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Background Invasions of a number of tree-feeding beetles have increased globally and pose a mounting threat to the world's trees, production forests and natural habitats. An in-depth understanding of the determinants of invasion potential of a given species and invasibility of novel environments can help forecast future invasions and avert undesirable socio-economic impacts. Here, we quantitatively assess the (multivariate) drivers of historic invasions of the coconut hispid Brontispa longissima (Coleoptera: Chrysomelidae) across the Asia-Pacific region and critically assess its invasion potential for other key coconut-growing regions. Results Genetic variation of B. longissima in its invaded range indicated multiple incursions, likely associated with (short-range) natural dispersal and (long-range) trade in ornamental palms and coconut plantlets. Interception records at China's ports of entry accentuate the role of traded planting material. The high fecundity and prolonged, yet adaptable, oviposition period of B. longissima further enhance the invasiveness of this species and aid its successful establishment. Coconut-growing areas are identified with high climatic suitability for B. longissima, and where strengthened biosecurity protocols can prevent future invasions. Conclusion A combined assessment of inter-country trade patterns, population genetics and species bio-ecology (e.g. climate-related development) illuminates the dispersal pathways of invasive species, assesses invasibility of particular geographies, guides quarantine interventions and thus can effectively avert future invasions. © 2019 Society of Chemical Industry.

Many of the most invasive plants are clonal, and clonal integration has been proposed as an important mechanism promoting invasiveness. When the availabilities of two essential resources are negatively correlated in space, clonal integration may benefit clonal plants through division of labor. We hypothesized that environments with reciprocal patchiness of light and soil water may induce division of labor, and nutrient addition may increase both the division of labor and the benefits of clonal integration. To test this, we grew pairs of connected and disconnected ramets of the clonal invader Mikania micrantha under negative spatial covariance of light and soil water such that the proximal ramets were grown under high light and low soil water conditions and the distal ramets were grown under low light and high soil water conditions. In half of the ramet pairs, both ramets of a pair received a nutrient addition treatment. The results showed that connection decreased the root to shoot ratio in proximal ramets and increased it in distal ramets, indicating that division of labor was induced. In addition, connection increased the root to shoot ratio of distal ramets more under high soil nutrient conditions than under low soil nutrient conditions, indicating that nutrient addition increased the division of labor. Connection increased plant biomass at the whole clonal fragment level, and this increase was larger under high soil nutrient conditions than under low soil nutrient conditions. This study showed, for the first time, that in environments with reciprocal patchiness of two essential resources, the capacity for division of labor and its influence on plant performance may depend on the availability of a third essential resource. Because invasive plants often can acquire a larger amount of soil resources than native plants, our study may also contribute to the understanding why clonality is related to invasiveness.

Opisina arenosella is one of the main pests harming coconut trees. To date, there have been few studies on the molecular genetics, biochemistry and physiology of O. arenosella at the transcriptional level, and there are no available reference genomes. Here, Illumina RNA sequencing combined with PacBio single-molecule real-time analysis was applied to study the transcriptome of this pest at different developmental stages, providing reference data for transcript expression analysis. Twelve samples of O. arenosella from different stages of development were sequenced using Illumina RNA sequencing, and the pooled RNA samples were sequenced with PacBio technology (Iso-Seq). A full-length transcriptome with 41,938 transcripts was captured, and the N50 and N90 lengths were 3543 bp and 1646 bp, respectively. A total of 36,925 transcripts were annotated in public databases, 6493 of which were long noncoding RNAs, while 2510 represented alternative splicing events. There were significant differences in the gene expression profiles at different developmental stages, with high levels of differential gene expression associated with growth, development, carbohydrate metabolism and immunity. This work provides resources and information for the study of the transcriptome and gene function of O. arenosella and provides a valuable foundation for understanding the changes in gene expression during development.

