A life table ofMogannia iwasakii (Homoptera: Cicadiidae) in sugarcane field of Okinawa

A preliminary life table of the sugarcane cicada, Mogannia iwasakii, which became a pest of sugarcane in Okinawa recently, was presented based on the results of field survey. Mortality rates during egg and later nymphal stages were low but a remarkable reduction of the number of individuals in a cohort took place at the 1st nymphal instar, mainly due to predation by ants. Ants also killed the cicada during and just after the final ecdysis and birds concentrated their feeding on adults. Prenatal mortality of adults was, however, low in the infested area, suggesting the ‘escape’ of cicadas from the pressure of predators. This espace is considered to be a factor responsible to the maintainance of outbreak for a long time. Increase in the acreage of ratton canes and wide-use of organochlorine insecticides during the 1960's were assumed to be the factors responsible to the initial increase of this species.     

‘Predator-foolhardiness’ in an epidemic cicada population

‘Predator-foolhardiness’ (Lloyd andDybas , 1966b) in an epidemic population of the sugarcane cicada, Mogannia minuta was tested by counting the number of successful and failed trials of hand-capturing of adults in the centre and periphery of a heavily infested area. Males frequently failed to escape from capture in the outbreak area but they did not in the peripheral zone. Females could escape well irrespective of the density. It was considered that the ‘predator-foolhardiness’ of males is not due to genetic differentiation through the process of outbreak but to the effect of massive chorus on the escape behaviour.     

Inoculum Sources for the Spread of Leaf Scald Disease of Sugarcane Caused by Xanthomonas albilineans in Guadeloupe

Leaf scald of sugarcane, caused by Xanthomonas albilineans, is thought to be spread mainly in infected cuttings and transmitted on infested cutting implements. Several observations made in Guadeloupe indicated that other means of spreading also occur. The dispersal of the pathogen outside sugarcane was investigated with plants inoculated by an antibiotic-resistant marked strain of X. albilineans and with plants naturally infested with wild strains of the pathogen. The bacteria were isolated in water droplets (rain or dew) on the surface of sugarcane leaves at dawn. It was also detected on the surface of dry leaves during the day by leaf imprinting onto a selective culture medium. The bacteria were much more frequently isolated from the surface of symptomatic leaves than from symptomless ones. Aerial dispersal of X. albilineans was investigated by placing Petri dishes containing selective culture medium between sugarcane plants but without direct contact with the leaves. The pathogen was isolated in four out of 270 dishes which were randomly set 3–14 h in a diseased field. These results indicated that the pathogen exuded from the leaves and then was spread by aerial means (rain, insects, …) or by leaf contact. The bacteria were also found in roots and rhizospheric soil of infested sugarcane stools suggesting that X. albilineans could be transmitted by root to root contact or by the soil. Finally, isolations of the pathogen in sugarcane inflorescences were positive. So, fuzz transmission may also occur.     

Inoculum Sources for the Spread of Leaf Scald Disease of Sugarcane Caused by Xanthomonas albilineans in Guadeloupe

Leaf scald of sugarcane, caused by Xanthomonas albilineans, is thought to be spread mainly in infected cuttings and transmitted on infested cutting implements. Several observations made in Guadeloupe indicated that other means of spreading also occur. The dispersal of the pathogen outside sugarcane was investigated with plants inoculated by an antibiotic-resistant marked strain of X. albilineans and with plants naturally infested with wild strains of the pathogen. The bacteria were isolated in water droplets (rain or dew) on the surface of sugarcane leaves at dawn. It was also detected on the surface of dry leaves during the day by leaf imprinting onto a selective culture medium. The bacteria were much more frequently isolated from the surface of symptomatic leaves than from symptomless ones. Aerial dispersal of X. albilineans was investigated by placing Petri dishes containing selective culture medium between sugarcane plants but without direct contact with the leaves. The pathogen was isolated in four out of 270 dishes which were randomly set 3-14 h in a diseased field. These results indicated that the pathogen exuded from the leaves and then was spread by aerial means (rain, insects,…) or by leaf contact. The bacteria were also found in roots and rhizospheric soil of infested sugarcane stools suggesting that X. albilineans could be transmitted by root to root contact or by the soil. Finally, isolations of the pathogen in sugarcane inflorescences were positive. So, fuzz transmission may also occur.     

