Stink Bug Nezara Viridula Research Articles

Pengembangan teknologi pengendalian hama utama kacang hijau menggunakan biopestisida

Hama merupakan salah satu kendala utama dalam upaya peningkatan produksi kacang hijau di Indonesia. Saat ini, pengendalian konvensional menggunakan pestisida sintetik kurang berhasil karena populasi dan kerusakan akibat hama masih tinggi. Penelitian ini bertujuan untuk mengembangkan biopestisida sebagai teknologi pengendalian hama utama kacang hijau yang dibandingkan dengan efikasi pestisida sintetik. Penelitian ini dilaksanakan menggunakan rancangan acak kelompok, lima perlakuan diulang lima kali. Perlakuan yang diuji, yaitu P1: aplikasi serbuk biji mimba (SBM), virus ulat grayak (Virgra) dari Spodoptera litura nuclear polyhedrosis virus, dan konidia cendawan entomopatogen Beauveria bassiana (BeBas) secara preventif; P2: aplikasi SBM, Virgra, dan BeBas berdasarkan ambang ekonomi (AE); P3: aplikasi pestisida sintetik sesuai jadwal; P4: aplikasi pestisida sintetik berdasarkan AE; dan P5: tanpa pengendalian (kontrol). Hasil penelitian menunjukkan bahwa hama yang berkembang adalah ulat grayak (Spodoptera litura (Fabricius)), kutukebul (Bemisia tabaci (Gennadius)), Empoasca sp., Megalurothrips usitatus (Bagnall), kepik coklat (Riptortus linearis (Fabricius)), kepik hijau (Nezara viridula (Linnaeus)), dan hama penggerek polong (Maruca testulalis (Geyer)). Aplikasi biopestisida SBM, Virgra, dan BeBas secara preventif dan aplikasi pestisida sintetik sesuai jadwal efektif menekan populasi hama utama kacang hijau, sedangkan aplikasi biopestisida dan pestisida sintetik berdasarkan AE tidak mampu menekan perkembangan populasi hama utama. Aplikasi biopestisida secara preventif maupun berdasarkan AE lebih aman terhadap kelangsungan hidup musuh alami, sedangkan aplikasi pestisida sintetik dapat membunuh musuh alami yang ada. Biopestisida SBM, Virgra, dan BeBas yang diaplikasikan secara preventif dan terintegrasi berpotensi sebagai inovasi teknologi pengendalian hama utama kacang hijau untuk menggantikan pestisida sintetik.

RNAi-mediated mortality in southern green stinkbug Nezara viridula by oral delivery of dsRNA.

The southern green stinkbug, Nezara viridula (Hemiptera: Pentatomidae), is an important emerging polyphagous pest infesting soybean in the United States, Brazil and Argentina. The indiscriminate use of synthetic insecticides to control stinkbugs has limited the effectiveness of current management strategies. Alternatively, RNA interference (RNAi) has emerged as a novel mode of action to control pests in an eco-friendly manner. Here, we assessed the potential of RNAi technology by oral delivery of double-stranded RNA (dsRNA) for the control of N. viridula. Initially, ten candidate genes were tested by microinjection assay to select the best target genes for oral delivery. Seven genes resulted in more than 90% mortality after microinjection. To evaluate RNAi efficacy by oral delivery of dsRNA, five genes were tested by feeding the insects on gene-specific dsRNA mixed with an artificial diet. Significant mortality of 43% and 45% was observed after 14 days of treatment with dsαCop and dsvATPase A, respectively. To elucidate the lower RNAi efficacy via oral delivery of dsRNA, ex vivo dsRNA degradation in the saliva and the midgut juice was performed, which indicated that the reduced RNAi efficacy is accompanied by a rapid degradation of dsRNA by digestive secretions. This study proves that RNAi can be triggered by orally delivered dsRNA in N. viridula and can be exploited to control this economically important pest. The reduced stability of dsRNA in saliva and midgut that was observed indicates a need to further improve RNAi efficacy, for example by use of specific formulations.

