Rickettsia symbionts spread via mixed mode transmission, increasing female fecundity and sex ratio shift by host hormone modulating.

Heritable symbionts are common among animals in nature, but the molecular mechanisms underpinning symbiont invasions of host populations have been elusive. In this study, we demonstrate the spread of Rickettsia in an invasive agricultural pest, the whitefly Bemisia tabaci Mediterranean (MED), across northeastern China from 2018 to 2023. Here, we show that the beneficial symbiont Rickettsia spreads by manipulating host hormone signals. Our analyses suggest that Rickettsia have been horizontally acquired by B. tabaci MED from another invasive whitefly B. tabaci Middle East-Asia Minor 1 during periods of coexistence. Rickettsia is transmitted maternally and horizontally from female B. tabaci MED individuals. Rickettsia infection enhances fecundity and results in female bias among whiteflies. Our findings reveal that Rickettsia infection stimulates juvenile hormone (JH) synthesis, in turn enhancing fecundity, copulation events, and the female ratio of the offspring. Consequently, Rickettsia infection results in increased whitefly fecundity and female bias by modulating the JH pathway. More female progeny facilitates the transmission of Rickettsia. This study illustrates that the spread of Rickettsia among invasive whiteflies in northeastern China is propelled by host hormone regulation. Such symbiont invasions lead to rapid physiological and molecular evolution in the host, influencing the biology and ecology of an invasive species.

Current and future scenarios of suitability and expansion of cassava brown streak disease, Bemisia tabaci species complex, and cassava planting in Africa.

Cassava (Manihot esculenta) is among the most important staple crops globally, with an imperative role in supporting the Sustainable Development Goal of 'Zero hunger'. In sub-Saharan Africa, it is cultivated mainly by millions of subsistence farmers who depend directly on it for their socio-economic welfare. However, its yield in some regions has been threatened by several diseases, especially the cassava brown streak disease (CBSD). Changes in climatic conditions enhance the risk of the disease spreading to other planting regions. Here, we characterise the current and future distribution of cassava, CBSD and whitefly Bemisia tabaci species complex in Africa, using an ensemble of four species distribution models (SDMs): boosted regression trees, maximum entropy, generalised additive model, and multivariate adaptive regression splines, together with 28 environmental covariates. We collected 1,422 and 1,169 occurrence records for cassava and Bemisia tabaci species complex from the Global Biodiversity Information Facility and 750 CBSD occurrence records from published literature and systematic surveys in East Africa. Our results identified isothermality as having the highest contribution to the current distribution of cassava, while elevation was the top predictor of the current distribution of Bemisia tabaci species complex. Cassava harvested area and precipitation of the driest month contributed the most to explain the current distribution of CBSD outbreaks. The geographic distributions of these target species are also expected to shift under climate projection scenarios for two mid-century periods (2041-2060 and 2061-2080). Our results indicate that major cassava producers, like Cameron, Ivory Coast, Ghana, and Nigeria, are at greater risk of invasion of CBSD. These results highlight the need for firmer agricultural management and climate-change mitigation actions in Africa to combat new outbreaks and to contain the spread of CBSD.

Functional responses of two species of predatory mites (Acari: Phytoseiidae) to eggs and first-instar nymphs of Bactericera Gobica Logniova (Homoptera: Psyllidae).

The goji berry psyllid, Bactericera gobica Logniova (Homoptera: Psyllidae), is one of the most important pests on goji berry plants (Lycium barbarum L.), whose fruits are widely used in traditional Chinese medicine and food. However, chemical control is still the predominant control strategy of this pest. Recently, two species of predatory mites, Neoseiulus setarius Ma, Meng & Fan and Neoseiulus barkeri Hughes were found to be associated with B. gobica in China. To assess their predation potential against B. gobica, the functional responses of these two phytoseiid species feeding on different densities (2, 4, 8, 12, 16, 24 and 32 individuals) of B. gobica eggs and 1st instar nymphs were compared at a temperature of 25ºC ± 1º C. Logistic regression analysis revealed that both predatory mite species exhibited type Holling-II functional responses on eggs and 1st instar nymphs of B. gobica, with the predation number increased for both predators as the density of prey increased. Overall, N. setarius consumed more prey compared to N. barkeri across all levels of prey densities. Meanwhile, the highest attack rate (α = 0.0283), the lowest handling time (Th = 1.1324 h prey- 1), and the highest estimated maximum predation rate (T/Th = 21.19 prey day- 1) were all observed for N. setarius fed with 1st instar nymphs of B. gobica. These findings suggest that it is worthy considering utilizing N. setarius and N. barkeri as candidate biocontrol agents of B. gobica, with N. setarius appearing to be a more effective predator than N. barkeri.

