 to ∼140,000 IJs per larva, with S. feltiae Sf.Y13 and Heterorhabditis zealandica Hz.NAR4 showing the highest reproduction. Multivariate and correlation analyses indicated substantial within-species variation for EPN species represented by multiple isolates, and that virulence, establishment rate and reproductive potential in T. molitor were not correlated with each other among isolates. Our results highlight considerable potential of Australian EPN isolates for mealworm control, while showing that candidate selection should not rely on virulence alone. Instead, effective screening should integrate virulence, establishment rate and reproductive potential to identify promising isolates that warrant further evaluation under realistic stored-product conditions.

Several insect lineages, including some fruit flies, have evolved mutualistic associations with primary symbiotic bacteria. Some species of Tephritinae, the most specialized subfamily of fruit flies (Diptera, Tephritidae) harbour co-evolved, vertically transmitted and non-culturable bacterial symbionts in their midgut, known as Candidatus Stammerula spp. (Enterobacteriaceae). While such associations have previously been reported in the Palearctic and Hawaiian Archipelago, their occurrence in Australasia had not been investigated. In this study we assessed the genetic diversity of eight Australian fruit fly’s species from six genera belonging to the Tephritini tribe using mitochondrial markers (16 S rRNA and COI–tRNALeu–COII genes) and compared their bacterial diversity using the 16 S rRNA gene. We detected the presence of specific symbiotic bacteria in all sampled species. Analysis of bacterial 16 S rRNA showed that, with one exception, all Australian symbionts clustered in a well-supported monophyletic clade with Ca. Stammerula detected in Palearctic and Hawaiian Tephritini. Distinct Stammerula lineages were identified in several taxa, while two species, Trupanea prolata and Spathulina acroleuca shared identical symbiont sequences and the same host plant. Notably, Australian and Palearctic Sphenella spp. harboured closely related symbionts. The cophylogenetic analysis revealed a substantial congruence between host and symbiont tree, supporting a history of cospeciation and suggesting biogeographic links between Australasian and Palearctic taxa. Overall, the results expand the geographic knowledge of Tephritini-Ca. Stammerula association and highlight a global pattern of co-diversification.

Gut microbiomes are fundamental to animal biology, evolution and health. True bugs (Hemiptera) maintain heritable microbial gut symbionts and are research models for host-microbe interactions. However, current knowledge is mostly limited to the bacterial symbionts in the Holarctic-Oriental bug fauna, leaving the microbial symbioses of the Australasian diversity unknown. Using high-throughput amplicon sequencing, we characterized the bacterial and fungal communities of four Australian stink bug species associated with citrus: Biprorulus bibax , Poecilometis strigatus (Pentatomidae), Lyramorpha rosea and Musgraveia sulciventris (Tessaratomidae). Across all species, bacterial communities were low in diversity, with each species harbouring a dominant and distinct gammaproteobacterial symbiont within the Pantoea-Erwinia complex. However, L. rosea and P. strigatus contained more diverse assemblages including low-abundance secondary taxa. Furthermore, each host species harboured a differentiated fungal consortium that was diverse across hosts and dominated by taxa including Cladosporium , Eremothecium and Malassezia . Although the dominant bacterial symbionts were host-specific, their phylogeny was incongruent with the host phylogeny, probably indicating host switches and decoupled host-symbiont evolutionary histories. We also found evidence that in B. bibax , the Pantoea -like symbiont was vertically transmitted via egg smearing. Egg surface sterilisation resulted in aposymbiotic offspring with delayed development, reduced longevity and lower fecundity, demonstrating a symbiont contribution to host fitness. Overall, our findings of the first comparative gut microbiome analysis of Australian stink bugs support globally conserved association patterns with Pantoea -like symbionts alongside species-specific microbial community structure and advanced the understanding of host-microbe evolution in these insects.

