Adelphocoris Suturalis Research Articles

A transgenic strategy for controlling plant bugs (Adelphocoris suturalis) through expression of double-stranded RNA homologous to fatty acyl-coenzyme A reductase in cotton.

Plant bugs (Miridae species), which are sap-sucking insects, have emerged as major pests of cotton in China. Most Miridae species are not sensitive to commercial Bacillus thuringiensis (Bt) cotton, resulting in significant economic losses and an increased application of insecticide, which eventually may compromise the future of Bt cotton. We demonstrate that FATTY ACYL-COA REDUCTASE (AsFAR) plays an essential role in the reproduction of the bug Adelphocoris suturalis. Down-regulation of AsFAR expression by injection of double-stranded RNA suppresses ovarian development and female fertility, resulting in females producing few viable offspring. To determine the viability of an RNA interference approach to limit FAR expression and reproductive ability in A.suturalis, a dsRNA targeting the AsFAR gene (dsAsFAR) of A.suturalis was expressed in transgenic cotton plants. AsFAR transcription levels were significantly downregulated in A.suturalis feeding on the transgenic plants. In contained field trials, the transgenic cotton lines significantly suppressed the development of A.suturalis populations and were resistant to damage caused by plant bug infestation. These results suggest a new strategy for the management of plant bug pests of cotton.

The genome sequence of a novel RNA virus in Adelphocoris suturalis.

The complete genome of a novel virus found in Adelphocoris suturalis was determined by RNA-seq and named Adelphocoris suturalis-associated virus 1 (ASV1). ASV1 has a single-stranded RNA genome of 10,845 nucleotides in length and contains five putative open reading frames (ORFs). ORF1 encodes a polypeptide of 2592 amino acids (aa) and contains four conserved domains: a viral RNA methyltransferase domain, an FtsJ-like methyltransferase domain, a viral RNA helicase domain and an RNA-dependent RNA polymerase domain. ORF2, ORF3, ORF4 and ORF5 encode polypeptides of 190, 461, 103 and 159 aa, respectively, of which only ORF5 contains a conserved domain, the Tobacco mosaic virus-coat superfamily. Phylogenetic analysis with the deduced amino acid sequences indicated that ASV1 clusters with the Drosophila-related Boutonnet virus. The similar genomic structure and high bootstrap value identified in the maximum-likelihood tree suggest that ASV1 (possibly alongside Boutonnet virus) could be considered the prototype of a new taxon of unclassified insect viruses. The prevalence of ASV1 infection in wild populations of A. suturalis was at a low level (6.60%, 14 positives from 212 samples).

Odorant-binding and chemosensory proteins identified in the antennal transcriptome of Adelphocoris suturalis Jakovlev

Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) is an insect pest that causes severe agricultural damage to cotton and many other important crops. In insects, olfaction is very important throughout their lifetime. There are two groups of small soluble proteins, named odorant binding proteins (OBPs) and chemosensory proteins (CSPs), which are suggested to participate in the initial biochemical recognition steps of insect olfactory signal transduction. In this study, a total of 16 OBPs (12 classical OBPs and 4 plus-C OBPs) and 8 CSPs, were identified in the antennal transcriptome of A. suturalis. The sex- and tissue-specific profiles of these binding protein genes showed that 13 of the 16 OBP transcripts were highly expressed in the antennae of both sexes, and 4 OBPs (AsutOBP1, 4, 5 and 9) were expressed higher in the male antennae compared to the female antennae. Three CSPs (AsutCSP1, 4 and 5) were expressed specifically in the antennae of both sexes, and AsutCSP1 was expressed higher in the male antennae than in the female antennae. Our findings identify several novel OBP and CSP genes for further investigation of the olfactory system of A. suturalis at the molecular level.

Identification and field verification of sex pheromone from the mirid bug, Adelphocoris suturalis

