Yellow Sticky Cards Research Articles

Population dynamics of Scirtothrips dorsalis (Thysanoptera: Thripidae) and other thrips species on two ornamental host plant species in Southern Florida.

Since its 2005 introduction into the United States, chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), has become a problematic pest of agronomic, vegetable, fruit, and ornamental plants. Knowledge of its population dynamics may help managers better monitor and control S. dorsalis. Population estimates were recorded for S. dorsalis and other thrips species on Knock-Out rose (Rosa 'Radrazz') and green buttonwood (Conocarpus erectus L.) from July 2007 to September 2008 in two field plots (one per plant species) in Homestead, FL. Yellow sticky card traps and samples of terminals, flowers, buds, and leaves were collected. S. dorsalis accounted for 95% of all thrips individuals collected from plants and 84% from traps with the remainder including at least 18 other thrips species. More thrips were caught on or flying near rose plants (47,438) than on or near buttonwoods (5,898), and on-plant densities of S. dorsalis appeared higher for rose than for buttonwood. Compared with rose leaves, rose buds, terminals, and flowers each had higher numbers of S. dorsalis, and buds and terminals had higher densities. On each host plant species, S. dorsalis density fluctuated over time with peaks in the late spring, summer, and fall, but populations were consistently low in the late winter and early spring. On roses, increased plant damage ratings correlated with reduced numbers of flowers and buds, reduced mean flower areas, and increased on-plant number and density of S. dorsalis. There were positive correlations over time between S. dorsalis density and plant damage rating for rose flowers (R = 0.78; P = 0.0003) and for buttonwood terminals (R = 0.90; P = 0.0001). Yellow sticky card traps were effective for monitoring S. dorsalis and may be especially useful and economically justified for the most susceptible hosts, but they also work well for less susceptible hosts. A good S. dorsalis scouting program should hence consider trap catches and symptoms such as leaf distortion, small flower area (size), and thrips population concentrations near buds and terminals.

Short communication. A survey of potential insect vectors of the plant pathogenic bacterium Xylella fastidiosa in three regions of Spain

The emergence of a rapid-spreading olive disease associated with Xylella fastidiosa in southern Italy represents a high risk to susceptible crops in other countries of the Mediterranean basin, if insect vectors occur in the region. The goal of this study was to identify xylem-feeding Auchenorrhyncha that could potentially act as vectors of X. fastidiosa in three regions of Spain (Andalucía, Murcia and Madrid). Samplings with sweep net and stem tap were carried out in October/2004 on grapevines and adjacent crops (olives, nectarine, citrus, Prunus spp.), ornamental trees and herbaceous weeds. Yellow sticky cards were placed in ten vineyards located across 100 km in Andalucía and in three vineyards distant 10-15 km apart in Murcia. Specimens of frequently-trapped species were tested by nested- or multiplex-PCR for the presence of X. fastidiosa. The Typhlocybinae leafhopper, Austroasca (Jacobiasca) lybica (Hemiptera: Cicadellidae) was the most abundant species in vineyards and citrus orchards. Planthoppers (Hemiptera: Fulgoroidea) and psyllids (Hemiptera: Psylloidea) were prevalent on olives. Cicadellinae leafhoppers (known as sharpshooters), which are major vectors of X. fastidiosa in the Americas, were not found in the samples. The only potential vectors were spittlebugs (Hemiptera: Cercopoidea) collected on Populus sp., herbaceous and on conifer trees (Pinus halepense); the spittlebug Neophileanus sp. was common on conifer trees adjacent to a vineyard in Jumilla. None of the insect samples tested positive for X. fastidiosa by PCR assays. However, spittlebugs already associated with susceptible crops in Spain may allow fast spread of X. fastidiosa in case this pathogen is introduced.

Efficacy and mechanisms of communication disruption of the red clover casebearer moth (Coleophora deauratella) with complete and partial pheromone formulations.