BACKGROUND:Maternally transmitted endosymbionts like Wolbachia and Cardinium are common in arthropods including many pest species. By inducing cytoplasmic incompatibility (CI), they can support sustainable pest management via population-suppression or replacement strategies. However, models underlying these approaches often neglect female remating and the pre- and post-copulatory mechanisms that influence sperm use and compatibility. In many species, females mate multiple times and may encounter both compatible and incompatible males, potentially altering CI expression and endosymbiont spread. We therefore tested how remating and mating order affect CI and reproductive fitness in Kelly's citrus thrips, Pezothrips kellyanus, a haplodiploid citrus pest naturally carrying either Cardinium alone (C) or both Cardinium and Wolbachia (CW). RESULTS:We found that CI depended strongly on mating history. When a C female first mated with an incompatible CW male, CI was strong, and a second mating with a compatible C male only restored approximately 21% of female offspring production. Conversely, when a C female first mated with a compatible C male and then with an incompatible CW male, CI was substantially weaker, consistent with first-male sperm precedence. Female fitness also varied with mating history; C females mated twice with CW males had the lowest fecundity, highest embryonic and post-embryonic mortality, and shortest survival. CONCLUSION:First-male sperm precedence limits restoration of female offspring production by a compatible mating following an incompatible mating. This may increase the fitness costs of accepting incompatible males in hosts with pre-copulatory mate discrimination. More broadly, remating and mate sequence can alter CI strength, affecting models of endosymbiont spread and endosymbiont-based pest management. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

ABSTRACT The small hive beetle (SHB; Aethina tumida ) is a major pest of honey bees that has threatened Australia's apiculture industry since its detection in 2002. Worryingly, the impact of SHB may be exacerbated by the recent establishment of Varroa destructor in eastern Australia. Soil‐borne entomopathogenic nematodes (EPNs) are promising biocontrol agents against SHB because this pest pupates in the soil near honey bee colonies. Previous semi‐field and field studies have evaluated EPN efficacy against soil‐dwelling SHB stages without distinguishing their effects on pupae from those on wandering larvae. Therefore, it remains unknown whether Australian EPN isolates are effective when applied after SHB has entered the soil and begun pupation. Yet, SHB pupae are immobile within an enclosed pupation chamber in the soil and may have lower EPN susceptibility and encounter rates than wandering larvae. Here, we tested two Australian EPN isolates, Heterorhabditis indica Hi.HRN2 and Steinernema carpocapsae Sc.EG, against SHB pupae in natural soil under glasshouse conditions. Both isolates performed similarly and were highly effective, causing more than 60% mortality before adult emergence, compared with approximately 12% mortality in untreated controls. Their effects persisted after emergence: among emerged adults, 38%–41% died within 7 days post‐emergence in the EPN treatments, compared with approximately 2.5% in controls. Total mortality reached approximately 77% for both EPN isolates, compared with 14% in controls. These findings highlight the substantial potential for EPN soil applications to reduce SHB pest pressure outside honey bee hives even when SHB have already pupated and provide a foundation for future field studies.

Insects are associated with diverse RNA viruses, including vertically transmitted viruses that form persistent infections without apparent symptoms. One of the first documented vertically transmitted viruses is a sigmavirus (Rhabdoviridae) affecting fitness of Drosophila. Sigmaviruses and related rhabdoviruses have also been detected in pest fruit flies and other arthropods. However, their prevalence, transmission, tissue localisation and fitness effects remain poorly known, despite their potentially common infections in diverse hosts. We investigated Sigmavirus tryoni (BtSV) prevalence, load, transmission across multiple generations and host effects in Queensland fruit fly (Bactrocera tryoni), Australia’s most significant horticultural pest, which carries BtSV at low prevalence (13.7%) across field populations. We detected BtSV in 6 of 12 laboratory populations (at a prevalence of 12.5% to 80.4%) where it was transmitted biparentally within embryos. Although incomplete, maternal transmission was more reliable and resulted in higher BtSV load than paternal transmission. Paternally transmitted BtSV was almost entirely lost after two generations. BtSV became detectable in most uninfected individuals cohabiting with infected flies, but this resulted in a low load that was subsequently transmitted to only few offspring. BtSV occurred across developmental stages, digestive and reproductive tissues, albeit its viral load was lower in reproductive tissues when received paternally than maternally, and lower in testes than ovaries. Furthermore, BtSV-infected individuals suffered paralysis and mortality when exposed to high CO2 concentrations at low temperature, a Rhabdoviridae effect previously reported for Drosophila species, a muscid fly and mosquitoes. Our study suggests that sigmavirus transmission dynamics and fitness effects may apply broadly to arthropod hosts and affect their management.