Background Red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae) is one of the most destructive insects for palm trees in the world. However, its genome resources are still in the blank stage, which limits the study of molecular and growth development analysis. Methods In this study, we used PacBio Iso-Seq and Illumina RNA-seq to first generate transcriptome from three developmental stages of R. ferrugineus (pupa, 7th larva, female and male) to increase our understanding of the life cycle and molecular characteristics of R. ferrugineus. Results A total of 63,801 nonredundant full-length transcripts were generated with an average length of 2,964 bp from three developmental stages, including the 7th instar larva, pupa, female adult and male adult. These transcripts showed a high annotation rate in seven public databases, with 54,999 (86.20%) successfully annotated. Meanwhile, 2,184 alternative splicing (AS) events, 2,084 transcription factors (TFs), 66,230 simple sequence repeats (SSR) and 9,618 Long noncoding RNAs (lncRNAs) were identified. In summary, our results provide a new source of full-length transcriptional data and information for the further study of gene expression and genetics in R. ferrugineus.

BackgroundRed palm weevil,Rhynchophorus ferrugineusOlivier, is one of the most destructive pests harming palm trees. However, genomic resources forR. ferrugineusare still lacking, limiting the ability to discover molecular and genetic means of pest control.MethodsIn this study, PacBio Iso-Seq and Illumina RNA-seq were used to generate transcriptome from three developmental stages ofR. ferrugineus(pupa, 7th-instar larva, adult) to increase the understanding of the life cycle and molecular characteristics of the pest.ResultsSequencing generated 625,983,256 clean reads, from which 63,801 full-length transcripts were assembled with N50 of 3,547 bp. Expression analyses revealed 8,583 differentially expressed genes (DEGs). Moreover, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that these DEGs were mainly related to the peroxisome pathway which associated with metabolic pathways, material transportation and organ tissue formation. In summary, this work provides a valuable basis for further research on the growth and development, gene expression and gene prediction, and pest control ofR. ferrugineus.

Tetrastichus brontispae Ferriere (Hymenoptera: Eulophidae) is an important natural enemy of the coconut leaf beetle Brontispa longissima (Gestro), a serious invasive pest on palm plants. Exposure to low temperature (2 °C) for 4, 24 and 48 h had an adverse effect on biological performance (survival, parasitism rate) of T. brontispae with immature parasitoids (eggs, larvae, and pupae) being more sensitive to low temperature than adults. Exposure to 2 °C for 24 h reduced the water content and increased the concentration of glycerol and trehalose, and activity of superoxidae in T. brontispae adults. Analysis of suppression subtractive hybridization indicated the integrative controlling and transcriptome regulation of the networks in the cold stress response of T. brontispae. Our study suggests that the allocation of energy reserves to either prevent or repair cold-induced damage may consume resources that could otherwise be invested in reproduction and consequently its ability to exert control on B. longissima.

The coconut black-headed caterpillar Opisina arenosella Walker, which is spreading in Southeast Asia and southern China, is a significant pest of palm trees. All life stages of this species were reared at 20, 23, 26, 29, 32 and 35 °C to understand the effect of temperature on the biology of O. arenosella. Total developmental time egg to adult generally was longest (≈114 days) at 20 °C, declined significantly with increasing temperature, and shortest (≈47 days) at 32 °C. Estimated lower developmental threshold temperature was 11.5 °C, and estimated effective accumulated temperature was 996.93°days. A third-order polynomial model estimated an optimal temperature of 32 °C for development. The predicted number of generations per year was calculated as 4–5 under average climatic conditions experienced in Hainan, China. The oviposition period ranged from 2 to 4 days and was longest at 26 °C while fecundity ranged from 30 to 180 total eggs laid per female and was greatest at 32 °C. The highest reproductive values were found at 32 °C. At this temperature, net reproductive rate (R0), generation time (T), intrinsic rate of increase (rm), finite rate of increase (λ) and doubling time (DT) were 64, 45 days, 0.09, 1.1 and 7.6 days, respectively. Knowledge of the effect of temperature on the life history characteristics of Opisina arenosella can be used to predict population growth, develop pest management strategies and mass produce insects for production of biocontrol agents.

