Phloem‐specific resistance in Brassica oleracea against the whitefly Aleyrodes proletella

The cabbage whitefly [Aleyrodes proletella L. (Hemiptera: Aleyrodidae)] is becoming a serious pest in Brassica oleracea L. (Brassicaceae) crops. However, almost nothing is known about the interaction of this insect with its host plants. Previous studies have shown differences in the natural occurrence of adults, eggs, and nymphs on the closely related B. oleracea cultivars Christmas Drumhead and Riviera grown in the field. In this study, we aimed to identify the nature of these differences and to gain insight into the resistance mechanisms against A. proletella. We used no‐choice experiments on field‐ and greenhouse‐grown plants to show that the differences between the two cultivars are mainly based on antibiosis (traits that reduce herbivore performance) and not on antixenosis (traits that deter herbivory). This was further supported by laboratory choice experiments that indicated little or no discrimination between the two cultivars based on plant volatiles. We showed that resistance is dependent on plant age, that is, resistance increased during plant development, and is mainly independent of environmental factors. Analysis of probing behaviour revealed that the resistance trait affects A. proletella at the phloem level and that morphological differences between the two cultivars are most likely not involved. We suggest that compounds present in the phloem reduce sap ingestion by the whitefly and that this explains the observed resistance.     

Do western boxelder bugs sunbathe for sanitation? Inferences from in vitro experiments

When western boxelder bugs, Boisea rubrolineata (Barber) (Hemiptera: Rhopalidae), form aggregations in warm sunlight, they release from their posterior dorsal abdominal gland an odorous blend of monoterpenes with heretofore unknown biological function. In laboratory analyses and experiments, we show that bugs in warm sunlight, but not in shade, exude and spread copious amounts of monoterpenes onto their cuticle. These monoterpenes do not serve as a pheromone, but rather as a means of sanitation. They inhibit germination of conidia of the fungal pathogen Beauveria bassiana (Bals.‐Criv.) Vuill. (Hypocreales) as well as halt the growth of germinated spores. This prophylactic defense against pathogens appears adaptive for phytophagous insects, like B. rubrolineata, that are prone to infections by microbes thriving on leaf surfaces and in the insects' overwintering microhabitat.     

Resistance to Melanaphis sacchari in the sugarcane cultivar R 365

This study focuses on the resistance of sugarcane, Saccharum spec. (Poaceae), to the sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), which vectors Sugarcane yellow leaf virus (SCYLV). Resistance was characterized in cultivar R 365, using a 3‐year field trial and laboratory experiments on potted plantlets and excised leaves. R 365 reduced aphid populations in the field by antixenosis and antibiosis. Using the electrical penetration graph technique, we detected delayed aphid salivation in phloem and inhibition of passive phloem sap uptake in R 365. The resistance factors also proved to be effective against the corn leaf aphid, Rhopalosiphum maidis (Fitch) (Hemiptera: Aphididae), another vector of SCYLV.     

Settling behavior of the glassy‐winged sharpshooter,Homalodisca vitripennis,vector of Xylella fastidiosa,on southern highbush blueberry cultivars

The xylem‐limited bacterium Xylella fastidiosa Wells, Raju, Hung, Wiseberg, Mandelico‐Paul & Brenner causes bacterial leaf scorch, a new disease of southern highbush blueberry [Vaccinium corymbosum L. (Ericaceae) interspecific hybrids] in the southeastern USA. The bacterium is transmitted by sharpshooter leafhoppers (Hemiptera: Cicadellidae), with the glassy‐winged sharpshooter (GWSS), Homalodisca vitripennis (Germar), being the most common potential vector in blueberry plantings. Considerable differences are observed in disease intensity among blueberry cultivars in the field, but it remains unknown whether these differences are due to variations in cultivar susceptibility to the bacterium, differences in attractiveness to its vector(s), or both. The settling and feeding behavior of GWSS was evaluated on three southern highbush blueberry cultivars (FL 86‐19, Star, and Emerald) in the greenhouse; in previous field studies, these cultivars were found to be affected by bacterial leaf scorch at high, moderate, and low levels, respectively. Potted plants were caged together with field‐collected GWSS adults for a period of 5 days, with either all three cultivars caged simultaneously (choice test) or individually (no‐choice test). In the choice tests, no differences in cultivar attractiveness were observed during the first 2 days of study. However, from the 3rd day, significantly more adults settled on Emerald (52.7%) than on Star (25.5%) and FL 86‐19 (17.7%). In contrast, in no‐choice tests, the overall host plant acceptance for the three cultivars was similar, and 89.3–92.1% of adults settled on these plants. A significantly greater number of adults settled on the stems (79.3%) vs. the leaves (11.2%). Moreover, they preferred the middle portion of the shoot (56.9%) compared with the upper (7.8%) and the lower (14.7%) portions. In a separate study on FL 86‐19, greater numbers of GWSS nymphs settled on the upper (actively growing) portion of the shoot (82.3%), whereas only 15.8 and 1.5% settled on the middle and lower portions, respectively.     