A generalized risk assessment index for forecasting insect population under the effect of temperature.

Life history traits have been studied under various environmental factors, but the ability to combine them into a simple function to assess pest response to climate is still lacking complete understanding. This study proposed a risk index derived by combining development, mortality, and fertility rates from a stage-structured dynamic mathematical model. The first part presents the theoretical framework behind the risk index. The second part of the study is concerned with the application of the index in two case studies of major economic pest: the brown planthopper (Nilaparvata lugens) and the spotted wing drosophila (Drosophila suzukii), pests of rice crops and soft fruits, respectively. The mathematical calculations provided a single function composed of the main thermal biodemographic rates. This function has a threshold value that determines the possibility of population increase as a function of temperature. The tests carried out on the two pest species showed the capability of the index to describe the range of favourable conditions. With this approach, we were able to identify areas where pests are tolerant to climatic conditions and to project them on a geospatial risk map. The theoretical background developed here provided a tool for understanding the biogeography of Nilaparvata lugens and Drosophila suzukii. It is flexible enough to deal with mathematically simple (N. lugens) and complex (D. Suzukii) case studies of crop insect pests. It produces biologically sound indices that behave like thermal performance curves. These theoretical results also provide a reasonable basis for addressing the challenge of pest management in the context of seasonal weather variations and climate change. This may help to improve monitoring and design management strategies to limit the spread of pests in invaded areas, as some non-invaded areas may be suitable for the species to develop.

Effects of chlorantraniliprole on the development, fecundity and prey consumption of a non-specific predator, Rhynocoris fuscipes (Hemiptera: Reduviidae).

Transplant treatment with chlorantraniliprole (CAP) is a proactive approach to protect transplanted plants from pests during early establishment and has been comprehensively applied in tobacco fields in Guangdong Province, China. However, it is not known whether the high dose of CAP in transplant treatments has lethal or sublethal effects on the generalist predator Rhynocoris fuscipes Fabricius (Hemiptera: Reduviidae). To address this concern, the mortalities of R. fuscipes were assessed when 2nd instar larvae of R. fuscipes were in direct contact with or consuming CAP and when their eggs were exposed to CAP. Furthermore, 2nd instar nymphs R. fuscipes were long-term exposed to CAP until they reached adulthood, and their life table parameters were determined. After exposure to CAP, the activity of detoxification enzymes (P450, CaeE and GST) and the functional respond of R. fuscipes to their preys Agrotis ipsilon larvae were determined. In this study, CAP at all concentrations did not significantly increase the mortality of 2nd instar of R. fuscipes nymphs in comparison with the control. The detoxification enzyme (P450, CarE and GST) activities and the number of A. ipsilon larvae consumed by R. fuscipes in the transplant treatment were not affected by CAP after 3-d or long-term exposure. These results indicated that CAP was harmless to R. fuscipes according to IOBC protocols. However, during the treatment of 2nd instar nymphs with a label rate of 15 g AI/ha and a 5× label rate of 75 g AI/ha, CAP significantly prolonged the pre-adult and pre-oviposition periods, and treated adults had lower oviposition. Attention should be given to the time interval between transplant treatment and the release of this biocontrol agent into the field to minimize the impact of CAP on the predator R. fuscipes.

Peroxisome biogenesis factor PEX14 is crucial for survival and fecundity of female brown planthopper, Nilaparvata lugens (Stål).