Asecodes hispinarum (Hymenoptera: Eulophidae) is an endoparasitoid and an efficient biological control agent which attacks larvae of Brontispa longissima, a serious insect pest of Palmae plants in China. Odorant binding proteins (OBPs) are believed to be important for transporting semiochemicals through the aqueous sensillar lymph to the olfactory receptor cells within the insect antennal sensilla. No previous study has reported on OBPs in A. hispinarum. In this study, we conducted the large-scale identification of OBP genes from the antennae of A. hispinarum by using transcriptome sequencing. Approximately 28.4 million total raw reads and about 27.3 million total clean reads were obtained, and then 46,363 unigenes were assembled. Of these unigenes, a total of 21,263 can be annotated in the NCBI non-redundant database. Among the annotated unigenes, 16,623 of them can be assigned to GO (Gene Ontology). Furthermore, we identified 8 putative OBP genes, and a phylogenetic tree analysis was performed to characterize the 8 OBP genes. In addition, the expression of the 8 OBP genes in different A. hispinarum body tissues was analyzed by real-time quantitative polymerase chain reaction (qRT-PCR). The results indicated that the 8 OBP genes were expressed accordingly to sexes and tissues, but all highly expressed in antennae. The finding of this study will lay the foundation for unraveling molecular mechanisms of A. hispinarum chemoperception.

Background Euplatypus parallelus is a highly polyphagous invasive pest native to Central and South America. In recent years it has invaded many countries in Africa and Asia and resulted in considerable economic loss. In China it has been reported to have invaded Taiwan, and been also recorded in Hainan Province. Until now there has been no invasion into the mainland. In order to better manage this invasive pest, here we predicted the suitable area of E. parallelus in China by the Maxent model. Results The Maxent model predicted the potential distribution of E. parallelus with a test AUC value of 0.962 and a training AUC value of 0.978. Temperature seasonality (Bio_04), annual temperature range (Bio_07), annual precipitation (Bio_12) and mean temperature of the coldest quarter (Bio_11) were the strongest predictors of E. parallelus distribution with 32.1%, 19.8%, 15% and 10.4% contributions, respectively. The potential suitable area for E. parallelus was mainly distributed in the southeastern coast, the southwestern border, and Taiwan and Hainan provinces in China, and the highly suitable areas were located in the northern coast of Hainan Province and the southwestern coast of Taiwan Province. This pest prefers a stable, warm and rainy climate, which indicates that tropics and subtropics would be its ideal area. Conclusion Euplatypus parallelus has invaded Hainan and Taiwan in China. Measures should be taken to prevent it from spreading on these two islands. Moreover, strict quarantine, biological study and control measures are necessary to block its spread, invasion and damage, especially in these climate-suitable areas. © 2018 Society of Chemical Industry.

Brontispa longissima Gestro, known as the Coconut leaf beetle, is a leaf beetle that feeds on young leaves and damages seedlings and mature coconut palms. B. longissima has become an increasingly serious pest of coconuts in the Asian-Pacific region, especially over the last three decades. B. longissima broke out in Hainan Province, China in 2002. Quarantine and surveillance are the best prevention methods for introductions and further spread. Chemical spraying has been recommended, but foliar sprays pollute environments and are not suitable for certain areas and tall trees. To reduce pollution caused by chemical sprays, chemical sachets, Yejiaqing which is eluviation powder, were widely used to control B. longissima in scenic spots and cities in China. Great efforts have been put on biological controls. Metarhizium anisopliae which was isolated from B. longissima and formulated as a bioinsecticide was applied in China, as well as in Vietnam and Samoa. The larval parasite Asecodes hispinarum Boucek and pupal parasite Tetrastichus brontispae Ferriere were introduced into China in 2004 and have approved to be very functional. The parasitisation of T. brontispae and A. hispinarum was ~90% and ~100%, respectively. Field recoveries were made in some regions after parasitoids releasing however the parasitisation is not always so high. It is necessary to release substantial numbers of the parasite into suitable populations of B. longissima to ensure establishment. Environment and climate might effect on the survival and effectiveness of the parasitoid. Such information on control measure is necessary to study.