Mites of the family Podapolipidae (Heterostigmata: Acariformes) are among the most morphologically diverse parasitic arthropods, exhibiting extreme specialisation associated with insect hosts from several orders. Current records substantially underestimate their host range; despite high diversity on Coleoptera, these mites are recorded from only a handful of terrestrial beetle families. Here, we describe a remarkable new genus and species, Hydrophilopolipus hajiqanbari gen. nov., sp. nov., from the hydrophilid beetle Coelostoma fabricii (Montrouzier) in Australia, expanding podapolipid host lineages to include semi-aquatic beetles. The new genus exhibits numerous apomorphic features, several of which appear to be unique within Podapolipidae, most strikingly in males, which show a drastic reduction of the gnathosoma and complete loss of the chelicerae. Moreover, in all life stages, idiosomal setae v1 and 3a are reduced to alveoli, setae c1 are absent, and the tibial solenidion (φ) on leg I is lacking. Males also lack plate EF and setae f, and larvae have separate plates C, D, and EF but lack plate H and setae h2. Despite these reductions, we argue a sister-group relationship with the carabid-associated genus Eutarsopolipus, the only other podapolipid genus with both hexapod females and hexapod males bearing terminal genitalia. We discuss the evolution of “headless” males, and other reductive features, in the context developmental progenesis, suggesting that similar evolutionary trajectories may be more widespread within Podapolipidae and other parasitic mites than currently recognised, particularly among lineages associated with poorly explored non-terrestrial hosts.

Blow flies can be used as alternative pollinators to honeybees for several crops. However, they can potentially vector harmful bacteria to surfaces on which they land. Therefore, there is a risk that blow flies may contaminate flowers, and thereby fruit, with human pathogens. Growers, supermarkets and consumers may therefore have concerns about food safety. To address these concerns, we asked: (1) do fly visits result in altered bacterial communities on flowers, and if so, (2) do these altered communities persist to the fruit stage? We exposed strawberry flowers to “clean” blow flies and flies that had contacted a common environmental contaminant (cow manure). Using a 16 S rRNA gene amplicon sequencing approach, we evaluated the impact of the blow fly visits on the flower and fruit microbiomes. We found that the fruit microbiome was not impacted by our treatments, specifically, no shared amplicon sequence variants were found in both the manure and the resulting fruit that developed after pollination by a manure-exposed fly. This suggests that fly pollination is unlikely to pose a risk to human health. Our study may help to alleviate concerns from growers and consumers of using flies as managed pollinators in the agrifood system.

RNA viruses are common in tephritid fruit flies including the Queensland fruit fly, Australia’s most significant horticultural pest. For many their transmission, tissue tropism and load across host development remain unexplored. Yet these factors are important for host biology, ecology and pest management. We investigated Bactrocera tryoni orbivirus (OV), Bactrocera tryoni xinmovirus (XV), Bactrocera tryoni toti-like virus (TLV) and Bactrocera tryoni iflavirus species 2 (IVsp.2) that commonly coinfect B. tryoni laboratory populations. OV and XV transmission was vertical within and on eggs, while TLV transmission was vertical within eggs. IVsp.2 was not detected in eggs but was present in adults; however, IVsp.2 was horizontally transmitted, with viral load increasing with cohabitation time with infected flies. Horizontal transmission was not observed for the other viruses. OV had a similar load across all tissues, while XV was consistently more abundant in ovaries. TLV had a high viral load in the brain whereas IVsp.2 was abundant in the thorax, foregut and midgut. Besides differences in eggs, the viruses were detected in all other developmental stages, but viral load patterns differed: viral load remained constant for TLV, fluctuated for OV and XV, and was low in pre-adult stages and high in adults for IVsp.2. Our findings demonstrate distinct transmission strategies and tissue tropism among the viruses, providing new insights into their epidemiology and role in host biology. Furthermore, contrary to prevailing views that viruses are generally horizontally transmitted, most known RNA viruses of B. tryoni are vertically transmitted affecting the evolution of host-virus interactions.