The red clover casebearer, Coleophora deauratella Leinig and Zeller (Lepidoptera: Coleophoridae), is a major pest of red clover (Trifolium pratense L.) grown for seed in Canada and parts of Europe. Insecticides are ineffective against C. deauratella, and other control methods, such as pheromone-mediated mating disruption, need to be explored. The efficacy and mechanisms of communication disruption were evaluated in small-plot trials (0.25 ha) with reservoir-type rope dispensers loaded with either the complete pheromone blend [10:1 ratio of (Z)-7-dodecenyl acetate: (Z)-5-dodecenyl acetate] or the major component alone [(Z)-7-dodecenyl acetate]. Both formulations reduced catches of male C. deauratella in pheromone traps (>99.6 %). In pheromone-treated plots, more males were caught on yellow sticky cards near dispensers that released the complete pheromone blend, than on cards near dispensers releasing the major component. In the laboratory, after pre-exposure to either the complete blend or the major component for 1 h, male C. deauratella antennae became adapted, as measured by electroantennograms conducted 5 min. after treatment. Adaptation due to pre-exposure to either formulation resulted in a shift in the pheromone response threshold; antennae from pre-exposed moths responded more strongly to high pheromone dosages (5-50 μg) than did antennae from untreated control moths. Antennae from moths held in clean air for 24 h after pre-exposure recovered and responded similarly to pheromone as antennae from control moths. These results suggest that both formulations have the potential to disrupt pheromone communication in C. Deauratella, but that the disruption mechanisms of the two formulations likely differ.

Survey of potential sharpshooter and spittlebug vectors of Xylella fastidiosa to grapevines at the São Francisco River Valley, Brazil

Survey of potential sharpshooter and spittlebug vectors of Xylella fastidiosa to grapevines at the Sao Francisco River Valley, Brazil. Pierce's disease of grapevines, caused by Xylella fastidiosa, is a serious problem in some regions of North America, not yet reported in Brazil. In this study, a survey of potential sharpshooter (Hemiptera, Cicadellidae, Cicadellinae) and spittlebug (Hemiptera, Cercopidae) vectors of X. fastidiosa was conducted in vineyards at the Sao Francisco River Valley, a major grape growing region in Brazil. Four vineyards of Vitis vinifera L. were sampled fortnightly from June/2005 to June/2007, using yellow sticky cards, each placed at two different heights (45 cm aboveground and 45 cm above the crop canopy) in 10 sampling localities. A total of 4,095 specimens of sharpshooters were collected, nearly all from 3 Proconiini species, Homalodisca spottii Takiya, Cavichioli & McKamey, 2006 (96.8% of the specimens), Tapajosa fulvopunctata (Signoret, 1854) (3.1%), and Tretogonia cribrata Melichar, 1926 (1 specimen). Hortensia similis (Walker, 1851) (2 specimens) was the only Cicadellini species. Only 1 cercopid specimen, belonging to Aeneolamia colon (Germar, 1821), was trapped. Even though they are not considered potential Xylella vectors, 2 Gyponini leafhoppers were collected: Curtara samera DeLong & Freytag, 1972 (11 specimens) and Curtara inflata DeLong & Freytag, 1976 (1 specimen). Homalodisca spottii was observed feeding and mating on green branches of grapevines, in addition to egg masses. Because of its prevalence on the crop canopy, occurrence throughout the year (with peaks from February to August), and ability to colonize grapevines, H. spottii could be an important vector if a X. fastidiosa strain pathogenic to grapevines becomes introduced at the Sao Francisco River Valley.

Visual Responses of Adult Asian Citrus Psyllid (Hemiptera: Liviidae) to Colored Sticky Traps on Citrus Trees

The effects of five differently-colored sticky traps in capturing adult Diaphorina citri were evaluated in citrus orchards. Trap catches of D. citri were monitored fortnightly on blue, green, red, white and yellow sticky cards placed on three citrus varieties during D. citri active flight period from April to July in south Texas. Evaluation of mean trap catches of each color by repeated measures analysis of variance produced three separate groups: yellow traps caught significantly more D. citri adults than the other four traps; red and green traps caught significantly more D. citri than blue and white traps, which were not significantly different. Although the number of adult psyllid captured on all trap types significantly increased with time during the trapping period, the performance of traps did not change with time. Trap catches were also significantly influenced by the citrus species; traps placed on lemon trees captured more D. citri than those placed on sweet orange and grapefruit, suggesting that plant preference exhibited by D. citri may influence the performance of traps. The ratio of trap reflectance between the 680 to 700 nm and the 450 nm was significantly correlated with total trap catches in all host species studied. Thus, this index was a good indicator of the attractiveness of adult D. citri to colored traps. Additionally, we compared the reflectance values of young versus mature flush shoots of the three host plants used in this study as related to densities of D. citri recorded in colored traps. We discussed the importance of visual cues in the host finding behavior of adult D. citri.