To optimise the production of Asecodes hispinarum Boucek (Hymenoptera: Eulophidae), a parasitoid of coconut leaf beetle, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), some of the factors affecting rates of parasitism, number of offspring produced per host and sex ratio of A. hispinarum were investigated. The numbers and sex ratio of A. hispinarum offspring per host reduced significantly at extreme low humidity (30% relative humidity [RH]), but there was no significant effect on parasitism. Photoperiod had no significant effects on any of the life traits tested. A. hispinarum was able to reproduce via arrhenotoky, and while increasing the proportion of female parents increased the number of parasitoids produced, the proportion of female offspring decreased. Older females showed a lower rate of parasitism than young females, however, maternal age did not affect the number or the sex ratio of offspring. Increasing the number of hosts offered to a pair of parasitoids significantly increased the n...

Larvae of Helicoverpa spp. can occasionally be found in Bollgard II® cotton (Gossypium hirsutum L.), raising concerns about the validity of current thresholds for their control. Experiments were conducted in two seasons to test these thresholds using artificial damage to different fruiting structures (squares or bolls or both) at three stages of cotton growth. At early flowering, Bollgard II® cotton plants tolerated 100% square removal from all plants without significant yield loss, indicating substantial compensation primarily through increased survival of subsequently produced fruit. This delay in the fruiting cycle, however, resulted in maturity delays of up to 6–13 d. At peak flowering, only 100% square removal or the combination of 30% boll damage and 100% square removal caused significant yield loss. Compensation in other treatments was primarily through increased boll weight. Square removal or square removal plus boll damage significantly delayed cotton maturity by about 5 d, but boll damage alone did not. At late flowering, the heaviest damage treatments (30% bolls damaged across 50% or all plants) significantly reduced yield, and there was a trend toward lower yield as damage increased, suggesting limited compensation. Boll damage had no effect on cotton maturation at late flowering. Damage distribution (all or half of the plants damaged) affected yield proportional to the amount of damage inflicted. Across all times and treatments, fiber quality was never affected to a degree that incurred price penalties commercially. In commercial fields, we rarely encountered damage levels equivalent to the heavier damage treatments, suggesting that current thresholds are adequate.

To verify current thresholds for Bollgard II® cotton in Australia, the impact of Helicoverpa spp. (Lepidoptera: Noctuidae) larvae on yield, development, and quality under various infestation intensities and durations, and stages of growth, was tested using small plot field experiments over two seasons. Infestation with up to 80 eggs m−1 of Helicoverpa armigera (Hubner) and Helicoverpa punctigera Wallengren showed that species, infestation level, and stage of growth had no significant effect on yields of seed-cotton or lint and on maturity and fibre quality. The duration of infestation of white flowers with H. punctigera neonates (maximum of every day for up to 4 weeks) had no impact on the yield of seed-cotton or lint, maturity, and fibre quality, but when 100% of flowers were infested (compared with 0 or 50%), seed-cotton and lint yields were significantly reduced and maturity was delayed. Infestation with up to 18 medium H. armigera larvae m−1 at several plant stages did not significantly affect yields of seed-cotton and lint, maturity, and fibre quality. A heliocide spray applied on a commercial farm at the current threshold resulted in a significantly higher lint yield, compared with a farm where no spray was applied. In conclusion, Bollgard II® cotton is highly resistant to Helicoverpa spp. infestation.