Why a cicada, Mogannia minuta Matsumura, became a pest of sugarcane: an hypothesis based on the theory of 'escape'

Abstract. 1. Life tables were constructed for natural populations of a cicada. Mogannia minuta , during an outbreak in sugarcane fields at Okinawa to determine possible reasons for the outbreak.
2. The highest mortality during the life cycle was during the beginning of the nymphal stage, and was mainly due to predation by ants.
3. The estimated rate of natural increase based on a survivorship—fecundity schedule in sugarcane fields was near unity, but during the increasing period the rate was estimated to be substantially higher than unity.
4. The rate of natural increase in Miscanthus -grassland was slightly negative, suggesting that the grassland population was maintained by immigration of adults from sugarcane fields.
5. Escape from predation may be the main cause of the special distribution pattern and the maintenance of extraordinarily high densities for many years.     

Spatial correlations of Diceroprocta apache and its host plants: evidence for a negative impact from Tamarix invasion

Abstract 1. The hypothesis that the habitat‐scale spatial distribution of the Apache cicada Diceroprocta apache Davis is unaffected by the presence of the invasive exotic saltcedar Tamarix ramosissima was tested using data from 205 1‐m² quadrats placed within the flood‐plain of the Bill Williams River, Arizona, U.S.A. Spatial dependencies within and between cicada density and habitat variables were estimated using Moran's I and its bivariate analogue to discern patterns and associations at spatial scales from 1 to 30 m. 2. Apache cicadas were spatially aggregated in high‐density clusters averaging 3 m in diameter. A positive association between cicada density, estimated by exuvial density, and the per cent canopy cover of a native tree, Goodding's willow Salix gooddingii, was detected in a non‐spatial correlation analysis. No non‐spatial association between cicada density and saltcedar canopy cover was detected. 3. Tests for spatial cross‐correlation using the bivariate I_YZ indicated the presence of a broad‐scale negative association between cicada density and saltcedar canopy cover. This result suggests that large continuous stands of saltcedar are associated with reduced cicada density. In contrast, positive associations detected at spatial scales larger than individual quadrats suggested a spill‐over of high cicada density from areas featuring Goodding's willow canopy into surrounding saltcedar monoculture. 4. Taken together and considered in light of the Apache cicada's polyphagous habits, the observed spatial patterns suggest that broad‐scale factors such as canopy heterogeneity affect cicada habitat use more than host plant selection. This has implications for management of lower Colorado River riparian woodlands to promote cicada presence and density through maintenance or creation of stands of native trees as well as manipulation of the characteristically dense and homogeneous saltcedar canopies.     

Leptodictya tabida (Hemiptera: Tingidae): a potential threat to sugarcane production in Lower Rio Grande Valley of Texas

Areawide surveys and replicated cultivar trials were conducted in 2001 and 2002 in sugarcane (Saccharum spp.) fields in the Lower Rio Grande Valley of Texas to assess the distribution and incidence of the sugarcane tingid Leptodictya tabida (Herrich-Schaeffer). L. tabida was found in all fields surveyed during both years, infesting 60 and 68% of the plants, respectively. The average percentage of leaves infested was 11% in 2001 and 15% in 2002. In 2001, 'CP70-1133' was the most infested, 'CP72-1210' was the least infested, and intermediate infestation levels were evident in 'CP70-321' and 'TCP87-3388'. In 2002, however, TCP87-3388 and CP70-321 were more heavily infested, and CP71-1240 and CP71-1405 were the least infested. Mean densities of L. tabida recovered per plant varied between 1.2 bugs on CP72-1210 and 5.1 on CP70-1133 in 2001, and in 2002, from zero bugs on CP71-1240 and CP71-1405 to 5.3 on CP72-1210. In the cultivar trials, cultivar differences also were evident in both plant and leaf infestation levels, and the proportion of immatures to total L. tabida populations; 'HoCP91-555' had the lowest L. tabida infestations and 'NCo-310' had the greatest levels in both years. Although >5000 L. tabida from the field were collected and kept in the laboratory, no parasitoids were found. The distribution of the infestations during the surveys and in the field trial evaluations suggested that L. tabida populations have been spreading in sugarcane across the Lower Rio Grande Valley. Potential varietal resistance mechanisms are discussed.     

