Tessaratoma Papillosa Research Articles

Seven New Species of Anastatus Motschulsky (Hymenoptera: Chalcidoidea: Eupelmidae) from China Identified Based on Morphological and Molecular Data.

Anastatus is the second-largest genus in the family Eupelmidae, with 150 species found worldwide and fourteen known species in China. Most species in this genus are the primary parasitoids of insect eggs, particularly those of Lepidoptera and Hemiptera, and several species have been used for the biological control of various insect pests. In this paper, seven new species of Anastatus Motschulsky, 1859 (Hymenoptera: Eupelmidae) from China are described, of which A. caeruleus Wang and Peng n. sp. and A. garygibsoni Zhou and Peng n. sp. were reared from the eggs of Tessaratoma papillosa (Hemiptera: Tessaratomidae), while A. daiyunensis Wang and Peng n. sp., A. makrysourus Zhou and Peng n. sp., A. polikiarkoudus Wang and Peng n. sp., A. taibaiensis Wang and Peng n. sp., and A. zdenekbouceki Zhou and Peng n. sp. were collected by malaise traps or sweeping. The new species are all described and illustrated based on female specimens, and the key to all 21 Chinese Anastatus species, based on females, is provided. Partial COI sequences of A. caeruleus n. sp., A. garygibsoni n. sp., and A. taibaiensis n. sp. are provided, and a phylogenetic reconstruction based on maximum likelihood analyses, while showing similar results at high taxonomic levels to our morphological feature classification results, provides additional information on the placement of Anastatus at the species level.

Effect of individual quick freezing treatment and cold storage on the host egg (Lepidoptera: Saturniidae) quality for the production of the parasitoid Anastatus japonicus Ashmead (Hymenoptera: Eupelmidae)

BackgroundThe augmentative release of the parasitoid species Anastatus japonicus Ashmead (Hymenoptera: Eupelmidae) is essential for managing the recent invasion of litchi stink bugs (Tessaratoma papillosa (Drury)) (Hemiptera: Tessaratomidae) in Taiwan. The mass release program in the spring targets this univoltine pest’s reproduction cycle. Low-temperature storage for the host eggs and parasitoids is required to maximize the production for the annual release program. This study aimed to enhance the shelf life of Samia cynthia (Lepidoptera: Saturniidae) eggs using the combination of refrigeration and individual quick freezing (IQF) as a storage treatment. Storage of A. japonicus in the IQF-treated S. cynthia eggs was evaluated to determine the optimal production process during the short preparation window before the release.ResultsThe influences of cold storage and IQF treatment on the host eggs were evaluated for different storage durations. The host quality was determined according to the emergence rate and female ratio of A. japonicus. The study’s results demonstrated that the host quality of S. cynthia eggs did not change significantly compared to the control group after 28 d of refrigeration at 7 °C. IQF treatment extended S. cyathia’s shelf life to 5 months without significantly affecting the host quality. Applying IQF at different developmental stages of the host eggs affected the parasitism rates of A. japonicus. Significantly higher emergence rates of A. japonicus were recorded in the eggs treated during the initial development (D0 to D2). However, storing parasitoids in the IQF-treated eggs under the current storage condition for one month at 12 °C significantly impacted the parasitoid’s emergence rate.ConclusionsThe results of this study highlight the potential benefits of the individual quick freezing technique. This technique didn’t alter the egg quality of S. cynthia, a crucial factor for the mass production of A. japonicus. The IQF treatment extends the shelf life of the host eggs to 5 months when stored at − 20 °C, a significant improvement compared to the 4-week shelf life without IQF treatment. This technology offers a promising and efficient approach for the mass production of A. japonicus and supports field releases. The treatment allowed for the stockpiling of host eggs during the off-season, which can help expedite the mass production of A. japonicus to fit an eight-week production window.

