EPG waveform characteristics of solenopsis mealybug stylet penetration on cotton

The solenopsis mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), is a polyphagous insect known to cause severe damage to cotton (especially transgenic varieties) in South Asia, and currently poses a serious threat in Asia and potentially elsewhere. Stylet penetration behavior of P. solenopsis on cotton was monitored using the electrical penetration graph (EPG) technique (DC system) and the EPG characteristics were compared with those previously published from Phenacoccus manihoti Matile‐Ferrero and Planococcus citri (Risso). We identified and further characterized typical waveforms of A, B, C, and pd (together pathway), E1 and E2 (phloem), F (derailed stylet mechanics), and G (xylem). Five novel EPG aspects were distinguished in the EPG waveforms from P. solenopsis: (1) obvious B waveforms occurred following waveform A, (2) during waveform C, some aphid‐like E1e waveforms were observed, (3) prolonged potential drops (pd) up to >1 h occurred with two continuously alternating sub‐phases pd1 and pd2, (4) the pd1 waveform always occurred as the first waveform related to phloem sieve elements, preceding the other phloem waveforms (E), the labeling of which we changed to achieve a better comparison to the aphid E waveforms, and (5) waveform F, related to derailed stylet mechanics occurred but was not reported from other mealybugs so far. This is mainly a waveform morphology study to extend existing knowledge on mealybug EPGs to investigate mealybug‐host plant interactions. Further experimental verification of waveform correlations with plant tissue positions of stylet tips and insect activities is still needed.     

Comparison of Phenacoccus solenopsis specimens from different regions of Pakistan using COI molecular barcoding (Hemiptera: Pseudococcidae)

Because correct identification of insects is crucial for pest management involving chemical or biological control agents, we have used a molecular approach to identify and characterize specimens of the cotton pest Phenacoccus solenopsis Tinsley (Sternorrhyncha: Pseudococcidae) present in different regions of Pakistan. The specimens were analyzed through DNA sequence analysis of their mitochondrial COI (mtCOI) gene using an improved procedure that could distinguish between the pest and its associated parasitoid. Our analysis showed no variation among the mealybug specimens from different geographical locations of Pakistan and confirmed that this is the same species and haplotype that is infesting cotton plants in other parts of Asia. This information will assist in the development of biological control programs against P. solenopsis in Pakistan and other Asian countries.     

Effects of the invasive plant Eupatorium adenophorum on the exotic mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae) and their natural enemies

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The Cassava Mealybug (Phenacoccus manihoti) in Asia: First Records,Potential Distribution,and an Identification Key

Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), one of the most serious pests of cassava worldwide, has recently reached Asia, raising significant concern over its potential spread throughout the region. To support management decisions, this article reports recent distribution records, and estimates the climatic suitability for its regional spread using a CLIMEX distribution model. The article also presents a taxonomic key that separates P. manihoti from all other mealybug species associated with the genus Manihot. Model predictions suggest P. manihoti imposes an important, yet differential, threat to cassava production in Asia. Predicted risk is most acute in the southern end of Karnataka in India, the eastern end of the Ninh Thuan province in Vietnam, and in most of West Timor in Indonesia. The model also suggests P. manihoti is likely to be limited by cold stress across Vietnam''s northern regions and in the entire Guangxi province in China, and by high rainfall across the wet tropics in Indonesia and the Philippines. Predictions should be particularly important to guide management decisions for high risk areas where P. manihoti is absent (e.g., India), or where it has established but populations remain small and localized (e.g., South Vietnam). Results from this article should help decision-makers assess site-specific risk of invasion, and develop proportional prevention and surveillance programs for early detection and rapid response.     