Peroxisomes are ubiquitous cellular organelles participating in a variety of critical metabolic reactions. PEX14 is an essential peroxin responsible for peroxisome biogenesis. In this study, we identified the human PEX14 homolog in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae). N. lugens PEX14 (NlPEX14) showed significant topological similarity to its human counterpart. It is expressed throughout all developmental stages, with the highest expression observed in adult insects. Down-regulation of NlPEX14 through injection of NlPEX14-specific double-strand RNA impaired nymphal development. Moreover, females subjected to dsNlPEX14 treatment exhibited a significantly reduced lifespan. Additionally, we found abnormal ovarian development and a significant decrease in the number of eggs laid in NlPEX14-downregulated females. Further experiments support that the shortening of lifespan and the decrease in female fecundity can be attributed, at least partially, to the accumulation of fatty acids and reduced expression of vitellogenin. Together, our study reveals an indispensable function of NlPEX14 for insect reproduction and establishes a causal connection between the phenotypes and peroxisome biogenesis, shedding light on the importance of peroxisomes in female fecundity.

Biophoton emission-based approach of the effects of systemic insecticides on the survival of Eurydema ventralis Kolenati, 1846 (Hemiptera: Pentatomidae) and on the photosynthetic activity of oilseed rape.

The choice of effective crop protection technologies is a key factors in the economical production of oilseed rape. Insecticides belonging to the group of active substances butenolides and diamides are active substances available as seed treatments in oilseed rape and promising control tools in the crop protection technologies. Our laboratory experiment demonstrated that the experimental insecticides flupyradifurone and cyantraniliprole are both effective against Eurydema ventralis (Hemiptera: Pentatomidae) when used as a seed and in-crop treatments, but there is a fundamental difference in their insect mortality inducing effects. Flupyradifurone was found to have a total mortality 96 h after application based on basipetal translocation. In the case of cyantraniliprole, the insecticidal effect of the same treatment was 27% less. The experiment showed that the acropetal translocation of the tested active substances after seed treatment did not induce efficacy comparable to that of the basipetal translocation. The study of the biophoton emission of the plants demonstrated a verifiable correlation between the different application methods of the insecticides and the photon emission intensity per unit plant surface area. In conclusion, the systematic insecticides tested, in addition to having the expected insecticidal effect, interfere with plant life processes by enhancing photosynthetic activity.

Predicting suitable areas for Metcalfa pruinosa (Hemiptera: Flatidae) under climate change and implications for management.

Climate change is a prominent factor reshaping the distribution of invasive species. Metcalfa pruinosa (Say 1830) (Hemiptera: Flatidae), native to North America, has invaded other continents and poses a serious threat to various agricultural crops and the human residential environment. Understanding the distribution of M. pruinosa based on climatic conditions is a critical first step to prevent its further invasion. Therefore, based on its occurrence records and associated environmental variables, a Maxent model was developed to predict suitable areas for this species in the present and future on a global scale. The model exhibited outstanding performance, with a mean area under the receiver operating characteristic curve and true skill statistic values of 0.9329 and 0.926, respectively. The model also indicated that annual precipitation (Bio12) and max temperature of the warmest month (Bio5) were the key environmental variables limiting the distribution of M. pruinosa. Moreover, the model revealed that the current suitable area is 1.01 × 107 km2 worldwide, with southern China, southern Europe, and the eastern United States predicted to be the primary and highly suitable areas in the latter 2 regions. This area is expected to increase under future climate scenarios, mainly in the northern direction. The study's findings contribute to our understanding of climate change's impact on M. pruinosa distribution, and they will aid governments in developing appropriate pest management strategies, including global monitoring and strict quarantine measures.

Effects of Eucalyptus wood and leaf litter on saproxylic insects in the southeastern United States.

Although Eucalyptus is widely planted outside its native range for timber and pulp production, the effects of these exotic plantations on biodiversity relative to native semi-natural forests or plantations of native tree species remain incompletely understood. Here, we compare the diversity of saproxylic beetles (Coleoptera) and true bugs (Hemiptera) between non-native Eucalyptus benthamii Maiden and Cambage (Camden white gum) and native Pinus taeda L. (loblolly pine) stands on the upper Coastal Plain of South Carolina, U.S.A. We sampled insects emerging from logs of both species placed in both stand types after 1, 2, 6, and 12 months in the field. Beetle and true bug richness and diversity were both significantly lower from eucalypt than from pine wood. Moreover, the two communities were compositionally distinct. Whereas pine supported many species of host-specific phloeoxylophagous beetles, most species collected from eucalypts were mycophagous or predatory taxa capable of utilizing a wide range of hosts. Species richness did not differ between logs placed in eucalypt vs. pine stands but Shannon's diversity was significantly higher in the eucalypt stands, possibly due to greater sun exposure in the latter. Contrary to a previous study, we found no support for the idea that eucalypt litter reduces the diversity of saproxylic insects. Our findings add to the growing body of evidence that non-native plantations are less favorable to biodiversity than those consisting of native tree species.