A novel fuzzy GRA-based possibility theory soft computing process for selection pest control methods

The study presents the effective approach that combines the ideal with non-ideal points, GRA, and possibility theory to handle uncertain information in selecting pest control methods within an MCDM problem. The proposed approach for selecting pest control methods can incorporate uncertainty information expressed by fuzzy numbers, possibilistic mean, and possibilistic variance. Decision-maker can comprehend the gaps between alternative solutions and the aspired outcomes, and it allows for the consideration of decision-making risks under a fuzzy environment. The study establishes an evaluation framework for selecting pest control methods by using the empirical study, and one obtains an appropriate pest control method for managing Tessaratoma papillosa in Taiwanese crops. Through the practical example, the proposed approach can be demonstrated the feasibility and efficiency.

Evaluation of Roasting and Grilling Effects on Chemical Composition, Volatile Profiles, and Toxicity of Stink Bugs (Tessaratoma papillosa): Implications for Utilization as Functional Food Ingredients.

The stink bug (Tessaratoma papillosa) is a highly popular edible insect in Thai traditional cuisine, but little research has investigated the effects of heat treatment on the quality of stink bugs. Therefore, we aimed to evaluate the effects of roasting and grilling on the chemical changes and volatile compounds of late nymph and adult stink bugs. In general, all treated samples showed increases in phenolic acid, tocopherols, and amino acid contents and a decrease in the content of fiber compared with raw stink bugs (p < 0.05). Cinnamic acid significantly increased by over 200% in late nymph insects and 30% in adult insects after roasting, whereas syringic acid decreased after cooking (p < 0.05). The most predominant volatile compound found in all samples was 5-methyl-octadecane and it decreased after cooking, while volatile alkane compounds increased after cooking. The processed sample extracts showed higher toxicity on oral cancer KB and cervical cancer Hela cells than on Vero cells. We have demonstrated that different cooking methods affected the chemical components which may result in quality attributes if stink bug is to be used as a functional ingredient/food. It may be helpful to improve the nutritional and functional values of stink bugs during deep processing.

Tessaratoma papillosa (Drury). [Distribution map

Abstract A new distribution map is provided for Tessaratoma papillosa (Drury). Hemiptera: Tessaratomidae. Main hosts: litchi ( Litchi chinensis ), longan ( Dimocarpus longan ), also Citrus spp.

Effects of abiotic factors on the immature development, adult performance, and field parasitism of mass-reared Anastatus parasitoids (Hymenoptera: Eupelmidae)

ABSTRACT Anastatus japonicus Ashmead, A. fulloi Sheng, and Wang, and A. dexingensis Sheng and Wang are vital biocontrol agents for the univoltine litchi stink bug Tessaratoma papillosa (Drury) in Taiwan as well as other invasive hemipteran and lepidopteran pests worldwide. An effective augmentative biocontrol programme was established with Anastatus parasitoids produced using eggs of the ailanthus silkmoth (Samia cynthia (Drury)) as factitious hosts. The study’s objective was to evaluate the immature development and adult performance of three Anastatus parasitoid species at 20, 25, and 30°C. The highest numbers of female and total progeny were produced by A. japonicus at 25°C and by A. dexingensis and A. fulloi at 20°C and 30°C, respectively. Anastatus japonicus had higher parasitism rates than A. dexingensis and A. fulloi at all three temperatures. The female ratios increased from 24.9% at 20°C to 70.4% at 30°C. The highest female ratios were recorded during the first two weeks of reproduction, and male progeny’s proportion gradually increased with female age. Anastatus japonicus was selected as the biocontrol agent for mass production based on its high fecundity and female progeny production rates. The field parasitism from the three release sites showed 30–40% of field parasitism during the first nine days of release. A significant reduction of field parasitism occurred after rainfall. The A. japonicus production system developed herein using the eggs of the factitious ailanthus silkmoth host could be commercialised to provide biocontrol against other hemipteran and lepidopteran pests species.