Insecticidal activity of Brassica juncea seed meal to the fungus gnat Bradysia impatiens Johannsen (Diptera:Sciaridae)

AbstractFungus gnats (Bradysia impatiens) can be a serious pest especially to plants grown in confined areas, and although various methods of control are available, safer and more effective control measures are desirable. Mustard seed meal, a by‐product remaining after oil removal for use as a biodiesel feedstock, contains compounds called glucosinolates that hydrolyse to insecticidal 2‐propenyl isothiocyanate. Our objective was to produce a dose‐response curve for making recommendations of Brassica juncea seed meal applications that will result in fungus gnat larvae control. Twenty colony‐raised fungus gnat larvae were added to 20 g (226 per cm3) of potting media, and adult emergence monitored during 2 weeks using yellow sticky cards. Treatments included without meal, detoxified meal and 19 doses ranging from 0.05 to 3.0 g seed meal. A logistic model was used to predict an LC50 of 0.18 and an LC90 of 0.38 g seed meal for the 20‐g pot. The amounts of seed meal required to produce the observed LC50 and LC90 were predicted to produce 0.08 and 0.17 μmol 2‐propenyl isothiocyanate per cm3 potting medium, respectively. B. juncea seed meal has potential utility for the control of B. impatiens, thus warranting additional studies to determine the seed meal's chronic impact on fungus gnats, phytotoxicity and plant fertility benefits.

Impacts of Bt Rice Expressing Cry1C or Cry2A Protein on the Performance of Nontarget Leafhopper,Nephotettix cincticeps(Hemiptera: Cicadellidae), Under Laboratory and Field Conditions

Transgenic rice expressing Bacillus thuringiensis Berliner (Bt) protein can effectively control target insects including stem borers and leaf folders. However, the potential effects of Bt rice on nontarget organisms including nontarget herbivores have not been fully evaluated. In the current study, ecological fitness parameters of the nontarget herbivore, Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae), fed on T1C-19 (Cry1C) or T2A-1 (Cry2A) rice were compared with non-Bt rice (MH63) under laboratory conditions. A 2-yr field trial was also conducted to monitor the population dynamics of N. cincticeps in the Bt and control rice plots using the vacuum-suction machine and yellow sticky card traps. Laboratory results showed that there were no significant differences in some of biological parameters including egg developmental duration, adult fresh weight, adult longevity, and oviposition period when N. cincticeps fed on Bt or non-Bt rice was compared. However, the survival rate of N. cincticeps nymphs fed on T2A-1 Bt rice plants was significantly higher than that on the control. When N. cincticeps fed on T1C-19 Bt rice plants, its nymphal duration was significantly longer and fecundity significantly lower compared with those fed on both T2A-1 Bt and non-Bt rice plants; the preoviposition period of N. cincticeps fed on T1C-19 and T2A-1 Bt rice was also significantly shorter than those on non-Bt rice. Nonetheless, both seasonal density and population dynamics of N. cincticeps adults and nymphs were similar between Bt (T1C-19 and T2A-1) and non-Bt rice plots under field conditions. In conclusion, our results indicate that our two tested Bt rice lines would not lead to higher population of N. cincticeps. Long-term experiments to monitor the population dynamics of N. cincticeps at large scale need to be carried out to confirm the current results.

Impact Assessments of Transgenic cry1Ab Rice on the Population Dynamics of Five Non-Target Thrips Species and Their General Predatory Flower Bug in Bt and Non-Bt Rice Fields Using Color Sticky Card Traps

A 2-yr field study was conducted to assess the effects of transgenic japonica rice (KMD1 and KMD2) with a synthetic cry1Ab gene from Bacillus thuingiensis Berliner on population dynamics and seasonal average densities of five thrips species including Stenchaetothrips biformis (Bagnall), Frankliniella intonsa (Trybom), F. tenuicornis (Uzel), Haplothrips aculeatus (Fabricius), Haplothrips tritici (Kurd) and their general predatory flower bug, Orius similis Zheng as compared to the parental control rice line using the white, blue and yellow sticky card traps. Population dynamics and seasonal average densities of these five thrips species and their general predatory flower bug were not significantly affected by rice type. Additionally, the white sticky card trap was suggested to be the most suitable for monitoring the population of these five thrips species and their general predator. These results show that our tested Bt rice lines do not interrupt the population of non-target thrips species and their general predatory flower bug in the field, and also cannot result in more occurrence of these thrips species in the rice ecosystem.

Development of an Insectary Plant Mixture for New Mexico and its Effect on Pests and Beneficial Insects Associated with Pumpkins

Abstract An insectary mixture of flowering annuals suitable for use in the high desert irrigated agriculture of New Mexico was developed over 3 years using pumpkins, Cucurbita moschata L., as a model cropping system. Plant establishment, survival, and flowering phenology were assessed in both clay and sandy soils by using weekly quadrat samples. Abundance of beneficial insects and spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber, were monitored with yellow sticky cards (Trece Inc., Adair, OK). Abundance of squash bug, Anasa tristis (DeGeer), was monitored weekly by sampling eggs and nymphs. Establishment of the flowering mixture was significantly better in clay than sandy soils in each of the 3 years. Of the fifteen plant species tested, California bluebell (Phacelia campanularia A. Gray), buckwheat (Fagopyrum esculentum Moench), dill (Anethum graveolens L.), Plains coreopsis (Coreopsis tinctoria Nuttall), garden cosmos (Cosmos bipinnatus Cavanilles), and sweet alyssum (Lobularia maritim...