EFEKTIVITAS MINYAK BIJI Jatropha curcas MENGENDALIKAN KEPIK PENGHISAP POLONG KEDELAI Nezara viridula (HEMIPTERA: PENTATOMIDAE) DI RUMAH KASA

Green Stink Bug Nezara viridula (Hemiptera: Pentatomidae) is an important pest on soybean. The yield losses could be qualitatively and quantitatively. Controlling by using synthetic insecticide caused negative impact. Hence, controlling by using botanical insecticide was as an alternative. The study was conducted at wire house, to know the effect of J. curcas seed oil concentration on N. viridula mortality, pod damaged, empty pod, seed damaged and dry seed weight. The J. curcas seed oil was obtained by Soxhlet Extractor. The concentration of J. curcas seed oil as the treatment, viz. 0% (control); 0.125; 0.25 dan 0.5% (volume oil/volume solution,v/v), and the water as solution applied on soybean plant which was infested of ten N. viridula adult. The result showed all variable observed affected by J. curcas seed oil concentration. The 0.25 and 0.5% concentration showed the mortality reached 95.0 and 100% at 6 days after treatment, while, pod damaged was 7.34 and 1.84%; empty pod was 25.32%, seed damaged was 3.72 and 0.78% and weight of dry seed was 9.94 and 10.44 g. The weight of dry seed at control treatment was 5.52 g. The J. curcas seed oil at 0.5% of concentration has a potency to control N. viridula on soybean plant. There is a need further study to know the effectivity on soybean in the field.

Entrapment of Bradysia paupera (Diptera: Sciaridae) by Phaseolus vulgaris (Fabaceae) plant leaf

Flies of the genus Bradysia (Diptera, Sciaridae) are considered as major insect pests of greenhouse-grown horticultural crops. The ability of hooked trichomes of the French bean Phaseolus vulgaris to impale and entrap herbivorous insects thus resulting in insect reduced longevity, reproduction and larval mortality is well known. The present study investigates under laboratory conditions the ability of hooked trichomes of bean leaves to entrap fungus gnats Bradysia paupera, in order to estimate the reduction of their population. We characterized the entrapment mechanism of hooked trichomes towards B. paupera using cryo-scanning electron microscopy, and evaluated the silicon distribution in hooked trichomes with the energy dispersive X-ray microanalysis. We evaluated the trapping efficiency of hooked trichomes in fertilized and unfertilized bean plants towards B. paupera, in comparison with insects feeding on the plant leaf such as black bean aphid Aphis fabae and young stages of the southern green stinkbug Nezara viridula. For B. paupera, we recorded about 30% of entrapped insects in unfertilized plants. Considering the number of entrapped insects in relation to the leaf surface, the percentage of entrapped insect was higher in unfertilized than in fertilized plants having lower density of hooked trichomes. The presence of P. vulgaris plants in greenhouses could represent a useful method in integrated pest management to reduce Bradysia spp. population.

A transcriptomic and proteomic atlas of expression in the Nezara viridula (Heteroptera: Pentatomidae) midgut suggests the compartmentalization of xenobiotic metabolism and nutrient digestion

BackgroundStink bugs are an emerging threat to crop security in many parts of the globe, but there are few genetic resources available to study their physiology at a molecular level. This is especially true for tissues such as the midgut, which forms the barrier between ingested material and the inside of the body.ResultsHere, we focus on the midgut of the southern green stink bug Nezara viridula and use both transcriptomic and proteomic approaches to create an atlas of expression along the four compartments of the anterior-posterior axis. Estimates of the transcriptome completeness were high, which led us to compare our predicted gene set to other related stink bugs and Hemiptera, finding a high number of species-specific genes in N. viridula. To understand midgut function, gene ontology and gene family enrichment analyses were performed for the most highly expressed and specific genes in each midgut compartment. These data suggested a role for the anterior midgut (regions M1-M3) in digestion and xenobiotic metabolism, while the most posterior compartment (M4) was enriched in transmembrane proteins. A more detailed characterization of these findings was undertaken by identifying individual members of the cytochrome P450 superfamily and nutrient transporters thought to absorb amino acids or sugars.ConclusionsThese findings represent an initial step to understand the compartmentalization and physiology of the N. viridula midgut at a genetic level. Future studies will be able to build on this work and explore the molecular physiology of the stink bug midgut.