Genetic divergence is decoupled from ecological diversification in the hawaiian nesosydne planthoppers

Adaptive radiation involves ecological shifts coupled with isolation of gene pools. However, we know little about what drives the initial stages of divergence. We study a system in which ecological diversification is found within a chronologically well-defined geological matrix to provide insight into this enigmatic phase of radiation. We tested the hypothesis that a period of geographic isolation precedes ecological specialization in an adaptive radiation of host-specialized Hawaiian planthoppers. We examined population structure and history using mitochondrial and multiple independent microsatellite loci in a species whose geographic distribution on the island of Hawaii enabled us to observe the chronology of divergence in its very earliest stages. We found that genetic divergence is associated with geographic features but not different plant hosts and that divergence times are very recent and on the same timescales as the dynamic geology of the island. Our results suggest an important role for geography in the dynamics of the early stages of divergence.     

Population genetic structure of a specialist leafhopper on Zea: likely anthropogenic and ecological determinants of gene flow

Corn leafhopper, Dalbulus maidis DeLong & Wolcott (Hemiptera: Cicadellidae), is a specialist herbivore on the genus Zea (Poaceae). The genera Dalbulus and Zea evolved in central Mexico. We sought to determine whether population genetic structuring is prevalent in corn leafhoppers inhabiting three of its host plants: (1) the highland species perennial teosinte (Zea diploperennis Iltis, Doebley & Guzman), (2) the mid‐ to lowland‐species Balsas teosinte (Zea mays ssp. parviglumis Iltis & Doebley), and (3) the ubiquitous domesticated maize (Zea mays ssp. mays L.). We used amplified fragment length polymorphisms to detect population structuring and genetic differentiation among corn leafhoppers on the three host plants in western‐central and ‐northern Mexico. Our results showed that corn leafhopper in Mexico is composed of at least two genetically discrete populations: an ‘Itinerant’ population associated with the annual hosts maize and Balsas teosinte, which appears to be widely distributed in Mexico, and a ‘Las Joyas’ population restricted to perennial teosinte and confined to a small mountain range (Sierra de Manantlán) in western‐central Mexico. Our results further suggested that population structuring is not due to isolation by distance or landscape features: Las Joyas and Itinerant corn leafhopper populations are genetically distinct despite their geographic proximity (ca. 4 km), whereas Itinerant corn leafhoppers separated by hundreds of kilometers (>800 km), mountain ranges, and a maritime corridor (Sea of Cortez) are not genetically distinct. Based on our results and on published ethnohistorical and archaeological data, we propose pre‐Columbian and modern scenarios, including likely ecological and anthropogenic influences, in which the observed genetic population structuring of corn leafhopper could have originated and could be maintained. Also, we hypothesize that after evolving on the lowland Balsas teosinte, corn leafhopper expanded its host range to include maize and then the highland perennial teosinte, following the domestication and spread of maize within the last 9 000 years.     

中国象蜡蝉科一新属新种（半翅目：蜡蝉总科）

记述中国象蜡蝉科(半翅目:蜡蝉总科)1新属:滕象蜡蝉属 Dictyotenguna gen. n.,其模式种为周氏滕象蜡蝉 Dictyotenguna choui sp. nov..简要介绍了东洋界和东古北界象蜡蝉系统学发展概况。模式标本保存于中国科学院动物研究所国家动物博物馆。     

中国蝽科新记录属种（半翅目：异翅亚目）

报道中国蝽科(Heteroptera: Pentatomidae)3个中国新记录属:库蝽属 Cuspicona Dallas、赫蝽属Hermolaus Distant、昂角蝽属 Oncinoproctus Breddin,以及6个新记录种:绿库蝽 Cuspicona antica Vollenhoven、赫蝽 Hermolaus typicus Distant、笑曼蝽 Menida atkinsoni Distant、昂角蝽 Oncinoproctus griseolus Breddin、斑卷蝽 Paterculus aberrans Distant 和短线鳖蝽 Rolstoniellus malacanicus (Yang)。并给出各种的虫体背腹面照片和生殖节结构图。除绿库蝽的观察标本保存在中国科学院动物所(IZCAS)以外,其余研究观察标本保存在南开大学昆虫研究所标本馆(NKUM)。     

中国圆顶瓢蜡蝉属回顾及一新种描记（半翅目：蜡蝉总科：瓢蜡蝉科）

对中国圆顶瓢蜡蝉属Thabena Stl,1861进行了分类回顾,共有4种:海南圆顶瓢蜡蝉T.hainanensis(Ran & Liang,2006)(中国海南)、兰坪圆顶瓢蜡蝉T.lanpingensis sp.nov.(中国云南)、黎桃圆顶瓢蜡蝉T.litaoensis(Yang,1994)(中国台湾、海南)和云南圆顶瓢蜡蝉T.yunnanensis(Ran & Liang,2006)(中国云南)。对其中2个种兰坪圆顶瓢蜡蝉T.lanpingensis和黎桃圆顶瓢蜡蝉T.litaoensis进行了描记或重新描记,绘制了特征图。提供了中国圆顶瓢蜡蝉属全部已知种的检索表。     

红足点胸长蝽Acompus rufipes (Wolff) 新异名（异翅亚目：长蝽总科：地长蝽科）

研究欧洲和中国的标本后发现,室翅长蝽科Heterogastridae的小异腹长蝽Heterogaster minimusZou&Zheng,1981是地长蝽科Rhyparochromidae的红足点胸长蝽Acompus rufipes(Wolff,1804)的新异名。文中还提供了红足点胸长蝽Acompus rufipes的整体图和雄性生殖器特征图。