Cultivars of Bollgard II® cotton [Gossypium hirsutum L. (Malvaceae)] express the cry1Ac and cry2Ab genes from Bacillus thuringiensis Berliner (Bt) and are valuable for managing Helicoverpa spp. in Australia. However, substantial densities of Helicoverpa larvae can survive and feed on flowering Bollgard II® plants. Monitoring demonstrates that this larval survival is not because of physiological resistance. One hypothesis for this occurrence is that larvae have adapted their behaviour to reduce exposure to toxic compounds. The survival and distribution among cotton structures of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) larvae were examined using choice tests. Two hours after introduction to an arena, there were no differences between non-Bt cotton and Bollgard II® in the numbers of larvae on different plant structures. However, 24 and 48 h after their introduction, most larvae on Bollgard II® were on flowers (mean of 80.5%), whereas on non-Bt cotton, many larvae were also on flowers (58.5%), but there was also a considerable proportion (11%) on squares. In a subsequent experiment, we found similar numbers of larvae on the different structures of Bollgard II® plants regardless of whether their parents were collected as survivors on Bollgard II® cotton or non-Bt hosts. Cry1Ac and Cry2Ab expression varied among cotton structures, but there were no significant differences between the two popular Bollgard II® varieties used in this study. Bt toxin levels did not correlate well with the number of larvae among the structures from Bollgard II® plants. Thus, we conclude that although the distribution of Bt-susceptible larvae was somewhat different among plant structures on non-Bt and Bollgard II® cotton, history of survival on Bollgard II® cotton does not significantly impact on this behaviour.

The effect of ozone on the respiration of three species of adult stored-product Coleoptera was tested in an air-tight flask. Sitophilus oryzae (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst) adults were exposed to atmosphere containing 0.1, 0.2 or 0.4microg/ml initial ozone at 23-25 degrees C and 50% r.h. Carbon dioxide (CO(2)) production reflected the respiration rates of insects and was determined with a gas chromatograph (GC). The experiments showed that the effects of ozone on respiration had two distinct phases. Phase 1 involved a lower respiration rate of the adult stored-product Coleoptera under ozone atmosphere and reflected the need for insects to reduce ozone toxicity. After 1h, CO(2) production of S. oryzae was 3.19, 2.63, 2.27 and 1.99microl/mg for the ozone concentration of 0, 0.1, 0.2 and 0.4microg/ml, respectively. The results also showed that there were decreases in the rate of respiration in R. dominica and T. castaneum with an increase in ozone concentration. During phase 2, respiration of S. oryzae, R. dominica, and T. castaneum adults treated with ozone increased as the ozone degraded to oxygen. After 7h, the effect of ozone on CO(2) production, relative to the control, changed from a decrease to an increase. The findings in relation to control strategies were discussed.

The biology of Asecodes hispinarum Boucek (Hymenoptera: Eulophidae), a larva parasitoid imported from Vietnam as a classical biological control agent of coconut leaf beetle , Brontispa longissima (Gestro) (Coleoptera: Hispidae), was studied in quarantine in Hainan, China. The developmental stages of A. hispinarum were characterized from material reared at 22–26 °C and 70–80% RH. Development time (egg to adult) was 17.5 ± 2.1 days under these conditions. This study evaluated the life table parameters of A. hispinarum in a climate chamber at 16–30 °C, 80% RH and 12 h photo phase. Temperature had no effect on the sex ratio of parasitoid offspring. Mean adult longevity was inversely related to temperature with a maximum of 3.7 days at 16 °C and a minimum of 1.3 days at 30 °C. The lower developmental threshold estimated by the linear regression was 10.7 °C and 261.3 degree days. Most of the total lifetime complement of eggs of A. hispinarum was produced within 12 h of emergence. A. hispinarum that fed on 10% honey (w/v) lived significantly longer (2.98 days) than those fed on other energy sources, but showed no effects on parasitism, fecundity, emergence rate or sex ratio. A. hispinarum females parasitized all instars of larvae of B. longissima , but parasitism varied with host instar stage. Development of the parasitoid was not affected by the instar of the beetle host.