First detection of the Nearctic parasitoid species Trichopoda pennipes (Fabricius) (Diptera: Tachinidae) in Egypt

Specimens of the feather-legged fly, Trichopoda pennipes (Fabricius) (Diptera: Tachinidae), which parasitize adults of the southern green stink bug Nezara viridula (L.) (Hemiptera: Pentatomidae), have been detected in Giza, Egypt. This is the first record of this Nearctic species with its genus (Trichopoda) and its tribe (Gymnosomatini) in Egypt. T. pennipes is known as an endoparasitoid of many true bug hosts, the pests of various crops, and it could have a potentiality to control these pests in addition to N. viridula, which is known to be its principal host. Taxonomy and diagnosis of the detected parasitoid species in addition to a checklist of the subfamily Phasiinae in Egypt are provided. Colored photographs of the parasitoid larval and adult stages and parasitized host are provided as well.

Development of the elements of the biological system for protecting crops against the southern green stink bug Nezara viridula L. (Hemiptera: Pentatomidae) in Krasnodar Krai

The article considers the issues related to the development of the methods of biological crop protection against the adventive species of pentatomides (Pentatomidae, Hemiptera) – the southern green stink bug Nezara viridula L. 1758. One of the main factors contributing to the significant spread of this multinucleated pest is the lack of effective control systems of this species, in particular, poor knowledge of local entomophages species. A number of the biological peculiarities of a stinkbug has been studied. For the first time in the Russian Federation, infection of the N. viridula eggs with the entomophage Trissolcus basalis Woll. 1858 (Hymenoptera: Scelionidae) was determined We found that to control Nezara in such crops as soybeans, tomatoes and tobacco, it is possible to use the Fitoverm-M preparation (active ingredient – aversectin-C, 2 g/l).

Štetne stenice vrežastih biljaka

Plants from the family Cucurbitaceae are attacked by many polyphagous pest insect species, as field and mole crickets, aphids, flea beetles and noctuids. Among mentioned pests, certain species of true bugs, order Hemiptera, can be found on vegetative and generative parts of the named plants. True bugs feed on all above ground plant parts sucking plant juices and causing damage to the fruits that can be in the form of deformation and/or occurrence of smaller or larger necrotic spots. These freckles are the result of nutrition ie. insertion of the stilets into the plant tissue, which affects the market value of the obtained fruits. Among the species most important for cucumber, watermelon, pumpkin and zucchini in our area, the most common are representatives of the family Miridae, genus Lygus sp. The most commonly encountered species are L. rugulipennis Popp. and L. pratensis L. Among the representatives of the family Pentatomidae, the most common are the Green Vegetable Stink Bug Nezara viridula L. and the Brown Marmorated Stink Bug Halyomorpha halys Stål, which feed mainly on cucumbers. Symptoms of damage from all true bugs species are similar, from small sting points, which are lighter at the beginning, to later necrotic spots, to the deformation of the fruits damaged during formation, to the smaller or larger necrotic spots seen on the mature fruits. Integrated approach in control of these pests should be applied, with good phytosanitary measures, weed control around the fields, and the like, although protection most often relies on the use of chemical insecticides. In our country, the list of registered pest control chemicals is not long. Beside that, true bugs cause most damage on ripening fruits, making the list of available insecticides even shorter.

Development of efficient RNAi in Nezara viridula for use in insecticide target discovery.

Stink bugs are an emerging pest in many regions of the world but their molecular biology is still poorly understood. While several transcriptomes are available, the lack of validated gene manipulation tools like RNA interference (RNAi) in species such as the southern green stinkbug Nezara viridula precludes the characterization of individual genes in vivo. Such tools are particularly useful in performing high-throughput screens to search for essential genes that can be prioritized as potential insecticide targets. Here, we developed and optimized an efficient RNAi in N. viridula for use in insecticide target discovery and beyond. The visible marker Sex combs reduced and the essential gene Actin were used to verify the usability and efficiency of RNAi by microinjection at both the adult and nymphal stages, respectively, with nymphal approach presenting significant advantages. Following validation, RNAi was then used to measure lethality following the knockdown (KD) of two genes that are known insecticide targets, Chitin synthase, and Acetyl-CoA carboxylase. The KD of each gene resulted in >75% corrected mortality. These results indicate that RNAi is an effective tool in N. viridula and set a benchmark to evaluate potential targets in future RNAi screens aimed at insecticide target discovery.