Pest incidence forecasting based on Internet of Things and Long Short-Term Memory Network

The infestation of litchi stink bugs (Tessaratoma papillosa) has always had a significant impact on the yield of longan plantations. Pest control is critical for farmers to detect and timely suppress the occurrence of pests while effectively reducing damages. Environmental factors, climate change in particular, have contributed to the growing population of pests whereas weather can vary in different terrains, locations, and time. Due to the geographical and topographical conditions of Taiwan, this study focuses on investigating fruit plantations on sloping land in subtropics with distinct seasonal changes. The article aims at forecasting meteorological data based on Long short-term memory network (LSTM) and identifying the correlation between pest infestation and environmental factors through Machine Learning (ML). In this section, the structure and experimental process of the research will be outlined. At the first stage, meteorological information of the experimented site is obtained through the self-designed IoT (Internet of Things) system and wireless long-distance transmission technology. Since meteorological information forecasted is displayed in time series, multi-layer LSTM and bidirectional LSTM are used to solve the problem. Finally, environmental data and field surveys conducted for pest surveillance will be employed to forecast the severity of pest infestation through KNN, SVM, and random forest models. The result of the experiment shows that LSTM performs well in weather forecasting with 96% R-Squared values whereas the accuracy rate of pest prediction conducted by Machine Learning (ML) is 85%. The study verifies that meteorological factors do affect pest incidence. For example, the population of litchi stink bugs increase easily under suitable temperature, humidity, and sunlight. LSTM is superior in providing solutions for long-range dependence in statistics. This article shall present regions with shifting weather patterns, meteorological conditions and time length forecasted corresponding to the oceanic climate, as well as the correlation between pest population and environmental factors.

Transcriptome Analysis for Identification of Genes Related to Growth and Development, Digestion and Detoxification, Olfaction in the Litchi Stink Bug Tessaratoma papillosa.

Tessaratoma papillosa is a major pest of Litchi chinensis and Dimocarpus longan. Adult and nymph secretions are not only harmful to plants but also to humans. At present, there are not a lot of research on T. papillosa, especially omics research. We used high-throughput sequencing technology to sequence the T. papillosa transcriptome and obtained 67,597 unigenes homologous to Halyomorpha halys (88.03%). Subsequently, RNA-SEQ and comparative analyses were performed on the 14 different developmental stages and tissues. A total of 462 unigenes related to growth and development, 1,851 unigenes related to digestion and detoxification, and 70 unigenes related to olfaction were obtained. Moreover, expression analysis showed that the T. papillosa major life activities genes are uniformly expressed across all developmental states. However, the adult midgut gene expression patterns were utterly different from that of the nymphs. Similarly, female fat body genes exhibited distinct expression patterns compared to that of males and nymphs. Thus, different developmental stages and physiological functions affect gene expression patterns. We also found that most of the differential genes were associated with cellular maintenance. This study will help understand the growth and development of litchi stink bugs, their choice of host plants, food digestion and detoxification, and their reproductive behavior. In addition, this result can provide reference information for some target genes in the process of control of T. papillosa.

Stage correlation of symbiotic bacterial community and function in the development of litchi bugs (Hemiptera: Tessaratomidae).

Bacterial symbionts of insects have been shown to play important roles in host fitness. However, little is known about the bacterial community of Tessaratoma papillosa which is one of the most destructive pests of the well-known fruits Litchi chinensis Sonn and Dimocarpus longan Lour in Oriental Region, especially in South-east Asia and adjacent areas. In this study, we surveyed the bacterial community diversity and dynamics of T. papillosa in all developmental stages with both culture-dependent and culture-independent methods by the third-generation sequencing technology. Five bacterial phyla were identified in seven developmental stages of T. papillosa. Proteobacteria was the dominant phylum and Pantoea was the dominant genus of T. papillosa. The results of alpha and beta diversity analyses showed that egg stage had the most complex bacterial community. Some of different developmental stages showed similarities, which were clustered into three phases: (1) egg stage, (2) early nymph stages (instars 1-3), and (3) late nymph stages (instars 4-5) and adult stage. Functional prediction indicated that the bacterial community played different roles in these three phases. Furthermore, 109 different bacterial strains were isolated and identified from various developmental stages. This study revealed the relationship between the symbiotic bacteria and the development of T. papillosa, and may thus contribute to the biological control techniques of T. papillosa in the future.

Temperature and Photoperiodic Response of Diapause Induction in Anastatus japonicus, an Egg Parasitoid of Stink Bugs.