Physical and chemical variability in sugarcane fields infested with the red-striped soft scale insect,Pulvinaria Tenuivalvata (Newstead)

The red-striped soft scale insect Pulvinaria tenuivalvata (Newstead) (Hemiptera: Coccidae) started to infest sugarcane plants (Saccharum officinarum L.) in different districts in Egypt during the last decade. The percentage of infestation was recorded in El-Wakf area, Qena Governorate (Naghhamadi mill zone) Upper Egypt in some fields. There are three levels of infestation, low, intermediate and high. From these fields, samples were selected for physical and chemical studies. The results obtained show that the stalks of infested plants decreased in weight, the sugar content (glucose and sucrose) drastically reduced and as the percentage of infestation increased the percentage of glucose and sucrose content significantly decreased. The primary and secondary humidity and the cellulose content also increased in the healthy plants compared to the infested ones. All the physical character of the infested plants was significantly affected in comparison with the healthy ones.     

Predicting economic losses from the continued spread of the Mexican rice borer (Lepidoptera: Crambidae)

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive species that originated from Mexico, and it is threatening to cause major economic losses to sugarcane, Saccharum spp., and rice, Oryza sativa L., industries in Louisiana. The insect is expected to reach sugarcane and rice production areas in Louisiana by 2008, and infest all of Louisiana sugarcane and rice industries by 2035. When all sugarcane in Louisiana becomes infested, annual yield losses of $220 million would be expected for a cultivar of comparable susceptibility to LCP 85-384 (assuming this cultivar is planted on 100% of the production area). This also assumes the use of the current practice of rainfed production and one application of insecticide, which is presently used by farmers in Louisiana. Irrigation with 30 cm of water is predicted to reduce estimated losses by 29%, whereas four applications of a biorational insecticide such as tebufenozide are expected to reduce the loss in revenue by 53%. The use of the resistant 'HoCP 85-845' would reduce the projected loss in revenue by 24%. Combining all three management tactics on sugarcane, anticipated net loss in revenue would decrease by 66%. The rice industry in Louisiana is projected to suffer from a loss in revenue of $45 million when the entire state is infested. A 77% reduction in loss in revenue is expected with one application of lambda-cyhalothrin. A quarantine on east Texas sugarcane is estimated to save the Louisiana industry between $1.1 billion and $3.2 billion (depending on management) during the time needed for the insect to fully invade the state's sugarcane and rice producing area by natural migration rather than by accidental introduction. The rapid deployment of appropriate management tactics will have a key role in reducing the anticipated economic impact of E. loftini once it becomes a pest in Louisiana sugarcane and rice.     

Impact of an introduced ant on native rain forest invertebrates: Pheidole megacephala in monsoonal Australia

Pheidole megacephala is an exotic ant species that has severely affected native invertebrate biodiversity throughout the tropics. Its impacts have been documented extensively in relatively depauperate invertebrate communities, but not in species-rich habitats such as tropical rain forests. Here we describe the local distribution of P. megacephala and its impacts on native invertebrate assemblages in and around a rain forest patch at Howard Springs, in Australia's monsoonal tropics. P. megacephala was found to be confined to a single area of approximately 25 ha, with its distribution centered on drainage lines and the rain forest. Significant but weak correlations were found between its abundance and vegetative canopy cover (positive) and distance from the rain forest (negative). In the most heavily infested area within the rain forest, the abundance of P. megacephala was 37–110 times that of total native ant abundance found within uninfested plots, as measured by pitfall traps. The abundance and richness of native ants and other invertebrates were significantly reduced in litter samples, pitfall catches and foliage beats where P. megacephala was present, inversely relative to the abundance of P. megacephala. Only two individuals of a single native ant species were found within the most infested plot, with native ant richness being reduced to about half in the least infested plot. The most persistent functional groups of native ants in infested plots were Cryptic species, which forage primarily within soil and leaf litter, and Opportunists, which exhibit highly generalised foraging behaviour. The highest abundance of P. megacephala corresponded with a 42–85% decrease in the abundance of other native invertebrates. Insect larvae were totally absent from foliage beats collected at the most heavily infested plot. P. megacephala was found overall to be expanding its range, averaging 12 m range expansion in the dry season and contracting 7 m in the wet season. It is able to spread into surrounding savanna habitats by occupying relatively sheltered microsites, such as beneath logs and at the bases of trees. However, it is unlikely to attain high population densities in open savanna habitats because of its relative intolerance of desiccation, and the prevalence of behaviourally dominant native ant species. Howard Springs is currently the only rain forest patch in monsoonal Australia known to be infested by P. megacephala, but clearly this ant is a serious potential threat to the region's rain forest invertebrate fauna. Received: 19 August 1998 / Accepted: 12 May 1999     