Biomechanics of fore wing to hind wing coupling in the southern green stink bug Nezara viridula (Pentatomidae)

Stink bugs have wing coupling mechanisms to synchronize flapping of their wings. The wing coupling is performed through a clamp-like structure on the fore wing (i.e. hemelytron) and a rolled margin on the hind wing. Here we used modern imaging techniques to investigate structural characteristics and material composition of the wing coupling of the stink bug Nezara viridula. We found that the surfaces of the clamp-like structure and the rolled margin are covered by highly-sclerotized microtrichia, which are expected to reduce friction between the wings during flapping flight. Micro-force measurements showed that fore and hind wings can be coupled only in certain angles ranging from 40.6° to 267.7° The results further showed that the force required to uncouple fore and hind wings is maximal for a range of angles which they make with each other during flight (127.1°–238.9°). In contrast to previous observations on some other insect species, the removal of the wing coupling in stink bugs led to complete loss of flight ability. In summary, we concluded that the shape, material composition and orientation of the coupling structure guarantee a robust fore wing to hind wing coupling during flight and a fast, easy uncoupling at rest. Statement of significanceAlthough the coupling mechanism of insect fore wing and hind wing has long been described, the functionality of this mechanism still remains largely unknown. In the present work, using a combination of modern imaging techniques and mechanical testing, we studied the functional morphology of the fore wing-hind wing coupling mechanism of the stink bug Nezara viridula. Our study reveals the crucial role of the mechanism in the flight ability of the stink bug and sheds light on the structure-property-function relationships of the functional diptery in insects.

Kaolin nano-powder effect on insect attachment ability

The present study investigates under controlled conditions the effect of kaolin particle film on reduction of insect attachment ability. Two economically important polyphagous insect pests characterized by different attachment devices were tested, the Southern green stink bug Nezara viridula (Heteroptera: Pentatomidae) and the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae). We performed traction force experiments with females pulling on treated (covered with kaolin particle film) and untreated (control) natural (leaf surfaces with different morphological traits) and artificial (hydrophilic and hydrophobic glass) surfaces. The data demonstrated that insect adhesion is heavily affected by kaolin particle film in both tested species. The degree of reduction of insect adhesion to the treated substrates compared with the untreated ones differed according to the kind of treated substrate owing to its initial wettability and morphology (presence of trichomes). To unravel the insect adhesion reduction mechanism of kaolin particle film, we evaluated the safety factor for females before and after walking on treated surfaces and analyzed under cryo-SEM the tarsal attachment devices of N. viridula and C. capitata after walking on treated surfaces. We observed contamination by the kaolin nanoflakes in both the smooth pads of the bug and the hairy pads of the fly. The present study can help to better understand the mechanism of action of kaolin particle film and can contribute to develop future physical control barriers against pest insects, particularly relevant owing to the need to reduce the negative impacts of pesticides on environment and human health.

Female competition for availability of males in insects: the Nezara viridula (Linnaeus, 1758) model.

Multimodal communication in solitary stinkbugs enables them to meet, mate and copulate. Many plant-dwelling species exchange information during the calling phase of mating behavior using substrate-borne vibratory signals. A female-biased gender ratio induces rivalry and competition for a sexual partner. Female competition for males, first described among Heteroptera in three stinkbug species, revealed species specific differences and opened the question of plasticity in individually emitted temporal and frequency signal characteristics during calling and rival alternation. To address this question and gain an insight into the mechanisms underlying stinkbug female rivalry, we compared the characteristics of alternated signals in the southern green stinkbug Nezara viridula (Linnaeus, 1758) (Hemiptera: Pentatomidae). Compared to male rivalry, female rivalry is more complex, lasts longer and runs through successive phases by a combination of different song types. The male pheromone triggers alternation between females, producing song pulses that occasionally overlap each other. One female initiates the rivalry by changing individual pulses into pulse trains of three different types. The competing female alternates with pulses of changed temporal characteristics at lower levels of rivalry and by varying the frequency characteristics of pulse trains at higher levels. During female rivalry, the male either stops responding or occasionally emits calling and courtship signals in response to the female that has produced signals of steady temporal characteristics. Female rivalry shows complex and species specific patterns of information exchange at different levels with a broad-range variation of temporal and frequency characteristics of, until now, unidentified vibratory emissions.