Study on the gut symbiotic microbiota in long- and short-winged brown planthopper, Nilaparvata lugens (Stål).

The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the most important rice pests in Asia rice regions. BPH has monophagy, migration, rapid reproduction and strong environmental adaptability, and its control is a major problem in pest management. Adult BPH exhibit wing dimorphism, and the symbiotic microbiota enriched in the gut can provide energy for wing flight muscles as a source of nutrition. In order to study the diversity of symbiotic microbiota in different winged BPHs, this paper takes female BPH as the research object. It was found that the number of symbiotic microbiota of different winged BPHs would change at different development stages. Then, based on the 16S rRNA and ITS sequences, a metagenomic library was constructed, combined with fluorescent quantitative PCR and high-throughput sequencing, the dominant symbiotic microbiota flora in the gut of different winged BPHs was found, and the community structure and composition of symbiotic microbiota in different winged BPHs were further determined. Together, our results preliminarily revealed that symbiotic microbiota in the gut of BPHs have certain effects on wing morphology, and understanding the mechanisms underlying wing morph differentiation will clarify how nutritional factors or environmental cues alter or regulate physiological and metabolic pathways. These findings also establish a theoretical basis for subsequent explorations into BPH-symbiont interplay.

Differential expression of microRNAs in diapause and non-diapause gonads of Aspongopus chinensis Dallas (Hemiptera: Dinidoridae): implications for reproductive control.

Aspongopus chinensis Dallas, 1851 (Hemiptera: Dinidoridae), an edible and medicinal insect, usually found in China and Southeast Asia, offers substantial potential for various applications. The reproductive cycle of this particular insect occurs annually because of reproductive diapause, leading to inadequate utilization of available natural resources. Despite its considerable ecological importance, the precise mechanisms underlying diapause in A. chinensis are not yet well understood. In this study, we conducted an analysis of comparing the microRNA (miRNA) regulation in the diapause and non-diapause gonads of A. chinensis and identified 303 differentially expressed miRNAs, among which, compared with the diapause group, 76 miRNAs were upregulated and 227 miRNAs downregulated. The results, regarding the Enrichment analysis of miRNA-targeted genes, showed their involvement in several essential biological processes, such as lipid anabolism, energy metabolism, and gonadal growth. Interestingly, we observed that the ATP-binding cassette pathway is the only enriched pathway, demonstrating the capability of these targeted miRNAs to regulate the reproductive diapause of A. chinensis through the above essential pathway. The current study provided the role of gonadal miRNA expression in the control of reproductive diapause in A. chinensis, the specific regulatory mechanism behind this event remained unknown and needed more investigation.

Electrophysiological and behavioral responses of Tamarixia radiata (Hymenoptera: Eulophidae) to volatiles of nymphal Diaphorina citri (Hemiptera: Liviidae).

Huanglongbing (HLB), a devastating citrus disease caused by Candidatus Liberibacter asiaticus, is efficiently vectored by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). Tamarixia radiata (Waterston) plays a crucial role as an ectoparasitoid, preying on D. citri nymphs. By collecting and identifying headspace volatiles from fifth instar nymphs of D. citri using a gas chromatograph-mass spectrometer (GC-MS), we obtained a collection of 9 volatile compounds. These compounds were subsequently chosen to investigate the electrophysiological and behavioral responses of female T. radiata. At a concentration of 10 µg/µl, 9 compounds were compared with cis-3-hexen-1-ol (control), resulting in trans-2-nonenal inducing the highest relative electroantennogram (EAG) value, followed by hexanal, heptanal, n-heptadecane, tetradecanal, n-tetradecane, n-pentadecane, 1-tetradecanol, and 1-dodecanol. The top 5 EAG responses of female T. radiata to these compounds were further investigated through EAG dose-response experiments. The results showed positive dose-responses as concentrations increased from 0.01 to 10 µg/µl. In Y-tube olfactometer bioassays, female T. radiata exhibited a preference for specific compounds. They were significantly attracted to tetradecanal at a concentration of 10 µg/µl and trans-2-nonenal at 0.01 µg/µl, while no significant attraction was observed toward hexanal, heptanal, or n-heptadecane. Our report is the first to demonstrate that volatiles produced by D. citri nymphs attract T. radiata, which suggests that this parasitoid may utilize nymph volatiles to locate its host.