蒙古寒蝉成、若虫触角形态及若虫龄期判别研究（半翅目：蝉科）

对蒙古寒蝉若虫与成虫的触角感器进行了研究,并结合不同龄期若虫触角的形态特征,采用Dyar法则与“头宽—龄期”的回归曲线验证,初步断定蒙古寒蝉若虫具有4个龄期。不同龄期若虫与成虫的触角形态差异显著,触角感器的种类、数量和分布也明显不同,其差异或与若虫和成虫的生态位不同密切相关。     

Life history and geographical distribution of the walnut twig beetle,Pityophthorus juglandis (Coleoptera: Scolytinae), in southern Europe

In September 2013, the walnut twig beetle (WTB) Pityophthorus juglandis Blackman, a species native to Mexico and south‐western USA, was recorded for the first time in Europe, in northern Italy. The collected adults were found to be vector of the fungus Geosmithia morbida Kola?ik, Freeland, Utley & Tisserat, an aggressive pathogen causing thousand cankers disease in walnut (Juglans spp.). To determine the geographical distribution of the WTB and the main aspects of biology, phenology and voltinism, an intensive survey of the main walnut plantations near the site of the first finding was conducted in 2014. The beetles began to fly with a mean air temperature of about 18°C (mid‐May) and continued until late October. Two partially overlapping generations occurred, with the second taking place in late September. The WTB was found in 14 of the 27 monitored walnut plantations. The infested sites were spread over four different non‐contiguous administrative provinces belonging to two regions (Veneto and Lombardy) of northern Italy. The most distant infested plantations were about 130 km apart along a west–east gradient, and about 70 km along a north–south gradient. In this respect, the distribution area of the WTB in northern Italy may be prudently estimated at about 4200 km². Molecular analysis of the collected individuals showed no genetic differences among the six sampled P. juglandis populations, suggesting that a few individuals might have arrived in Italy through a single introduction event and then spread over the territory. Given the quick mortality of infested walnuts and the wide distribution area, eradication strategies appear unrealistic. Possible strategies of biological control or local chemical treatments must be investigated.     

The effect of the cassava green mite Mononychellus tanajoa on the growth and yield of cassava Manihot esculenta in a seasonally dry area in Kenya

The effect of the cassava green mite Mononychellus tanajoa on the growth and yield of cassava Manihot esculenta was studied over a 10-month period in two field trials near Lake Victoria in Kenya. One plot was maintained free of mites by means of acaricide, while the other was artificially infested.The highest population density of M. tanajoa occurred during the dry season. A maximum leaf area index (LAI) of about 2 was reached at the onset of the dry season. The total leaf area of mite infested plants was reduced compared with uninfested plants during the dry spell. During the following rainy season infested plants recovered and attained the same leaf area as uninfested plants. A multiple regression model predicting the leaf area showed that 58% of the seasonal variation could be explained by plant age, soil water, and leaf injury.The net growth rate of infested plants was lower than that of uninfested plants. Maximum values of 21 (infested plants) and 49 (uninfested plants) g m^-2 week^-1 were attained at the onset of the second rainy season. No difference was found between uninfested and infested plants with respect to net assimilation rates per unit leaf area during the dry season. The net assimilation rates reached a maximum almost at the same time as the growth rates, but the infested plants peaked slightly earlier and at a lower level than the uninfested plants. M. tanajoa did not affect the relative allocation of dry matter into stems and storage roots, but the absolute allocation of dry matter declined with increasing mite injury. Thus, after 10 months the dry matter of infested plants was reduced by 29% and 21% for storage roots and stems, respectively, compared with the uninfested plants.     