BACKGROUND:Pest fruit flies commonly carry diverse RNA viruses with unknown host effects that may affect pest management strategies. We investigated effects of horizontally transmitted cripavirus and vertically transmitted iflavirus in Queensland fruit fly that also carried orbivirus, toti-like virus and xinmovirus as persistent covert infections. RESULTS:Individuals persistently infected with these five viruses had slower egg-to-pupa development, lower emergence and lower adult survival under stress than individuals without cripavirus and iflavirus, but persistently infected with the other three viruses. Pupal weight and flight ability did not differ. Cripavirus and iflavirus loads were stable, even under stress, except for the iflavirus load which was higher in flies that died late and lower in flies under stress after cold treatment. Injection into flies of a suspension containing all five viruses caused high mortality within 20 days irrespective of a persistent iflavirus infection. This resulted in an increased iflavirus load 2 days after injection, whereas the load of the other four viruses did not change, suggesting that iflavirus may have caused the mortality. By contrast, feeding the mixed virus suspension did not reduce survival. Although iflavirus was detected immediately after ingestion, its load decreased over 14 days as expected for a maternally transmitted virus. The load of the other four viruses remained unchanged. CONCLUSION:RNA viruses can affect control strategies involving mass-reared flies such as the sterile insect technique in different ways. Persistent virus infections may moderately influence fly fitness, whereas newly acquired infections may result in increased virus replication and fly mortality. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Entomopathogenic nematodes (EPNs) are effective biocontrol agents against soil-borne insect pests, yet the risks they pose to beneficial insects are understudied, particularly when applied outside soil environments. With growing interest in above-ground applications of EPNs such as on crop foliage or against pests of the western honey bee (Apis mellifera) in hives, it is essential to evaluate their effects on honey bees. We conducted a large-scale assessment of honey bee brood and adult worker susceptibility to Australian EPN isolates ex situ and in situ. At 25 °C, filter paper bioassays showed that larvae (final instar) were highly susceptible to all EPN isolates (LC50 range: 0.66 to 6.8 IJs/cm2), with Heterorhabditis indica (particularly isolates Hi.HRN and Hi.HRN2) being the most virulent. Increasing the assay temperature to 33 °C slightly reduced virulence across isolates, yet all remained pathogenic (LC50 range: 0.7 to 9 IJs/cm2). Similarly, adult workers were highly susceptible (LC50 range: 1.8 to 10 IJs/cm2), again with H. indica Hi.HRN2 showing the greatest virulence. Conversely, Steinernema feltiae (notably isolate Sf.CPBR2) was the least virulent species, although it was still capable of causing high mortality in both honey bee larvae and workers. Interestingly, parasitisation of honey bee larvae by Varroa destructor increased susceptibility to S. feltiae Sf.CPBR2 but not to H. indica Hi.HRN2. Under hive-like conditions, direct treatment of uncapped and capped brood cells with H. indica Hi.HRN2 resulted in <50 % larval and <33 % pupal mortality. Finally, H. indica Hi.HRN2 treatment of subcolonies caused 19 % larval, 5.5 % pupal and 18 % adult worker mortality. Overall, our results indicate that EPN above-ground applications require precautions to safeguard honey bees, particularly during honey bee foraging or for in-hive use.