Simple SummaryAnastatus japonicus Ashmead is an important egg parasitoid wasp and natural enemy of Tessaratoma papillosa. It is commercially used in biological control, and has effectively suppressed T. papillosa population for decades in China. In practice, medium temperature in spring always induces diapause in A. japonicus, leading to the delay of adult emergence and missing the best chance to control the pest. Accurately regulating the development of A. japonicus is a key technique for the production of biocontrol agents and field release applications. In this study, responsible environmental factors for the induction of diapause in A. japonicus were investigated. A short photoperiod and medium temperature led to diapause in A. japonicus. Second–third instar larva are the most sensitive stages to diapause stimuli. Diapausing mature larvae had a significantly higher survival rate after 180 days storage at 10 °C than that of nondiapausing mature larvae. Taken together, results suggest methods that could be exploited in the developmental regulation, field-release pretreatment technology, and long-term storage of A. japonicus.Anastatus japonicus Ashmead is a widely used biological control agent against stink bugs that can be successfully reared using the large eggs of the Chinese silkworm. In this study, environmental factors responsible for the induction of diapause in A. japonicus were investigated on host eggs of the Chinese silkworm. A. japonicus exhibited a facultative, mature larval diapause within its host eggs. Second–third instar larva are the most sensitive stages to diapause stimuli. The accumulation of diapause stimuli during all the larval stages maximized the diapause response. A short photoperiod of 10L:14D and temperature of 17 °C led to the occurrence of the highest diapause response, while a long photoperiod (14L:10D) and low temperatures (11 and 14 °C) prevented the diapause. A specific exposure period was required to reach high diapause incidence. Diapausing mature larvae had a significantly higher survival rate after 180 days storage at 10 °C than that of nondiapausing mature larvae. Taken together, results suggest methods that could be exploited in the developmental regulation, field-release pretreatment technology, and long-term storage of A. japonicus.

Evaluation of Sample Preservation Approaches for Better Insect Microbiome Research According to Next-Generation and Third-Generation Sequencing.

The microbial communities associated with insects play critical roles in many physiological functions such as digestion, nutrition, and defense. Meanwhile, with the development of sequencing technology, more and more studies begin to focus on broader biodiversity of insects and the corresponding mechanisms of insect microbial symbiosis, which need longer time collecting in the field. However, few studies have evaluated the effect of insect microbiome sample preservation approaches especially in different time durations or have assessed whether these approaches are appropriate for both next-generation sequencing (NGS) and third-generation sequencing (TGS) technologies. Here, we used Tessaratoma papillosa (Hemiptera: Tessaratomidae), an important litchi pest, as the model insect and adopted two sequencing technologies to evaluate the effect of four different preservation approaches (cetyltrimethylammonium bromide (CTAB), ethanol, air dried, and RNAlater). We found the samples treated by air dried method, which entomologists adopted for morphological observation and classical taxonomy, would get worse soon. RNAlater as the most expensive approaches for insect microbiome sample preservation did not suit for field works longer than 1 month. We recommended CTAB and ethanol as better preservatives in longer time field work for their effectiveness and low cost. Comparing with the full-length 16S rRNA gene sequenced by TGS, the V4 region of 16S rRNA gene sequenced by NGS has a lower resolution trait and may misestimate the composition of microbial communities. Our results provided recommendations for suitable preservation approaches applied to insect microbiome studies based on two sequencing technologies, which can help researchers properly preserve samples in field works.

Ophiocordyceps asiana and Ophiocordyceps tessaratomidarum (Ophiocordycipitaceae, Hypocreales), two new species on stink bugs from Thailand

Two new Ophiocordyceps species from Thailand, which belong to Ophiocordyceps nutans species complex and attack adult and nymph of stink bugs, are described: Ophiocordyceps asiana and O. tessaratomidarum. Molecular phylogenetic analyses of ITS and a combined sequence data of LSU, RPB1 and TEF1 revealed that these two new species are distinct from other known species in Ophiocordyceps nutans species complex. Based on the findings on morphological studies, they further support the naming of these two novel species. Ophiocordyceps asiana is parasitic on adult and nymph stink bugs, members of Coreidae and Pentatomidae which were recorded from China, Japan and Thailand, while O. tessaratomidarum is reported from Thailand for the first time and is only found as a parasite on adult stink bug, Tessaratoma papillosa (Tessaratomidae, Hemiptera). The fertile heads of O. asiana are shorter than reported for O. tessaratomidarum, and the colours of fertile heads producing teleomorph of these two species differs from each other by having strong reddish orange or light yellowish pink in O. asiana and pale yellow in O. tessaratomidarum.