寄主植物对扶桑绵粉蚧体型及体内能源物质含量的影响

【目的】研究寄主植物对扶桑绵粉蚧雌成虫体型和体内能源物质含量的影响,为扶桑绵粉蚧的寄主适应性和风险分析提供科学参考。【方法】在室内用8种寄主植物连续饲养扶桑绵粉蚧5代后,测量7日龄雌成虫体长、体宽和体重,并测定体内能源物质(脂肪、可溶性蛋白质、可溶性糖)含量,分析上述指标在不同寄主间的差异。【结果】取食不同寄主后,扶桑绵粉蚧雌成虫体型和体内能源物质含量存在显著差异。取食马铃薯后,雌成虫体长达4.80 mm,体宽为3.07 mm,单头体重为7.11 mg,显著高于取食其他寄主的雌成虫。取食棉花(Bt棉和常规棉)后,扶桑绵粉蚧雌成虫体内可溶性蛋白质含量最高(58.77和57.70 mg·g~(-1));取食常规棉后,可溶性糖含量最高(75.02 mg·g~(-1));取食马铃薯后,脂肪含量最高(349.00 mg·g~(-1))。【结论】寄主植物对扶桑绵粉蚧雌成虫体型和体内能源物质含量有显著影响。取食马铃薯后,扶桑绵粉蚧雌成虫体型较大,体内能源物质含量较高,因此应加强马铃薯上扶桑绵粉蚧的种群监测。     

杭州地区扶桑绵粉蚧危害调查及系统进化分析

【背景】扶桑绵粉蚧是近年来入侵我国的重要检疫性害虫,在我国多个省份均有发生,造成了严重的经济损失。【方法】于2009—2015年对杭州地区扶桑绵粉蚧的发生危害情况进行了实地调查,同时结合mt DNA COI分子标记方法,对扶桑绵粉蚧进行分子鉴定和系统进化分析。【结果】杭州市余杭区、萧山区和临安市3个地区发现扶桑绵粉蚧分布,共调查到寄主植物38科61属68种,以辣椒、茄子、番茄、南瓜、棉花、芝麻、菊花、苦荬菜、大花马齿苋和五色梅受害最严重。系统进化分析表明,杭州地区的扶桑绵粉蚧未发生明显的遗传分化,与我国其他地区扶桑绵粉蚧mt DNA COI基因相似度为99.4%~100%。【结论与意义】本研究为进一步研究扶桑绵粉蚧的遗传进化、可能的侵入途径以及科学防控提供了理论基础。     

Comparative development and reproduction of Planococcus ficus and Planococcus citri (Hemiptera: Pseudococcidae) on grapevine under field conditions

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Potential distribution and environmental threat of <Emphasis Type="Italic">Pueraria lobata</Emphasis>

Pueraria lobata (kudzu) is an invasive weed originating from East Asia. Local infestations have been recently observed in Switzerland and northern Italy; however, the potential for P. lobata to spread and to become abundant and damaging in the Alpine countries is not known. The aim of this study was to project the potential distribution of P. lobata under current climate in Switzerland, Austria and Slovenia and parts of northern Italy using the ecoclimatic model CLIMEX. In addition, areas at risk were identified where P. lobata may occur as a strong and aggressive competitor. This was derived from the plants’ distribution and climatic requirements in the south-eastern United States where the heaviest infestations occur. Projections show that 60.84% of the total land area of northern Italy, followed by 47.08% of Slovenia, 21.01% of Austria and only 1.97% of Switzerland are climatically suitable. P. lobata may become a troublesome weed due to very favourable climatic conditions only in some parts of northern Italy and Slovenia. In climatically suitable areas, any occurrence of the plant should be carefully observed. In infested and highly climatically suitable areas, there is a need for strategic management to prevent further spread of P. lobata.     