Eusociality in insects has arisen multiple times independently in Hymenoptera (bees, wasps and ants), Blattodea (termites) and Coleoptera (beetles). In Hymenoptera and Blattodea, the evolution of eusociality led to species proliferation. In the hyperdiverse Coleoptera, obligate eusociality evolved only once, in the ancient Australian ambrosia beetle Austroplatypus incompertus (Curculionidae: Platypodinae). This species occurs patchily in mesic eucalypt forests of eastern Australia, from Victoria to northern New South Wales, and has a low dispersal capacity. Based on individuals collected from the southern and northern edges of its distribution, it was initially described as two distinct species. However, the names were later synonymised as no morphological differences were found throughout the species' distribution. Recent mitochondrial analyses revealed substantial latitudinal divergence across populations. To address this disparity between morphological and molecular data, we sequenced and analysed a SNP panel of over 6656 biallelic markers from 187 individuals from 11 sites across 1000 km of this species' range. Our data indicate that eusocial demographic processes such as limited dispersal and reliance on few reproductive individuals, together with habitat fragmentation, contributed to the genetic structuring of this species into northern, central and southern lineages. We further identified low levels of introgression between the highly diverged central and northern lineages at a site close to the Hunter Valley biogeographic barrier, possibly due to secondary contact. Our results highlight the interplay of biogeography and life history on the genomic divergence in this unique ambrosia beetle lineage of important standing in the evolution of eusociality in insects.

Maternally transmitted endosymbionts of arthropods are common and phylogenetically diverse. Several bacteria, including Wolbachia and Cardinium, have independently evolved the ability to induce cytoplasmic incompatibility (CI) limiting the reproduction in females lacking the endosymbionts carried by their mates. While promoting endosymbiont spread, CI is costly to endosymbiont-free females. Such host-endosymbiont conflicts are expected to affect host mating preferences, yet this has scarcely been studied in hosts carrying multiple, potentially competing, endosymbionts. We investigated mate choice and chemical communication in a significant pest of citrus, Kelly's citrus thrips (Pezothrips kellyanus), naturally carrying CI-inducing Cardinium and Wolbachia. Unlike females with both endosymbionts (CW) that had no preference for males with particular endosymbiont associations, females with only Cardinium (C) preferred compatible C and endosymbiont-free males over incompatible CW males. In contrast, endosymbiont-free females showed no preference, despite experiencing similar CI risks when facing incompatible C and CW males. Male mating success, however, mostly depended on female receptivity and not on endosymbiont association. Furthermore, chemical analyses revealed that males with different endosymbiont associations had distinctly different cuticular hydrocarbon (CHC) profiles, with the CHC profile of CW males markedly including tridecane, a compound known to influence animal behavior. The results indicate that Cardinium enables females to avoid Wolbachia-induced CI based on the distinct chemical cues of incompatible males. Our findings highlight the role of common endosymbionts and their interactions in sexual selection through their effects on chemical and behavioral traits of hosts, emphasizing the importance of these factors in endosymbiont and host population dynamics, as well as endosymbiont-based pest control strategies.

BACKGROUND:The small hive beetle (SHB; Aethina tumida) is a significant pest affecting honey bees and the global beekeeping industry. The harmful effects of chemical pesticides on bee health, non-target species and ecosystems highlight the need for sustainable SHB control methods. Soil applications of entomopathogenic nematodes (EPNs) targeting the soil-dwelling life stages (wandering larvae, pupae and emerging adults) of SHB present a promising biological control approach. We conducted comprehensive laboratory experiments to evaluate the biocontrol potential of 32 Australian isolates of five EPN species (Heterorhabditis bacteriophora, Heterorhabditis indica, Heterorhabditis zealandica, Steinernema carpocapsae and Steinernema feltiae) against SHB. We also performed a glasshouse experiment testing the efficacy of nine EPN isolates in soil mesocosms that simulated field conditions. RESULTS:We demonstrated that all isolates caused mortality in all life stages, with wandering larvae the most susceptible, followed by pupae and adults. Notably, H. indica Hi.HRN caused the highest SHB mortality, while S. feltiae Sf.EG was the least effective. These isolates significantly reduced SHB adult emergence, ranging from 9%-93% in autoclaved sterile soil and 16%-59% in natural soil, suggesting interaction with other soil biota. The isolates H. indica Hi.HRN, Hi.LMBT and H. bacteriophora Hb.HIE2 were the most promising candidates for biocontrol, causing >90% corrected SHB mortality in sterile soil and >80% in natural soil. Additionally, soil application of Hi.HRN caused 33% and 43% mortality of SHB adults after their emergence from natural and sterile soils. CONCLUSION:The H. indica isolates Hi.HRN and Hi.LMBT displayed strong biocontrol potential, warranting further evaluation. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Xanthomonas citri comprises phytopathogenic pathovars that can cause disease in mangoes and cashews. X. citri pv. mangiferaeindicae (Xcm) causes mango bacterial black spot and X. citri pv. anacardii (Xca) causes cashew bacterial black spot. Currently, there are a limited number of complete genomes available for these pathovars, hindering pathogenicity studies. Here, we collected 53 isolates of Xcm and Xca from mango hosts and generated 50 Xcm (18 complete and 32 scaffold level) and three complete non-pigmented Xca genome assemblies using Illumina and Nanopore sequencing. We used comparative genomics to identify virulence-associated genes of both pathovars and found that transcription activator-like effectors (TALEs), which aid in host-plant infection, were present in complete and circularised assemblies of Xcm. One to three plasmids were identified amongst the complete Xcm assemblies, while no plasmids were observed in Xca. Analysis of complete and circularised genomes revealed the presence of 14 TALE classes either in chromosome or plasmid positions. Amongst them, only the TalKC class was shared across all strains. Although no plasmid was found in Xca, the TalKS class genes were found in the bacterial chromosome. Virulence-associated genes varied at the interspecies level, with Xca and Xcm shown to have distinct sets of type III effectors. We observed that xopB, xopAG2 and xopAM were present in all Xca strains but absent in Xcm. In contrast, xopAW was present in all Xcm but absent in Xca. Further functional investigation of these genes could reveal those that play a critical role in pathogenicity and/or host specificity.