Candidate genes coding for odorant binding proteins and chemosensory proteins identified from dissected antennae and mouthparts of the southern green stink bug Nezara viridula

The southern green stink bug Nezara viridula (Hemiptera: Pentatomidae) is a highly polyphagous pest that can significantly impact many major crops worldwide. Insect odorant binding proteins (OBPs) and chemosensory proteins (CSPs) transport chemicals and play critical roles in chemoreception. Studies on N. viridula OBPs and CSPs should increase our overall understandings on chemosensory systems and chemical ecology of stink bugs, which may lead to improved pest control. In this study, we identified candidate genes encoding putative OBPs and CSPs in N. viridula by generating transcriptomes from dissected antennae and mouthparts. In total, the 42 unigenes were identified coding for OBPs (34 Classic OBPs and eight Plus-C OBPs) and 13 unigenes coding for CSPs. Expression profiles of OBP- and CSP -encoding genes were compared between antennae and mouthparts based on FKPM values. Candidates for antenna-predominant OBPs and CSPs were selected for real-time quantitative PCR analyses. Analyses of tissue expression profiles revealed that 17 OBP-encoding genes, and four CSP genes were primarily expressed in antennae, suggesting their putative roles in perception of volatiles. The sex-biased expression patterns of these antenna-predominant genes suggested that they may have important functions in reproduction of the insect. This is a systematic analysis on OBPs and CSPs in a stink bug, providing a comprehensive resource for future functional studies not only for N. viridula, but also for other stink bugs as well.

Structure and biomechanics of the antennal grooming mechanism in the southern green stink bug Nezara viridula

Insects devote a large amount of time to self-groom to remove foreign material, especially from their sensory appendages. Using various microscopy techniques and behavioural experiments on intact and ablated insects, the present study investigates the antennal grooming of the southern green stinkbug Nezara viridula, which represents a serious pest of different crops in most areas of the world. The antennal grooming behaviour encompasses an action of scraping involving the tibial comb complex (tibial comb + fossula) of both forelegs, generally followed by the tibial comb complex grooming of one leg using the tarsal hairy adhesive pad of the opposite leg (rubbing). From our observations, we can exclude a role in the antennal grooming of other structures such as the foretibial apparatus, while we show an involvement of this last structure in repositioning the stylets inside the labium. The external and internal morphology (cryo-scanning and transmission electron microscopy) and the evidence for the presence of large proportions of the elastic protein resilin (confocal laser scanning microscopy) in some parts of both the tibial comb complex and the foretibial apparatus are shown, and their functional roles are discussed. For the first time we demonstrated here the multipurpose role of the basitarsal hairy adhesive pad that is involved in both antennal grooming and adhesion to the substrate.

Contrasting olfactory responses of two egg parasitoids to buckwheat floral scent are reflected in field parasitism rates

Conservation biological control programs advocate the planting of flower strips alongside crops to improve the survival and effectiveness of parasitoids. Ideally, the provided food plants are highly attractive and benefit the targeted biocontrol agents without promoting pests or intraguild competition. Previous laboratory studies showed that Trissolcus basalis, an egg parasitoid of the stink bug Nezara viridula, is highly attracted to floral odors of buckwheat and that its nectar increases the wasp’s fecundity. In the field, T. basalis competes with the co-occurring parasitoid Ooencyrtus telenomicida for host eggs. Therefore, in the present study, we explored whether O. telenomicida shows similar attraction to buckwheat volatiles. We then carried out a 2-year field experiment to assess whether the laboratory-observed olfactory behaviors of both species are reflected in changed parasitism rates of stink bug eggs. Parasitism by naturally occurring egg parasitoids was measured in tomato plots with and without a margin of flowering buckwheat. Our results showed that, unlike T. basalis, O. telenomicida was repelled by the odor of buckwheat flowers. In both years, T. basalis found more egg batches and parasitized more stinkbug eggs when flower margins were present. Egg parasitism correlated positively with proximity to the buckwheat margin. In accordance with our prediction, egg parasitism by O. telenomicida occurred almost exclusively in the control plots and for a shorter period during the season. We conclude that buckwheat strips can influence intraguild competition and hypothesize that the effect was mediated by floral volatiles.