Numerous species of mirid bugs (Hemiptera: Miridae) are phytophagous insect pests that damage economically important field and horticultural crops. In recent years, Adelphocoris suturalis has become a significant pest in transgenic Bacillus thuringiensis (Bt) cotton fields. We previously reported that virgin A.suturalis females attracted males in the field. In this study, we found that A. suturalis males are not attracted in Y-tube olfactometer bioassays to odors from either live nymphs or sexually mature virgin females whose ostioles of the metathoracic scent gland (MTG) are occluded with paraffin wax. However, males are significantly attracted to odors from adult virgin females when female abdomina are occluded with paraffin, indicating that female A. suturalis release sex pheromones only from the MTG. Volatile extracts from both sexes were collected and analyzed by gas chromatography–electroantennogram detection and gas chromatography–mass spectrometry. We identified (E)-4-oxo-2-hexenal (E4O2H), hexyl hexanoate (HH) and hexyl butyrate (HB) as major components and found that they elicited the largest EAD responses from antennae of males. Both E4O2H and HH were present in aeration extracts from females, while E4O2H was found in males. Capture of only males in field tests using synthetic compounds confirmed the activity of the identified sex pheromone candidates. In the field tests, a 10:1 ratio of the E4O2H and HH binary blend exhibited the highest efficiency in attracting male A. suturalis. Addition of HB to the binary pheromone blend to make a ternary blend did not increase trap catches. These results demonstrate that E4O2H and HH constitute the A. suturalis sex pheromone components.

Phylogeographic structure of cotton pest Adelphocoris suturalis (Hemiptera: Miridae): strong subdivision in China inferred from mtDNA and rDNA ITS markers.

Phylogeographic patterns of some extant plant and vertebrate species have been well studied; however, they are poorly understood in the majority of insects. The study documents analysis of mitochondrial (COI, CYTB and ND5) and nuclear (5.8S rDNA, ITS2 and 28S rDNA) data from 419 individuals of Adelphocoris suturalis, which is one of the main cotton pests found in the 31 locations in China and Japan involved in the study. Results show that the species is highly differentiated between populations from central China and peripheral China regions. Analysis of molecular variance showed a high level of geographical differentiation at different hierarchical levels. Isolation-by-distance test showed no significant correlation between genetic distance and geographical distance among A. suturalis populations, which suggested gene flow is not restricted by distance. In seven peripheral populations, the high levels of genetic differentiation and the small Nem values implied that geographic barriers were more likely restrict gene flow. Neutrality tests and the Bayesian skyline plot suggested population expansion likely happened during the cooling transition between Last Interglacial and Last Glacial Maximum. All lines of evidence suggest that physical barriers, Pleistocene climatic oscillations and geographical heterogeneity have affected the population structure and distribution of this insect in China.

Morphology and chemical analysis of the metathoracic scent glands system in Adelphocoris suturalis (Hemiptera: Miridae).

The morphological structure of the metathoracic scent glands (MTGs) in Adelphocoris suturalis was observed by utilizing scanning electron microscope (SEM). Also, the secretions of MTGs in male and female were analyzed by using gas chromatography–mass spectrometry (GC-MS). The result showed that the MTGs comprised a reservoir and paired lateral glands, which are connected to a reservoir by duct. The MTGs belong to the diastomian type. A usually depressed channel extends from opening downward the middle of metathorax, a tongue-like structure was covered by bristles and mushroom-shaped cuticular structures, known as evaporative area. In GC-MS investigation, differences were found in quantitative or qualitative compositions of the substances between the two sexes. In our study, hexyl butyrate was the most abundant compound in the MTGs of A. suturalis , comprising ∼85% of total secretions in both female and male, respectively. 4-oxo-(E)-2-hexenal (5.22%) was the second most abundant compound in female MTGs secretions, whereas octacosane (2.42%) followed hexyl butyrate in male MTGs secretions.

Early-Season Host Switching in Adelphocoris spp. (Hemiptera: Miridae) of Differing Host Breadth

The mirid bugs Adelphocoris suturalis (Jakovlev), Adelphocoris lineolatus (Goeze) and Adelphocoris fasciaticollis (Reuter) (Hemiptera: Miridae) are common pests of several agricultural crops. These three species have vastly different geographical distributions, phenologies and abundances, all of which are linked to their reliance on local plants. Previous work has shown notable differences in Adelphocoris spp. host use for overwintering. In this study, we assessed the extent to which each of the Adelphocoris spp. relies on some of its major overwinter hosts for spring development. Over the course of four consecutive years (2009–2012), we conducted population surveys on 77 different plant species from 39 families. During the spring, A. fasciaticollis used the broadest range of hosts, as it was found on 35 plant species, followed by A. suturalis (15 species) and A. lineolatus (7 species). Abundances of the species greatly differed between host plants, with A. fasciaticollis reaching the highest abundance on Chinese date (Ziziphus jujuba Mill.), whereas both A. suturalis and A. lineolatus preferred alfalfa (Medicago sativa L.). The host breadths of the three Adelphocoris spp. differed greatly between subsequent spring and winter seasons. The generalist species exhibited the least host fidelity, with A. suturalis and A. lineolatus using 8 of 22 and 4 of 12 overwinter host species for spring development, respectively. By contrast, the comparative specialist A. fasciaticollis relied on 9 of its 11 overwinter plants as early-season hosts. We highlight important seasonal changes in host breadth and interspecific differences in the extent of host switching behavior between the winter and spring seasons. These findings benefit our understanding of the evolutionary interactions between mirid bugs and their host plants and can be used to guide early-season population management.