Predation potential of <Emphasis Type="Italic">Rhynocoris marginatus</Emphasis> (Hemiptera: Reduviidae) against three mealybug species of agricultural importance

The predation potential of a generalist predator Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) against three important mealybug pests of cotton, Phenacoccus solenopsis Tinsley, Maconellicoccus hirsutus Green, and Coccidohystrix insolita Green (Hemiptera: Pseudococcidae) was evaluated under laboratory conditions. The specific objective of the study was to determine the prey capturing time, prey handling time, and prey preference among the three mealybug species for different developmental stages of R. marginatus. The number of prey consumed/predator/24 h by R. marginatus was dependent on the mealybug species and the predator developmental stage. Rhynocoris marginatus showed a decrease in prey capturing time and handling time as the predator grew older. After evaluating the prey stage preference, results indicated that the developmental stages of R. marginatus preferred adult mealybugs over the younger stages. In a choice-test bioassay including the three mealybug species, no significant difference in prey species selection was observed for the various R. marginatus developmental stages. However, the mortality of P. solenopsis was observed to be highest among the mealybugs, followed by M. hirsutus and C. insolita. This supports the idea that R. marginatus can be effectively utilized for the management of one of the most destructive mealybug pests of cotton, P. solenopsis. Results from this study are important for the development of a knowledge-based management program for cotton agroecosystems affected by various mealybug pests.     

Report of a parasitic wasp (Hymenoptera: Encyrtidae) parasitizing cotton mealybug (Hemiptera: Pseudococcidae) in Pakistan and use of PCR for estimating parasitism levels

A parasitic wasp, Aenasius bambawalei, was studied for its biological parameters and parasitism levels in the cotton mealybug (Phenacoccus solenopsis). Biological parameters including parasitism efficiency, time to pupation, time to eclosion and adult sex ratio were studied under lab conditions. Parasitism levels in field collected mealybug were determined using PCR. Results showed an increase in parasitism over the study period, with higher parasitism levels in 2009 compared to the preceding 2 years.     

Analysis of expressed sequence tags (ESTs) from a normalized cDNA library and isolation of EST simple sequence repeats from the invasive cotton mealybug Phenacoccus solenopsis

The cotton mealybug, Phenacoccus solenopsis Tinsley, is a serious and invasive pest. At present, genetic resources for studying P. solenopsis are limited, and this negatively affects genetic research on the organism and, consequently, translational work to improve management of this pest. In the present study, expressed sequence tags (ESTs) were analyzed from a normalized complementary DNA library of P. solenopsis. In addition, EST‐derived microsatellite loci (also known as simple sequence repeats or SSRs) were isolated and characterized. A total of 1107 high‐quality ESTs were acquired from the library. Clustering and assembly analysis resulted in 785 unigenes, which were classified functionally into 23 categories according to the Gene Ontology database. Seven EST‐based SSR markers were developed in this study and are expected to be useful in characterizing how this invasive species was introduced, as well as providing insights into its genetic microevolution.     

Does the host plant affect the benefits from mutualisms? The invasive mealybug and ghost ant association

1. The benefits to trophobionte hemipterans are affected by the ant tending level, which is a widely accepted statement. The ant tending level is closely related to multiple factors. It is clear that the ant tending level can be affected by the temporal factor, age‐specific, the density of the hemipterans, and quantity and quality of honeydew produced by hemipterans. 2. Few studies of ant–hemipteran mutualisms have reported the patterns of host plants‐dependent effects, and whether host plants influence the ant tending level that is also unclear. As such, laboratory experiments were conducted to test whether the colony growth rate of an invasive mealybug Phenacoccus solenopsis Tinsley, parasitism of Aenasius bambawalei Hayat, an dominant parasitoid of P. solenopsis, are affected by tending by ghost ants (Tapinoma melanocephalum(Fabricius)], host plants (tomato and cotton), and interactions between the two factors. The difference in the ant tending level between the host plants was also determined. 3. The results showed that mealybug colony growth and parasitism were significantly affected by ant tending and host plant separately. There were significant interactions between the independent factors on the mealybug colony growth rate and percentage parasitism. These results suggest that benefits to mealybugs are host plant‐dependent.     