Effect of Certain Weather Factors and Some Natural Enemies on The Population Densities of Four Piercing-Sucking Insects on The Cotton Crop at Kafr El-Sheikh Governorate

The effect of prevailing weather factors (mean daily of temperature, relative humidity and wind speed) and some natural enemies (six insect predators were recorded; Coccinella undecimpunctata, L.; Scymnus interruptus Goez.; Paederus alfierii Koch, Syrphus spp., Orius spp. and Chrysoperlla carnea (Steph.) on the population densities of the cotton aphid (Aphis gossypii Glover), whitefly (Bemisia tabaci (Genn.), Jassids (Empoasca spp.) and green stink bug (Nezara viridula (L.)), during 2016 to 2017 cotton growing seasons was studied at the Farm of Sakha Agricultural Research Station, Kafr El-Sheikh Governorate. Results revealed that: 1. The initial infestation cotton aphid on cotton plants appeared in the second week of July of 2016 and 2017 seasons (12th and 11th of July of the two seasons, respectively) and had three peaks of population activity of both seasons of the long period of 12th of July till the 20th of September of the first season, and 11th of July till the 26th of September of the second season. The aphid population density was affected positive significantly (0.498*) in the first season and unsignificantly (0.310) in the second season by the temperature. Whereas, the relative humidity was affected positive unsignificantly in both seasons (0.375 and 0.320), respectively, but the effect by the wind speed was negative and highly significant in the two seasons 2016 and 2017 (-0.582** and 0.710**), respectively. The effect by the insect predators on the population density of A. gossypii were positive and highly significant correlations recorded in both seasons were (0.587** and 0.620**), respectively. 2. The cotton whitefly began to appear on cotton leaves at 28th of June of both seasons and had four peaks of population activity of both seasons, of the long period of 28th of June till the 4th of October in the first season and 28th of June till the end of the second season (24th of October). The whitefly population density was affected positive highly significant (0.727**) in the first season, and unsignificantly (0.383) in the second season by the temperature. Whereas, the relative humidity was affected positive unsignificantly (0.378) in the first season and significant (0.490*) in the second season, but the affected by the wind speed was unsignificantly positive and negative (0.090 and -0.280) in the 2016 and 2017 seasons, respectively. The effect by the insect predators on the population density of B. tabaci were positive and significant correlations recorded in both seasons were (0.505* and 0.470*), respectively. 3. The cotton jassids began to appear on cotton leaves at 30th of May and 6th of June in the two seasons, respectively, and had five peaks of population activity in 2016 season of the long period of 30th of May till the 27th of September and six peaks in 2017 season of the long period of 6th of June till the end of the season (24th of October). The relationship between the temperature and the population density of this insect was positive and highly significant (0.713**) in the first season, and unsignificant (0.420) in the second season. So, the effect by the relative humidity on the population density of jassids was positive and unsignificant (0.221 and 0.400) in both seasons, respectively. While, the wind speed was positively insignificantly and negatively significantly (0.298 and -0.490*) with insect numbers in 2016 and 2017 seasons, respectively. While the effect by the insect predators on the population density of Empoasca spp. were positive and significant correlations recorded in both seasons were (0.485* and 0.510*), respectively. 4. The green stink bug began to appear on cotton leaves at 14th and 13th of June in the 2016 and 2017 seasons, respectively, and had three peaks of both seasons of the long period of 14th of June till 18th of October in the first season and 13th of June till 17th of October of the second season. The population density of this insect on cotton plants was affected negatively and unsignificantly (-0.086 and 0.180) in both seasons by the temperature, respectively. But, the relative humidity had unsignificantly positive and negative (0.021 and -0.060) in both seasons, respectively. While, the effect of the wind speed was negative and unsignificantly (-0.237 and -0.080) in both seasons, respectively. The population density of N. viridula on cotton plants was affected by the insect predators were positive and significant correlations recorded in both seasons were (0.515* and 0.499*), respectively. Study the effect of abiotic and naturally occurring biotic factors on seasonal population fluctuations of insect pests, this factors to played the main factor in the evolution and distribution of this insect pest.