Identification of Fruit Tree Pests With Deep Learning on Embedded Drone to Achieve Accurate Pesticide Spraying

Tessaratoma papillosa (Drury) first invaded Taiwan in 2009. Every year, T. papillosa causes severe damage to the longan crops. Novel applications for edge intelligence are applied in this study to establish an intelligent pest recognition system to manage this pest problem. We used a detecting drone to photograph the pest and employed a Tiny-YOLOv3 neural network model built on an embedded system NVIDIA Jetson TX2 to recognize T. papillosa in the orchard to determine the position of the pests in real-time. The pests' positions are then used to plan the optimal pesticide spraying route for the agricultural drone. Apart from planning the optimized spraying of pesticide for the spraying drone, the TX2 embedded platform also transmits the position and generation of pests to the cloud to record and analyze the growth of longan with a computer or mobile device. This study enables farmers to understand the pest distribution and take appropriate precautions in real-time. The agricultural drone sprays pesticides only where needed, which reduces pesticide use, decreases damage to the environment, and increases crop yield.

Population Monitoring, Egg Parasitoids, and Genetic Structure of the Invasive Litchi Stink Bug, Tessaratoma papillosa in Taiwan.

Simple SummaryThe litchi stink bug (LSB) was inadvertently introduced to Taiwan recently and has since become a severe pest with substantial economic losses. The aim of this study is therefore to improve our knowledge of this invasive pest through multiple approaches including population monitoring, surveillance of natural enemies, and population genetic analysis. Major findings include: (1) a population fluctuation trend that is largely similar to most native LSB populations, (2) a total of seven egg parasitoid species were discovered, two of which (Anastatus dexingensis and A. fulloi) being most abundant throughout the LSB infestation in Taiwan, and (3) the occurrence of multiple introductions of LSB to Taiwan. All these data represent a preliminary yet necessary step for the design of future integrated pest management strategies and would help mitigate negative impacts of this invasive pest in Taiwan.Here we assessed population dynamics, natural enemy fauna (with emphasis on egg parasitoid), and population genetic structure (based on mitochondrial DNA) of the invasive litchi stink bug (LSB), Tessaratoma papillosa in Taiwan. Our major findings include: (1) fluctuations of LSB in numbers of adults, mating pairs, and egg masses over a 2-year period in Taiwan generally resemble those in the native populations; (2) Anastatus dexingensis and A. fulloi are among the most dominant LSB egg parasitoids, with the former consistently outnumbering the latter throughout Taiwan; (3) the presence of two genetically distinct clades suggests LSB in Taiwan most likely derived from multiple invasions. All these data practically improve our understanding of this invasive insect pest, particularly its ecological and genetic characteristics in the introduced area, which represents critical baseline information for the design of future integrated pest management strategies.

Functional response of adult Hierodula patellifera (Serville, 1839) (Mantodea: Mantidae) to Tessaratoma papillosa (Drury) (Hemiptera: Tessaratomidae)

The litchi stink bug, Tessaratoma papillosa (Drury) (Hemiptera: Tessaratomidae), is a serious pest in the longan and litchi orchards in China. At present, the control of T. papillosa is heavily based on the use of insecticides, and the environmentally-friendly alternative strategies are urgently needed. The praying mantis, Hierodula patellifera (Serville, 1839) (Mantodea: Mantidae) and T. papillosa coexist in orchards. We assessed the potential of H. patellifera adults serving as a bio-control agent against T. papillosa by observing the predatory behavior of the mantis when the bugs were offered at different densities and different developmental stages under laboratory condition. The results showed that H. patellifera adults could be an effective biological control agent against T. papillosa as it exhibited Holling type II and type III functional response in the laboratory. Its consumption rates of prey increased with an increase in the density of prey offered but its search efficiency declined. The proportions of 1st -4th instar T. papillosa nymphs consumed by H. patellifera were higher than the other stages. Our results indicated that H. patellifera can be an effective biocontrol agent of T. papillosa, and these findings can guide the mass production efforts of this mantis.