Diapause Induction in <I>Apolygus lucorum</I> and <I>Adelphocoris suturalis</I> (Hemiptera: Miridae) in Northern China

With widespread planting of Bt cotton and an associated reduction in the use of broad-spectrum insecticides, the mirid bugs Apolygus lucorum (Meyer-Dür) and Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) become major pests of cotton in northern China in recent years. Both species overwinter as diapausing eggs that may enhance ability to survive the cold winter. The effects of photoperiod and temperature on diapause induction in A. lucorum and A. suturalis were investigated under laboratory conditions. Egg diapause was induced primarily by short photoperiod. Temperatures ranging between 17 and 26°C had little effect on diapause induction for both species. The impact of photoperiod (x) on diapause incidence (y) was described with modified Michaelis-Menten models y = 1.1(14 - x)/(14.82 - x) for A. lucorum and y = 1.07(14 - x)/(14.79 - x) for A. suturalis. The critical photoperiod for diapause induction in the first instars of parental A. lucorum and A. suturalis calculated from the models above was almost identical, at 13.3 h (13 h, 18 min) in a 24-h cycle. The parental nymphal stage was sensitive to short photoperiod for diapause induction in both species, with the first-instar nymphs the most sensitive. The sensitivity to short photoperiod decreased gradually as the A. suturalis nymphs developed, whereas the sensitivity dropped sharply at the second instar of A. lucorum. The adults of both species exhibited little sensitivity to photoperiod for diapause induction.

Comparative overwintering host range of three Adelphocoris species (Hemiptera: Miridae) in northern China

In northern China, Adelphocoris suturalis, Adelphocoris lineolatus and Adelphocoris fasciaticollis (Hemiptera: Miridae) are common pests of cotton and several other crops. These species have vastly diverse geographic distribution, seasonal dynamics and abundance, the underlying causal factors of which are poorly understood. In this study, the importance of a broad range of plant species as overwintering hosts for each Adelphocoris sp. was compared. Nymphal emergence from a total of 126 plant species was monitored at two distinct locations. The eggs of A. suturalis successfully eclosed from un-plowed cotton field soil and 115 plant species, primarily pastures, weeds and agricultural crops. The eggs of A. lineolatus successfully eclosed from 40 plant species, mainly pastures and weeds. Finally, A. fasciaticollis overwintered on 35 plant species, primarily tree species, weeds and agricultural crops. In conclusion, the most common and widely distributed mirid species, A. suturalis, overwintered on a comparatively broader range of plants compared to the other two species. These observations help to understand the differences in geographical distribution and abundance of the three Adelphocoris species, and constitute the basis for forecasting and pest management protocols for Adelphocoris spp. in China.

Evidence of Female-Produced Sex Pheromone of Adelphocoris suturalis (Hemiptera: Miridae): Effect of Age and Time of Day

After the reduction in the use of broad-spectrum insecticides, Adelphocoris suturalis (Hemiptera: Miridae) has become an important pest of transgenic cotton, Gossypium hirsutum L., in China. A. suturalis is a highly mobile insect, moving rapidly in and out of crop fields, and traps baited with sex pheromones may be useful in monitoring and controlling its numbers. However, little is currently known regarding the chemical communication based on sex pheromones by this species. To use the synthesized sex pheromone effectively as part of the integrated pest management, some fundamental biological parameters under which the pheromone is produced must be understood. In this study, attractiveness of adult females or males of A. suturalis to conspecific individuals was examined by Y-tube bioassay; we also investigated the female sexually mature age and circadian rhythm of male attraction to females of A. suturalis in the field in 2008 and 2010. Y-tube bioassay results indicated that only males were attracted to odors from sexually mature virgin females. Two-year field trapping experiments showed that 4-18-d-old virgin females effectively attracted males, and males were attracted to virgin females during the scotophase, with a peak between 1900 and 2300 hours. These results improve our understanding of the sexual communication behavior of A. suturalis and provide evidence of female-produced sex pheromone in this species.