An at-leg pellet and associated Penicillium sp. provide multiple protections to mealybugs.

Beneficial fungi are well known for their contribution to insects' adaptation to diverse habitats. However, where insect-associated fungi reside and the underlying mechanisms of insect-fungi interaction are not well understood. Here, we show a pellet-like structure on the legs of mealybugs, a group of economically important insect pests. This at-leg pellet, formed by mealybugs feeding on tomato but not by those on cotton, potato, or eggplant, originates jointly from host secretions and mealybug waxy filaments. A fungal strain, Penicillium citrinum, is present in the pellets and it colonizes honeydew. P. citrinum can inhibit mealybug fungal pathogens and is highly competitive in honeydew. Compounds within the pellets also have inhibitory activity against mealybug pathogens. Further bioassays suggest that at-leg pellets can improve the survival rate of Phenacoccus solenopsis under pathogen pressure, increase their sucking frequency, and decrease the defense response of host plants. Our study presents evidences on how a fungi-associated at-leg pellet provides multiple protections for mealybugs through suppressing pathogens and host defense, providing new insights into complex insect × fungi × plant interactions and their coevolution.

Towards silent and efficient flight by combining bioinspired owl feather serrations with cicada wing geometry.

As natural predators, owls fly with astonishing stealth due to the serrated feather morphology that produces advantageous flow characteristics. Traditionally, these serrations are tailored for airfoil edges with simple two-dimensional patterns, limiting their effect on noise reduction while negotiating tradeoffs in aerodynamic performance. Conversely, the intricately structured wings of cicadas have evolved for effective flapping, presenting a potential blueprint for alleviating these aerodynamic limitations. In this study, we formulate a synergistic design strategy that harmonizes noise suppression with aerodynamic efficiency by integrating the geometrical attributes of owl feathers and cicada forewings, culminating in a three-dimensional sinusoidal serration propeller topology that facilitates both silent and efficient flight. Experimental results show that our design yields a reduction in overall sound pressure levels by up to 5.5 dB and an increase in propulsive efficiency by over 20% compared to the current industry benchmark. Computational fluid dynamics simulations validate the efficacy of the bioinspired design in augmenting surface vorticity and suppressing noise generation across various flow regimes. This topology can advance the multifunctionality of aerodynamic surfaces for the development of quieter and more energy-saving aerial vehicles.

Potential range shift of a long-distance migratory rice pest, Nilaparvata lugens, under climate change.

The biogeographical range shift of insect pests is primarily governed by temperature. However, the range shift of seasonal long-distance migratory insects may be very different from that of sedentary insects. Nilaparvata lugens (BPH), a serious rice pest, can only overwinter in tropical-to-subtropical regions, and some populations migrate seasonally to temperate zones with the aid of low-level jet stream air currents. This study utilized the CLIMEX model to project the overwintering area under the climate change scenarios of RCP2.6 and RCP8.5, both in 2030s and 2080s. The overwintering boundary is predicted to expand poleward and new overwintering areas are predicted in the mid-latitude regions of central-to-eastern China and mid-to-southern Australia. With climate change, the habitable areas remained similar, but suitability decreased substantially, especially in the near-equatorial regions, owing to increasing heat stress. The range shift is similar between RCP2.6-2030s, RCP2.6-2080s, and RCP8.5-2030s, but extreme changes are projected under RCP8.5-2080s with marginal areas increasing from 27.2 to 38.8% and very favorable areas dropping from 27.5 to 3.6% compared to the current climate. These findings indicate that climate change will drive range shifts in BPH and alter regional risks differently. Therefore, international monitoring programs are needed to effectively manage these emerging challenges.