Attachment ability of the polyphagous bug Nezara viridula (Heteroptera: Pentatomidae) to different host plant surfaces

The present investigation tests through friction experiments the attachment ability of adults of the southern green stink bug Nezara viridula L. (Heteroptera: Pentatomidae), a polyphagous insect representing a cosmopolitan pest, on different host plant species characterized by smooth, hairy and waxy surfaces. Surfaces of different tested plants have been studied in Cryo-Scanning Electron Microscope (Cryo-SEM). The load cell force transducer was used to evaluate the potential damage to the insect attachment devices induced by walking on the different leaf surfaces. In case of the plant Phaseolus vulgaris, where insects showed a strong reduction in their adhesion ability during and after walking on the leaf, the damage to the insect by two cultivars with different morphological features and the insect ability to recover after 24 h has been evaluated. The ability to recover notwithstanding the damage to attachment devices, shown by Cryo-SEM investigations, together with the strong attachment forces produced on various plant leaves, characterized by different morphological features, is in agreement with the great adaptability and ecological plasticity of this widely-spread bug species. The present study, increasing our knowledge on the mechanical interaction of this species with different host plant species, can help to develop new strategies to control this insect pest.

Contribution of different tarsal attachment devices to the overall attachment ability of the stink bug Nezara viridula.

The tarsal attachment devices of the southern green stink bug Nezara viridula, a cosmopolitan pest of different crops, encompass a pair of claws, distal pretarsal smooth pulvilli, and a proximal hairy pad on the ventral basitarsus. To evaluate the role of these attachment devices in generating attachment, behavioural experiments testing locomotion of insects with ablated pulvilli, shaved hairs and cut-off claws were performed. Using traction force experiments, insect attachment performance was evaluated on artificial substrates characterised by different roughness and on two substrates with different surface energies in the air and under water. To examine the contact area of attachment devices during resting, pulling and inverted walking, intact insects and those without claws were video-recorded using a high-speed camera. The present data reveal a great involvement of pulvilli in insect attachment on all the tested surfaces, while the hairy pad seems to have a role in producing friction forces only on smooth surfaces and on surfaces with intermediate roughness. The hairy pad was revealed to be important in adhesion to hydrophobic substrates under water, a function that could be relevant for N. viridula insects in consideration that many plant leaves tend to have hydrophobic surfaces and may be often covered by water film.

On the spot: utilization of directional cues in vibrational communication of a stink bug

Although vibrational signalling is among the most ancient and common forms of communication, many fundamental aspects of this communication channel are still poorly understood. Here, we studied mechanisms underlying orientation towards the source of vibrational signals in the stink bug Nezara viridula (Hemiptera, Pentatomidae), where female vibrational song enables male to locate her on the bean plant. At the junction between the main stem and the leaf stalks, male placed his legs on different sides of the branching and orientation at the branching point was not random. Analyses of signal transmission revealed that only a time delay between the arrival of vibrational wave to receptors located in the legs stretched across the branching was a reliable directional cue underlying orientation, since, unexpectedly, the signal amplitude at the branching point was often higher on the stalk away from the female. The plant and the position of the vibrational source on the plant were the most important factors influencing the unpredictability of the amplitude cue. Determined time delays as short as 0.5 ms resulted in marked changes in interneuron activity and the decision model suggests that the behavioural threshold is in the range between 0.3 and 0.5 ms.

Stink bug nezara viridula sustains late MAPKs phosphorylation status and induces expression of genes related with cell wall rearrangement in developing soybean seeds

The southern green stink bug (Nezara viridula) is a serious invasive pest in United States and South America that decreases the quantity and quality of soybean seeds. Plants respond to insect attack recognizing cell injury and oral secretions, triggering mitogen-activated protein kinases (MAPK) pathway and inducing defenses against herbivores. Our field studies were conducted to evaluate late MAPKs involvement in defense modulation and the transcriptional response of soybean genes implicated in cell wall modification after stink bugs fed on developing seeds. We observed an induction in MPK3 and MPK6 transcription at 24 and 72 h after insects attacked soybean pods, while MPK6 was the only gene up-regulated after mechanically damaging the seeds. Exposure to JA and SA stimuli increased MPK3 and MPK6 levels. While SA triggered MPK4 activation, MPK3 and MPK6 were phosphorylated after both JA and SA treatments. Stink bugs feeding and SA treatment specifically increased the expression of expansine (EXP), xyloglucan endo-transferase (EXT), pectate lyase (PL), and polygalacturonase (PG) genes, all involved in the relaxation and restructuration of the cell wall. Moreover, examination of safranin-stained seed sections revealed that stink bug damage resulted in thickening of cell walls even on distal undamaged areas of cotyledons. Our study shows that stink bug damage elicits activation of MAPK signal in soybean seeds and induced SA that may induce genes related with cell wall restructuration, and could increase resistance to new insect attack by hardening cell walls.