헤어리베치에서 톱다리개미허리노린재 발생양상 및 기주에 따른 발육 및 선호성

충남 아산의 보리와 헤어리베치가 혼작된 포장과 대전 유성의 헤어리베치 포장에서 5월 중순부터 채종 후인 7월 중순까지 집합페로몬트랩을 이용해 유인된 톱다리개미허리노린재의 발생양상을 조사한 결과, 종자의 결실이 이루어지는 6월 하순부터 포장내로 유입되어 들어오는 개체수가 증가하기 시작하였으나 7월 중순 채종작업이 끝나면서 유입개체가 감소하는 경향을 보였으며, 이후에도 11월 초까지 계속적으로 유인되는 것이 확인되었다. 헤어리베치 포장에서는 톱다리개미허리노린재 외에도 닮은수염노린재, 알락수염노린재, 변색장님노린재, 실노린재를 포함한 총 33종의 노린재목 곤충이 채집되어 많은 종류의 노린재류들이 서식하고 있음을 알 수 있었다. 실내에서는 헤어리베치를 먹이로 제공하였을 경우에는 정상적인 발육이 이루어지지 않았으며, 4령 약충 이후부터 생존율이 감소하고 성충으로의 우화가 이루어지지 않았으며, 먹이 선호성에 있어서도 헤어리베치보다는 콩을 더 선호하는 것으로 나타났다. 결과적으로 헤어리베치는 톱다리개미허리노린재가 정상적인 발육을 하면서 개체군을 발달시키기에 적합한 기주식물로 판단되지 않으며, 종자결실기에 맞춰 종자를 흡즙하기 위한 방문서식처로서 작용할 가능성이 높은 것으로 판단되었다. The seasonal occurrence of Riptortus pedestris Fabricius was investigated using pheromone traps baited with its aggregation pheromone in the fields with various crop composition (mixture culture of barley and hairy vetch in Asan, Chungnam; monoculture of hairy vetch in Yuseung, Daejeon) from mid-May to mid-July of seed gathering season in 2010. The invasion of R. pedestris into the experimental fields began to increase rapidly from late-June in which period hairy vetch and barley reach the beginning of seed formation stage. After seed gathering season in mid-July, the invasion rate of R. pedestris decreased, and the activity was continually observed till early-November. In addition to dominant R. pedestris species, 33 species of hemiptera including Apolyaus watajii, Dolycoris baccarum, Adelphocoris suturalis, and Yemma exlis were collected, which indicated abundant species diversity in the hairy vetch fields. In the laboratory, R. pedestris did not developed successfully to adult stage on food sources of hairy vetch, with decreasing survival rate after 4th instar and the failure of emergence to adult stage. Also, R. pedestris showed higher preference on soybeans than hairy vetch. Consequently, hairy vetch may be not true host for the development and survival of R. pedestris. It is considered that R. pedestris is a temporary visitor at the season of seed formation in hairy vetch fields.

Effects of Transgenic Bt Cotton on the Population Density, Oviposition Behavior, Development, and Reproduction of a Nontarget Pest, <I>Adelphocoris suturalis</I> (Hemiptera: Miridae)

Transgenic cotton has shown great promise for the control of target pest insects; however, frequent outbreaks of nontarget pest mirids has been recorded in recent years in northern China. To test the hypothesis that transgenic cotton contributes to nontarget pest outbreaks, we studied the impact of transgenic Bt cottons (both Bt and Bt + CpTI) on the fitness of nontarget pest Adelphocoris suturalis Jakovlev. No significant differences were detected between population densities of A. suturalis in unsprayed nontransgenic cottons and in unsprayed transgenic Bt cottons in 2007, 2008, and 2009. No difference in preferred oviposition site or egg production was detected between transgenic and nontransgenic cottons in both free choice and no choice tests. No difference in life table parameters was detected for A. suturalis between Bt cottons and nontransgenic cottons. All these results indicated that transgenic crops did not contribute to the nontarget pest outbreaks when being compared with their parental lines. The possible reasons for intensified pest status of A. suturalis, such as decrease of pesticide application, deficient natural enemies, and area-wide shift of cotton varieties, were discussed.

Comparative study of temperature‐dependent life histories of three economically important Adelphocoris spp.