Insights into the venom protein components of the egg parasitoid Anastatus japonicus (Hymenoptera: Eupelmidae).

Parasitoid venom is composed of a complex mixture of various active substances with different biological functions and is injected in the host during the parasitoid oviposition. Anastatus japonicus (Hymenoptera: Eupelmidae) is an egg parasite of Tessaratoma papillosa (Hemiptera: Tessaratomidae). Although the venom of this egg parasitoid plays an important role in the parasitic process, relatively little work has been done to address the mechanism. In the present study, proteomic analysis was performed to identify the proteins that play an important role in the parasitic process of A. japonicus. A total of 2084 proteins were identified, including 81 putative venom proteins, most of which were identified as Hexamerin, Chitinase 2, Calreticulin, Heat shock protein 83-like, Serine protease, Arginine kinase, Phosphoserine aminotransferase and Actin protein. Together the before (Be) and after (Af) parasitization venom contains 1628 proteins, including 212 DEPs with 181 and 31 significantly up-regulated and down-regulated respectively. In addition, 10 differentially expressed proteins (DEPs) with fold change ≥8.71 were subjected to RT-qPCR to validate the proteomic data. The differential expression analysis revealed that nine proteins were specifically present in the pre-parasitic venom, whereas 26 proteins were specific to the post-parasitic treatments. Results of RT-qPCR analysis showed high expression of the selected DEPs which further validated our proteomics data. These new proteomic data greatly enrich our current knowledge about key venom proteins associated with parasitic process in A. japonicus and contribute to better understanding of the parasitic mechanisms leading to the development of new biological control strategies. © 2020 Society of Chemical Industry.

Damage and Control Measures of Tessaratoma papillosa in Luzhou City

Tessaratoma papillosa Drury was one of main pests of Litchi chinensis Sonn. and Dimocarpus longan Lour. in Luzhou city,and they were distributed in Longmatan District, Jiangyang District, Xuyong County, Hejiang County and Luxian County. Because of difficulties for pest control, it was suggested for the relevant departments of Luzhou city that a certain control strategy should be taken to reduce and control the quantity of T. papillosa Drury.

The isolation and identification of pathogenic fungi from Tessaratoma papillosa Drury (Hemiptera: Tessaratomidae).

BackgroundLitchi stink-bug, Tessaratoma papillosa Drury (Hemiptera: Tessaratomidae), is one of the most widespread and destructive pest species on Litchi chinensis Sonn and Dimocarpus longan Lour in Southern China. Inappropriate use of chemical pesticides has resulted in serious environmental problems and food pollution. Generating an improved Integrated Pest Management (IPM) strategy for litchi stink-bug in orchard farming requires development of an effective biological control agent. Entomopathogenic fungi are regarded as a vital ecological factor in the suppression of pest populations under field conditions. With few effective fungi and pathogenic strains available to control litchi stink-bug, exploration of natural resources for promising entomopathogenic fungi is warranted.Methods & ResultsIn this study, two pathogenic fungi were isolated from cadavers of adult T. papillosa. They were identified as Paecilomyces lilacinus and Beauveria bassiana by morphological identification and rDNA-ITS homogeneous analysis. Infection of T. papillosa with B. bassiana and P. lilacinus occurred initially from the antennae, metameres, and inter-segmental membranes. Biological tests showed that the two entomopathogenic fungi induced high mortality in 2nd and 5th instar nymphs of T. papillosa. B. bassiana was highly virulent on 2nd instar nymphs of T. papillosa, with values for cadaver rate, LC50 and LT50 of 88.89%, 1.92 × 107 conidia/mL and 4.34 days respectively.DiscussionThis study provides two valuable entomopathogenic fungi from T. papillosa. This finding suggests that the highly virulent P. lilacinus and B. bassiana play an important role in the biocontrol of T. papillosa in China. These pathogenic fungi had no pollution or residue risk, and could provide an alternative option for IPM of litchi stink-bug.