Occurrence and impact ofPhytomyza orobanchia [Diptera: Agromyzidae] onOrobanche crenata [Orobanchaceae] in Syria

A survey was carried out in 1988 to determine the occurrence and distribution of the flyPhytomyza orobanchia Kaltenbach [Diptera: Agromyzidae] on broomrape (Orobanche crenata Forskal) at 21 locations in northwestern Syria. Fruit capsules of broomrape were examined in faba bean (Vicia faba L.) fields. The fly was present at 95% of the locations sampled. Of 630 broomrape plants examined over all locations, 55.5% were infested. Of the 1,890 capsules examined, 32.5% were attacked. Fly populations were highest near the coast where 79% of the broomrapes were damaged. The total seed output of broomrape plants was reduced by 29.4% in the surveyed area due to a mean seed destruction of 91.1% per infested broomrape capsule.      

Numbers of pink sugarcane mealy bug, Saccharicoccus sacchari (Cockerell) (Hemiptera: Pseudococcidae), differ within seasons and among regions and stages of the sugarcane crop cycle

Abstract  The pink sugarcane mealy bug (PSMB; Saccharicoccus sacchari ) is widespread on sugarcane globally. PSMB infest above-ground storage tissue as it develops, feeding on phloem and producing exudate. It is not known, however, whether the level of infestations is the same in different sugar growing regions, or how population size varies year to year within a region. Field surveys of the number of nodes infested were conducted over five seasons in three mill-regions in northern Australia (Macknade, Kalamia and Marian) on plant and ratoon crops. The pattern of infestation was very similar across seasons (only in 1 year of very low rainfall was the increase in population delayed). In all three regions the proportion of nodes infested was similar but reached the maximum 1 month later in the Marian region compared with the Kalamia and Macknade regions. The Kalamia region was distinguished by the rapid decline in the number of nodes infested down to a very low level by March. In the Macknade region mealy bugs persisted at higher levels than the other two regions. The PSMB infestation started earlier and was much greater in ratoon crops than plant crops throughout the sampling period. The differences were more pronounced in the Macknade and Marian districts. These observations provide a firm basis from which future strategies to control PSMB can be developed.     

Sampling for the sugarcane borer (Lepidoptera: Crambidae) on sugarcane in Louisiana.

A 3-yr study was conducted in 0.6- to 2.0-ha sugarcane fields throughout south Louisiana under varying sugarcane borer, Diatraea saccharalis (F.), density levels to determine the spatial dispersion of infestations and to develop a sequential sampling plan. Infestations of D. saccharalis were randomly dispersed. Infestation levels (percentage of stalks infested) ranged from 0.6 to 33.3%. Frequency distributions of the number of infested stalks indicated that the Poisson distribution best fit the data Tests of other distributions (negative binomial [aggregated], binomial [uniform], geometric, and hypergeometric) resulted in poorer fits. The sequential sampling plan devised, with lower and upper D. saccharalis infestation limits of 2 and 5% and 5 and 10%, required maximum average sample numbers of 7.1 and 5.5 (20-stalk samples), respectively, to make terminating management decisions. It is our assessment that implementation of these plans would decrease sampling effort by 50-60% when compared with sampling programs currently in use for D. saccharalis management decisions in Louisiana.     

Songs,genetics, and morphology: revealing the taxonomic units in the European Cicadetta cerdaniensis cicada group,with a description of new taxa (Hemiptera: Cicadidae)