Abstract.Subsequent to the widespread adoption of Bt transgenic cotton in China and an associated reduction in pesticide use, Adelphocoris spp. (Hemiptera: Miridae) are the key pests of this crop. Three species (Adelphocoris suturalis, Adelphocoris fasciaticollis and Adelphocoris lineolatus) are found in Chinese Bt cotton fields, each with a distinct geographic distribution and phenology. In the present study, the development and fecundity of the three species are compared in the laboratory at various temperatures in the range 10–35 °C. Although nymphal development and adult moulting occurs under all temperature regimes, egg eclosion is not observed at 10 °C. In general, egg and nymphal development periods decrease with increasing temperature up to 30 °C. The lower and upper development thresholds are, respectively, 5.6 and 40.1 °C for A. suturalis eggs; 5.0 and 38.4 °C for nymphs; 6.3 and 39.0 °C for A. fasciaticollis eggs, 3.0 and 41.9 °C for nymphs; 5.6 and 41.3 °C for A. lineolatus eggs; and 6.2 and 38.8 °C for nymphs. Thermal constants are 189.9 degree days (DD) (egg) and 308.8 DD (nymph) for A. suturalis, 188.8 DD (egg) and 366.7 DD (nymph) for A. fasciaticollis, and 231.7 DD (egg) and 291.6 DD (nymph) for A. lineolatus. Temperatures above 30 °C affect egg development of A. fasciaticollis and A. lineolatus adversely, but not that of A. suturalis. At the same time, nymphal survival of A. suturalis is reduced at 10 °C. Longevity of all species declines with increasing temperature, whereas extremes of temperature (i.e. 10 and 35 °C) interfere with oviposition. The estimated optimum range for oviposition is 23–25 °C, irrespective of species. In general, development and fecundity of the three Adelphocoris spp. is consistent with their respective distribution and seasonal dynamics. The present study provides insight into the distribution and phenology of Adelphocoris spp., and contributes to the modelling of their population dynamics.

Species composition and seasonal abundance of pestiferous plant bugs (Hemiptera: Miridae) on Bt Cotton in China

Only recently, due to a major reduction of broad-spectrum insecticide use in transgenic (Bt) cotton in China, plant bugs (Heteroptera: Miridae) have emerged as key pests of this crop. To determine their species composition and seasonal activity at various locations nationwide, field surveys were carried out between 2002 and 2006, using sweep-net samples and visual observation. Surveys were conducted in three major cotton-growing regions: Changjiang River, Yellow River, and Northwestern Region. The mirid complex on Bt cotton basically consisted of five different species, with Lygus lucorum, Lygus pratensis, and Adelphocoris suturalis most commonly encountered . L. lucorum and A. suturalis were the dominant species in the Changjiang River and Yellow River Region, while L. pratensis was the most common species in the Northwestern Region. The various mirid species were found in cotton fields throughout the cotton-growing season, usually with great population densities during the squaring and flowering stages. Peak mirid abundance ranged from 50 to 200 per hundred plants. Given the comparatively low economic thresholds for mirids (approx. 10 individuals/100 plants), these insects constitute serious pests in all cotton-growing regions of China. This paper suggests that L. lucorum, L. pratensis, and A. suturalis should be treated as the main targets for developing pestiferous mirid forecasting and management strategies, which would be defined at or prior to the flowering and squaring stages of cotton in China.

Plant growth-regulating factor in the salivary gland of several heteropterous insects

1. 1. Plant growth-regulating factor in the salivary gland was compared among several phytophagous bugs. 2. 2. In the absence of IAA, the growth of Avena coleoptiles was significantly accelerated by the salivary gland solution of Adelphocoris suturalis. 3. 3. In the presence of IAA, the growth of Avena coleoptiles was strongly promoted by the salivary gland solutions of Stenotus binotatus, Palomena angulosa, Carpocoris purpureipennis and Coreus marginatus orientalis with a significance at 5% level. 4. 4. The extract from the fraction III of the salivary gland solutions of Lygus saundersi, Orthocephalus funestus and P. angulosa significantly accelerated the growth of Avena coleoptiles, exceeding that of the IAA control. 5. 5. Almost all the bugs used seem to have auxin and/or factor indirectly promoting plant growth (IGPF) in their salivary gland. 6. 6. The relationship between the presence of plant growth-promoting factor in the salivary gland and the phytopathogenicity of heteropterous insects is discussed.