Western honey bee (Apis mellifera) faces substantial threats from pests such as small hive beetle (SHB; Aethina tumida), greater wax moth (GWM; Galleria mellonella) and lesser wax moth (LWM; Achroia grisella). Entomopathogenic nematodes (EPNs) could serve as promising biocontrol agents to manage these pests; however, their efficacy can vary with target pest species with different body mass and life cycles, EPN species and isolates, and concentrations applied. Although numerous EPN studies have been performed on GWM and some on SHB, very few have been conducted on LWM, and none have directly compared EPN performance across these three pests. Here, we evaluated and compared the virulence, penetration rates and reproductive potential of 15 Australian isolates of five EPN species against body mass-standardised larvae of SHB, GWM and LWM. We found that SHB consistently experienced the lowest and slowest mortality across all EPNs, while GWM consistently experienced the highest and fastest mortality. Notably, Heterorhabditis indica Hi.HRN2 and Hi.HIE2 were among the most virulent isolates in SHB and GWM, whereas Heterorhabditis bacteriophora Hb.EG was the most virulent EPN isolate in LWM. Additionally, EPN isolates exhibited on average 5 × lower penetration rates and 1.5 × lower reproductive success in SHB compared to GWM and LWM. Our study found significant variation in EPN efficacy across the three honey bee pests and provides the basis for the selection of effective isolates and concentrations for targeted biological control of honey bee pests, though the evaluation of EPN safety for honey bee will also be essential.

The capacity for terrestrial ecosystems to sequester additional carbon (C) with rising CO2 concentrations depends on soil nutrient availability1,2. Previous evidence suggested that mature forests growing on phosphorus (P)-deprived soils had limited capacity to sequester extra biomass under elevated CO2 (refs. 3-6), but uncertainty about ecosystem P cycling and its CO2 response represents a crucial bottleneck for mechanistic prediction of the land C sink under climate change7. Here, by compiling the first comprehensive P budget for a P-limited mature forest exposed to elevated CO2, we show a high likelihood that P captured by soil microorganisms constrains ecosystem P recycling and availability for plant uptake. Trees used P efficiently, but microbial pre-emption of mineralized soil P seemed to limit the capacity of trees for increased P uptake and assimilation under elevated CO2 and, therefore, their capacity to sequester extra C. Plant strategies to stimulate microbial P cycling and plant P uptake, such as increasing rhizosphere C release to soil, will probably be necessary for P-limited forests to increase C capture into new biomass. Our results identify the key mechanisms by which P availability limits CO2 fertilization of tree growth and will guide the development of Earth system models to predict future long-term C storage.