基于CLIMEX的2种核桃蚜虫潜在适生区分析

【目的】分析核桃黑斑蚜与核桃全斑蚜在全球范围内的潜在分布,比较气候变化对其分布的影响,为核桃有害生物综合管理策略的制定提供依据。【方法】基于实验室和野外试验,结合CLIMEX软件对核桃黑斑蚜与核桃全斑蚜在目前及未来气候条件下的潜在地理分布进行了模拟和系统评估。【结果】2种核桃蚜虫适生区十分相似,在世界范围内主要分布区集中在欧洲、北美洲、亚洲等区域,核桃黑斑蚜适生区范围大于核桃全斑蚜,但在我国,核桃黑斑蚜适生区范围小于核桃全斑蚜。气候变化将决定2种蚜虫分布的差异性,未来气候情景下,2种蚜虫适生区将发生变化,在欧洲、北美洲和亚洲适生区范围向高纬度延伸;在我国适生区范围逐渐减小。【结论】在世界范围内,核桃黑斑蚜与核桃全斑蚜适生区域主要分布在25°N-75°N内的亚洲、欧洲、北美洲的部分地区;在我国,其适生区域主要分布在东部季风区内的东北的南部、西北东南部、西南中部、华中北部以及华北地区。     

Host stage preference and parasitism behaviour of Aenasius bambawalei an encyrtid parasitoid of Phenacoccus solenopsis

In Pakistan, the cotton mealybug, Phenacoccus solenopsis Tinsley (Sternorrhyncha (Homoptera): Pseudococcidae), is a serious pest of many cultivated plants. A parasitoid, Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae), is associated with P. solenopsis. In order to mass rear A. bambawalei for a biological control programme, it is important to investigate the parasitoid’s host stage preference and its parasitism behaviour for P. solenopsis in order to optimise production. The present study showed that under both choice and no-choice conditions, the parasitoid preferred third instar and pre-reproductive host stage mealybugs for parasitism. Parasitoid larva developing inside the host exhibited a greater longevity, shorter developmental period and longer body size in these preferred host stages. Our study also confirmed that A. bambawalei showed no attraction to male mealybugs and no host feeding on any host stage was recorded. The ability of the parasitoid to effectively discriminate between suitable and non-suitable stages means that it is feasible to rear it on a mixed population.     

Effects Of Tending By Solenopsis Invicta (Hymenoptera: Formicidae) On The Sugar Composition And Concentration In The Honeydew Of An Invasive Mealybug,Phenacoccus Solenopsis (Hemiptera: Pseudococcidae)

Mutualistic interactions between ants and hemipterans are mediated by the honeydew produced by the hemipterans. Previous works have demonstrated that the invasive mealybug Phenacoccus solenopsis produces abundant honeydew and attracts a large number of workers of the fire ant Solenopsis invicta. Mealybugs exhibit higher fecundity when tended by fire ants. The honeydew produced by P. solenopsis plays an important role in interactions between these two species. However, relatively few studies have focused on whether there is a cost to P. solenopsis mealybugs of being tended by S. invicta through changes in their excretion behavior and the quantity of honeydew produced. Our results indicated that the honeydew of P. solenopsis contains xylose, fructose, sucrose, trehalose, melezitose, and raffinose. The sugar concentration in the mealybug honeydew changed in an ant‐tended treatment. When tended by fire ants, the mealybugs generated honeydew with a significantly decreased xylose concentration. In contrast, the droplets showed a considerable increase in the melezitose concentration. P. solenopsis excreted honeydew more frequently when tended by S. invicta, but the weights of the droplets excreted by the ant‐tended mealybugs were significantly lower. In addition, S. invicta exhibited a significant preference for different sugars. Melezitose was visited more intensively than the other sugars in two choice tests. These results may suggest that, to attract more tending ants, mealybugs adjust their carbohydrate metabolism.     