Molecular basis of peripheral olfactory sensing during oviposition in the behavior of the parasitic wasp Anastatus japonicus

Anastatus japonicus is a parasitic wasp and natural enemy of the litchi pest Tessaratoma papillosa, and for decades in China, A. japonicus has been mass-reared inside the eggs of Antheraea pernyi to control T. papillosa. A series of experiments was performed to explore the olfactory mechanism underlying the oviposition behavior of A. japonicus. First, a transcriptomic analysis was performed on the antennae of A. japonicus, and the resulting assemblies led to the generation of 70,473 unigenes. Subsequently, 21,368 unigenes were matched to known proteins, 48 odorant receptors (ORs) (including Orco) and 13 antennal ionotropic receptors (IRs) (including the co-receptors IR8a and IR25a) were identified and predicted to form complete open reading frames (ORFs). The FPKM (fragments per Kb per million reads) values and RT-PCR results showed that AjapOrco, AjapOR10, AjapOR27, AjapOR33 and AjapOR35 were either highly abundant or expressed specifically in the olfactory organs. Furthermore, AjapOrco silencing resulted in a significant decrease in both the parasitism rate and the host-seeking time of A. japonicus, whereas dsRNA injection showed that IR8a and IR25a did not produce significant behavioral changes, suggesting that the oviposition behavior of A. japonicus is more reliant on OR-based pathways than IR-based pathways.Our previous GC-MS data derived twenty-nine compounds which were abundent from these host plants and host insects. We performed electrophysiological and oviposition assays on A. japonicus, and eight odorants were found to elicit a significant electroantennogram (EAG) response. Among these odorants, β-Caryophyllene, Undecane, (E)-α-Farnesene (+)-Aromadendrene and Cis-3-Hexen-ol had strong attractant effects on oviposition, whereas 2-Ethyl-1-Hexan-ol, Ethyl Acetate and α-Caryophyllene had a strong repellant effects. Thus, these chemicals might influence oviposition guidance/repulsion behavior in A. japonicus.To further explore the target ORs that are tuned to the functional odorants, the nine candidate ORs described above were silenced by RNA interference, and the results showed that a large decrease in the EAG response of all the tested functional odorants in the AjapOrco-silencing group. In addition, the AjapOR35-silencing group showed a significant decrease in the EAG response to β-Caryophyllene and (E)-α-Farnesene, indicating that AjapOR35 is tuned to these two oviposition attractants β-Caryophyllene and (E)-α-Farnesene. Further binary-choice oviposition assays showed that the oviposition attractant effect of β-Caryophyllene and (E)-α-Farnesene vanished after AjapOR35 was silenced, indicating that the emission of these attractants from host plants can guide A. japonicus to locate eggs for ovipositioning and indicated that AjapOR35 is correlated with the olfactory detection oviposition behavior of this species. This study provides a better understanding of the molecular basis and functional chemicals underlying the oviposition behavior of A. japonicus, and the results may help improve biocontrol approaches.

Transcriptome sequencing of Tessaratoma papillosa antennae to identify and analyze expression patterns of putative olfaction genes

Studies on insect olfaction have increased our understanding of insect’s chemosensory system and chemical ecology, and have improved pest control strategies based on insect behavior. In this study, we assembled the antennal transcriptomes of the lychee giant stink bug, Tessaratoma papillosa, by using next generation sequencing to identify the major olfaction gene families in this species. In total, 59 odorant receptors, 14 ionotropic receptors (8 antennal IRs), and 33 odorant binding proteins (28 classic OBPs and 5 plus-C OBPs) were identified from the male and female antennal transcriptomes. Analyses of tissue expression profiles revealed that all 59 OR transcripts, 2 of the 8 antennal IRs, and 6 of the 33 OBPs were primarily expressed in the antennae, suggesting their putative role in olfaction. The sex-biased expression patterns of these antenna-predominant genes suggested that they may have important functions in the reproductive behavior of these insects. This is the first report that provides a comprehensive resource to future studies on olfaction in the lychee giant stink bug.