Recent acoustic studies have revealed that Cicadetta montana (Scopoli, 1772), which was once thought to be a single widespread Palaearctic cicada species, is actually a complex of many taxa. Although some song patterns are very distinct, others comprise groups of closely related species, as in the case of Cicadetta cerdaniensis Puissant & Boulard, 2000, Cicadetta cantilatrix Sueur & Puissant, 2007, and Cicadetta anapaistica Hertach, 2011. Seven spatially or behaviourally isolated metapopulations belonging to this song group from Italy and Switzerland were detected and investigated using acoustic, molecular, and morphological methods. Taxonomic decisions in this group are challenging because of a lack of truly diagnostic morphological characters, variously coloured morphs, qualitatively intermediate song patterns in contact zones, and strong temperature dependence of song‐duration characters. Molecular genetic studies suggest rapid speciation resulting in incomplete lineage sorting and introgression. It is only by using multiple sources of data that species can be delimited. The new species C icadetta sibillae sp. nov. and the new subspecies C icadetta anapaistica lucana ssp. nov. were described using the microstructure of the male calling songs. C icadetta sibillae sp. nov. occurs from southern Switzerland to central Italy, and is the most abundant cicada in the Northern Apennine. C icadetta anapaistica lucana ssp. nov. is endemic to a small southern Italian distribution range, and seems to be threatened by habitat loss and fragmentation. There is strong evidence that current distribution patterns and phylogenetic relationships of the Cicadetta cerdaniensis group are linked to speciation events in Pleistocene glacial refugia in the Italian, Iberian, and Balkan peninsulas. © 2015 The Linnean Society of London     

褐梗天牛幼虫和成虫空间分布的地统计学研究

褐梗天牛(Arhopalus rusticus Linnaeus)是一种对松、杉、柏等林木危害非常严重的蛀干害虫,主要危害针叶树的衰弱木以及火灾后的枯立木,是继松褐天牛之后携带拟松材线虫能力最强的蛀干害虫。为了更好地控制其危害,深入地研究其种群空间格局,运用地统计学方法分析了3块受害程度不同的油松林内褐梗天牛幼虫和成虫的空间分布特性。结果表明:3种受害程度不同的林分内,褐梗天牛的危害具有显著差异,轻度受害林分内有虫株率为30.8%,中度受害林分内有虫株率为44.3%,而重度受害林分内高达78.3%。根据变异函数曲线图分析得知:轻度受害林、中度受害林和重度受害林内褐梗天牛幼虫种群空间分布最优拟合模型分别为高斯模型、高斯模型和指数模型,成虫的种群空间分布最优拟合模型均为线性模型。在3种林分中褐梗天牛幼虫数量具有明显的空间依赖性,轻度受害林、中度受害林和重度受害林内幼虫数量的空间依赖范围分别是19.10、11.97、61.98m,其空间连续性强度分别是0.646、0.784和0.500;成虫的空间依赖范围分别是43.08、43.23、44.17m,其空间连续性强度分别是0.044、0.021和0.171,但其成虫的数量在空间呈随机分布,没有表现出空间依赖性。根据垂直分布图分析得出:褐梗天牛幼虫和成虫在油松上主要集中聚集在某个高,然后随着高度增加密度降低,随着高度接近地面密度也降低。用Kriging插值法生成的空间分布图显示幼虫在空间分布上具有明显的聚集性,其聚集中心主要集中在林地中心,由林地中心株向整个林地扩散,而成虫则表现为随机分布。     

Effects of Elasmopalpus lignosellus (Lepidoptera: Pyralidae) damage on sugarcane yield

Feeding by lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae), larvae on sugarcane (a complex hybrid of Saccharum spp.) causes leaf damage, dead hearts, and dead plants that can result in stand and yield loss. A 2-yr greenhouse experiment was conducted to examine sugarcane variety and plant age-specific feeding responses to E. lignosellus. Plants growing from single-eye setts of three varieties were exposed to a single generation of E. lignosellus larvae beginning at the three-, five-, and seven-leaf stages. Results indicated that the physical damage and resulting yield loss of plants attacked by E. lignosellus larvae were dependent on the variety and leaf stage at which they were infested. Significantly more plant damage was observed in all three varieties when infested at the three- than at the seven-leaf stage. Larvae caused significantly more plant damage and reduced yield in CP 89-2143 than in CP 78-1628. Tiller production increased in CP78-1628 and CP 88-1762 when infested at the three-leaf stage, whereas tiller production, biomass and sugar yield decreased in CP 89-2143 when infested at all leaf stages, compared with the untreated control. There was no reduction in yield when CP 78-1628 was infested at the three- or five-leaf stages. Biomass was reduced in CP 88-1762 when plants were infested at any of the leaf stages, but sugar yield was reduced only when infested at the seven-leaf stage. These results indicate that compensation in response to E. lignosellus damage was variety dependent and declined with the delay in infestation time.