Many arthropods carry maternally inherited endosymbionts that cause cytoplasmic incompatibility (CI), manifested as embryonic mortality in matings of infected males with uninfected females. Infected females, however, do not suffer this cost. Therefore, in populations with mixed endosymbiont infections, selection is expected to favour mechanisms that enable hosts to avoid or mitigate CI. This may include changes in mating behaviour, such as reduced female receptivity to mating and/or remating when approached by incompatible males. Here, we investigated mating behavioural traits in haplodiploid thrips naturally associated with two CI-inducing endosymbionts, Cardinium and Wolbachia . Compared with females with both endosymbionts, those with only Cardinium showed reduced receptivity to males carrying both. However, surprisingly, females without endosymbionts were not less receptive to incompatible males. Furthermore, in contrast to females without endosymbionts, females with Cardinium were far less likely to remate with incompatible than compatible males irrespective of the compatibility type of the first mating. Our results suggest that endosymbiont-specific sexual selection processes occur, whereby females carrying only Cardinium recognize Wolbachia in coinfected males to avoid CI. This may hinder a CI-driven Wolbachia spread. Endosymbiont-mediated mating behaviours may be crucial for the dynamics of CI-inducing endosymbionts and their application in pest management strategies.

BACKGROUND: Many studies have demonstrated that tephritid fruitfly larvae are highly susceptible to entomopathogenicnematodes (EPNs) and may become infected as they enter the soil to pupate. However, the susceptibility of adult tephritidsand their suitability as EPN targets have been less studied. We performed laboratory assays with 12 Australian EPN strains ofHeterorhabditis bacteriophora,Heterorhabditis indicaandHeterorhabditis zealandicain adults of the Queensland fruitfly,Bac-trocera tryoni. Infective juveniles were delivered in a yeast hydrolysate solution that is attractive toflies. We also measuredtheflight ability of adults up to 3 days after treatment. RESULT: Flies that consumed the EPN-yeast preparation experienced 72.8-84% mortality. Between 33.5% and 46.2% of EPN-treated adults were still able tofly before death following treatment, mostly within thefirst day, thereby contributing toEPN dispersal. Another 31.9-39.9% of EPN-treatedflies that were unable tofly died as a result of EPN treatment. Overall,>65% offlies that died following EPN treatment had visible signs of infection and EPN reproduction. CONCLUSION: Our study is foundational to the development of attract-and-kill and autodissemination approaches involvingEPNs in fruitfly control. Furthermore,H. indicaandH. zealandicastrains showed the highest potential as biocontrol agentsagainst adultflies

Xanthomonas citri is a plant-pathogenic bacterium associated with a diverse range of host plant species. It has undergone substantial reclassification and currently consists of 14 different subspecies or pathovars that are responsible for a wide range of plant diseases. Whole-genome sequencing (WGS) provides a cutting-edge advantage over other diagnostic techniques in epidemiological and evolutionary studies of X. citri because it has a higher discriminatory power and is replicable across laboratories. WGS also allows for the improvement of multilocus sequence typing (MLST) schemes. In this study, we used genome sequences of Xanthomonas isolates from the NCBI RefSeq database to develop a seven-gene MLST scheme that yielded 19 sequence types (STs) that correlated with phylogenetic clades of X. citri subspecies or pathovars. Using this MLST scheme, we examined 2,911 Xanthomonas species assemblies from NCBI GenBank and identified 15 novel STs from 37 isolates that were misclassified in NCBI. In total, we identified 545 X. citri assemblies from GenBank with 95% average nucleotide identity to the X. citri type strain, and all were classified as one of the 34 STs. All MLST classifications correlated with a phylogenetic position inferred from alignments using 92 conserved genes. We observed several instances where strains from different pathovars formed closely related monophyletic clades and shared the same ST, indicating that further investigation of the validity of these pathovars is required. Our MLST scheme described here is a robust tool for rapid classification of X. citri pathovars using WGS and a powerful method for further comprehensive taxonomic revision of X. citri pathovars.