Time and habitat structure shape insect acoustic activity in the Amazon.

Insects are the most diverse animal taxon on Earth and play a key role in ecosystem functioning. However, they are often neglected by ecological surveys owing to the difficulties involved in monitoring this small and hyper-diverse taxon. With technological advances in biomonitoring and analytical methods, these shortcomings may finally be addressed. Here, we performed passive acoustic monitoring at 141 sites (eight habitats) to investigate insect acoustic activity in the Viruá National Park, Brazil. We first describe the frequency range occupied by three soniferous insect groups (cicadas, crickets and katydids) to calculate the acoustic evenness index (AEI). Then, we assess how AEI varies spatially and temporally among habitat types, and finally we investigate the relationship between vegetation structure variables and AEI for each insect category. Overall, crickets occupied lower and narrower frequency bands than cicadas and katydids. AEI values varied among insect categories and across space and time. The highest acoustic activity occurred before sunrise and the lowest acoustic activity was recorded in pastures. Canopy cover was positively associated with cricket acoustic activity but not with katydids. Our findings contribute to a better understanding of the role of time, habitat and vegetation structure in shaping insect activity within diverse Amazonian ecosystems. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Seasonal migration pattern of an important rice pest, Nilaparvata lugens (Hemiptera: Delphacidae), on Hainan Island, China.

The brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae) (BPH), is a major, regionally migratory pest of rice in Asia. Despite intensive migratory studies, the seasonal migratory pattern of this species in the year-round breeding region (i.e., Hainan Island) remains largely unknown. To understand the migration dynamics, we conducted relevant research based on BPH light trap catches on Hainan in 2017-2022. Results showed that the occurrence dynamics of BPH in Hainan oscillated in different years and seasons. Overall, there are 4 migration peak periods on Hainan, with outbound peak periods in April-May and August-September and inbound peak periods in June and October. Trajectory and wind fields showed that in August-September, Hainan had complex meteorological conditions, and the outbound paths of BPH were variable, mainly landing in southeastern Guangxi and southwestern Guangdong. In contrast, April-May was influenced by southeasterly winds, with a wider outbound range and a further distance, landing along northeastern Vietnam from west to east toward Guangxi and Guangdong areas with time. Wind-rain fields, trajectory, and hydrogen isotope showed that in June, southwesterly winds transported BPH northward from the Indochina peninsula, where it was hindered by rainfall in the Leizhou Peninsula area and the migrants will be "rained out" into Hainan. Identically, in October, the interactions between northeasterly winds and rainfall belts on the southwest shore of Hainan increased the opportunities for BPH to migrate southward to reach Hainan. Our results suggest that Hainan is not only an important source of BPH migrating from East Asia but also plays the role of a bridge.

Effects of host plants on spotted lanternfly (Hemiptera: Fulgoridae) nymphal survival and development.

Spotted lanternfly, Lycorma delicatula (White), is an invasive planthopper from China, which was first detected in Berks County, PA, in 2014 and has since spread to adjacent states including New Jersey in 2018. Lycorma delicatula is a polyphagous species that gregariously feeds on over 172 known hosts. We investigated development on key host plants Ailanthus altissima (Miller) (Sapindales: Simaroubaceae), Juglans nigra (L.) (Fagales: Juglandaceae), Acer rubrum (L.) (Sapindales: Sapindaceae), and Vitis vinifera (L.) (Vitales: Vitaceae) for each instar to elucidate potential host use throughout the season and target monitoring efforts. Our study indicated significant differences in survivorship and time spent in each nymphal life stage between host plants. We applied a host suitability index as a function of survivorship and development for each host plant and instar, which indicated A. altissima and J. nigra as suitable hosts for all 4 nymphal instars. Vitis vinifera was highly suitable for first and second instars but had low indices for the third and fourth instars, although suitability of V. vinifera may have varied based on variety and age of the vine. Lycorma delicatula nymphs had the lowest survivorship and longest development time on A. rubrum across all 4 life stages, despite this being a preferred oviposition host. Host had a significant effect on the morphometrics we measured within the first and second instars.