Predicting the spread of Aedes albopictus in Australia under current and future climates: Multiple approaches and datasets to incorporate potential evolutionary divergence

When predicting the potential and future invasive range of a species, there is a growing appreciation that insights about factors limiting distributions can be provided by using multiple modelling approaches and by incorporating information from different parts of a species range. Here we apply this strategy to build on previous CLIMEX models to predict the invasion potential of Aedes albopictus, the Asian tiger mosquito, in mainland Australia. A combination of CLIMEX and MAXENT modelling indicated that the mosquito was expected to become widespread along the eastern seaboard and extend into northern Tasmania, but to remain restricted to the coastal fringe, a pattern which is not expected to shift much under climate change. However, a recent expansion of A. albopictus in North America points to evolutionary changes affecting the distribution of this species; when the North American range is included in models, A. albopictus is predicted to become much more widespread and extend inland and into Western Australia. These patterns highlight the potential impact of evolution on species distributions arising from multiple introductions or in situ evolution. By considering future climate scenarios, we demonstrate that there is likely to be a persistent public health threat associated with invasion by this species.     

Potential distribution of Schistocerca gregaria gregaria in southwestern Asia

1. The northern subspecies of desert locust Schistocerca gregaria gregaria has recently expanded into western Asia. It poses a serious threat to food security in areas that are already socially and politically unstable. Its further expansion into other parts of southwestern Asia is an issue of great concern (e.g., China).
2. We assembled S. g. gregaria occurrence records that were accumulated by the Food and Agriculture Organization and environmental variables that summarized aspects of climate, soil condition and vegetation. We predicted the potential distribution of S. g. gregaria via the fine-tuned Maxent model and ensemble ecological niche model approaches.
3. The models predicted that India and other southwestern Asian countries face high risk of S. g. gregaria invasion because of the presence of suitable habitats and the absence of natural barriers that would prevent S. g. gregaria dispersal into these areas. By contrast, the risk of S. g. gregaria invasion in China is low because the suitability values were very low. Moreover, the Tianshan Mountains, the Kunlun Mountains and the Himalaya Mountains may act as natural barriers against S. g. gregaria dispersal.
4. Responses of S. g. gregaria to these environmental variables were modelled using fine-tuned Maxent models.

     

Effects of Transgenic Cry1Ac + CpTI Cotton on Non-Target Mealybug Pest Ferrisia virgata and Its Predator Cryptolaemus montrouzieri

Recently, several invasive mealybugs (Hemiptera: Pseudococcidae) have rapidly spread to Asia and have become a serious threat to the production of cotton including transgenic cotton. Thus far, studies have mainly focused on the effects of mealybugs on non-transgenic cotton, without fully considering their effects on transgenic cotton and trophic interactions. Therefore, investigating the potential effects of mealybugs on transgenic cotton and their key natural enemies is vitally important. A first study on the effects of transgenic cotton on a non-target mealybug, Ferrisia virgata (Cockerell) (Hemiptera: Pseudococcidae) was performed by comparing its development, survival and body weight on transgenic cotton leaves expressing Cry1Ac (Bt toxin) + CpTI (Cowpea Trypsin Inhibitor) with those on its near-isogenic non-transgenic line. Furthermore, the development, survival, body weight, fecundity, adult longevity and feeding preference of the mealybug predator Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) was assessed when fed F. virgata maintained on transgenic cotton. In order to investigate potential transfer of Cry1Ac and CpTI proteins via the food chain, protein levels in cotton leaves, mealybugs and ladybirds were quantified. Experimental results showed that F. virgata could infest this bivalent transgenic cotton. No significant differences were observed in the physiological parameters of the predator C. montrouzieri offered F. virgata reared on transgenic cotton or its near-isogenic line. Cry1Ac and CpTI proteins were detected in transgenic cotton leaves, but no detectable levels of both proteins were present in the mealybug or its predator when reared on transgenic cotton leaves. Our bioassays indicated that transgenic cotton poses a negligible risk to the predatory coccinellid C. montrouzieri via its prey, the mealybug F. virgata.     

Crop dominance exerts specific effects on foliage‐dwelling arthropods in Bacillus thuringiensis cotton

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