Survival strategies of Dalbulus maidis during maize off‐season in Brazil

AbstractDespite the importance of Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae) as a vector of maize‐stunting pathogens, it is not understood how this leafhopper survives the maize off‐season in regions where overwintering hosts do not occur. We investigated migration and the use of alternate hosts as possible survival mechanisms for D. maidis during maize off‐season in Brazil. Dalbulus maidis populations were monitored with yellow sticky cards for 16–29 months in Anastácio (Mato Grosso do Sul State), in two farms with perennial pastures (Pasture1 and Pasture2), where maize had not been planted for >5 years, in a subsistence farm >20 km distant, where maize was annually planted (spring) (Maize1), and in Piracicaba (São Paulo State), where maize was grown year round (Maize2). RAPD‐PCR analysis of leafhoppers sampled on maize in two plots (Maize1 and Pasture1) at 15–20 and 110–120 days after germination was performed. Dalbulus maidis was trapped in the maize plots of all areas, but not in weedy or woody vegetation adjacent to the plots. Higher numbers were trapped throughout the year in Piracicaba, where maize was continuously grown under irrigation, and in the subsistence farm of Anastácio, where volunteer maize plants were available for long periods in the maize off‐season. In Anastácio farms, some population peaks were recorded in the absence of maize from midwinter to early spring, especially after soil plowing. RAPD‐PCR analysis showed that D. maidis populations sampled were genetically similar. Our data suggest that D. maidis uses a mixed strategy to survive the over‐season period in Brazil, in which part of the population overwinters locally on volunteer maize plants or nearby irrigated maize crops, whereas the other individuals migrate to colonize new maize crops in distant areas or regions. We hypothesize that immigrant D. maidis uses the contrast between plowed and vegetated soil as a visual cue for locating new maize crops.

Population Dynamics of the Beet Leafhopper (Hemiptera: Cicadellidae) in the Columbia Basin as Influenced by Abiotic Variables

ABSTRACT Beet leafhoppers (Circulifer tenellus Baker) have been identified as the vector for a plant-pathenogenic phytoplasma known as beet leafhopper-transmitted virescence agent. Beet leaf-hopper-transmitted virescence agent causes purple top disease in potatoes, which can reduce yields and tuber quality. A trapping network, composed of ≈100 sites, monitors leafhoppers in the Columbia Basin of Oregon and Washington through a collaborative effort of regional researchers and stakeholders. Yellow sticky cards were used to determine the timing and spatial distribution of beet leafhoppers in the Columbia Basin; insects were counted weekly from early April through late October in 2006, 2007, and 2008. Weather data collected from a network of weather stations in Oregon and Washington were used in a nonparametric multiplicative regression analysis to determine which abiotic environmental variables might influence beet leafhopper populations. Weather conditions (mean temperature, dew point, precipitation, and wi...

Local and landscape scale variables impact parasitoid assemblages across an urbanization gradient

Urbanization is a major driver of land cover change worldwide, yet little is known about how urbanization affects beneficial arthropod communities. This study examined how local and landscape scale variables associated with urbanization influenced parasitic Hymenoptera abundance and diversity in residential and commercial properties along a rural to urban landscape gradient in Wisconsin. At a landscape scale, 300 m surrounding sites, land cover percentages were calculated for five cover classes: impervious cover, forest, grassland, agriculture, and urban green space. In addition, habitat diversity (Simpson's index) was calculated for the landscape surrounding study sites. At a local scale (within the boundaries of an individual property), flower diversity, flower area, tree density, and hardscape were measured and related to parasitoid abundance and diversity. During 2006 and 2007, parasitoids were sampled twice a month June–August using yellow sticky cards. Parasitoid abundance was a positive function of flower diversity, a local scale variable. The positive relationship between parasitoid abundance and flower diversity only occurred in areas containing high to moderate levels of urban development, suggesting parasitoids locally benefited from the increased availability of floral resources in urban but not rural sites. Parasitoid diversity decreased as impervious cover increased in the surrounding landscape. Parasitoid diversity decreased by approximately 10% in highly urbanized sites relative to rural sites, a pattern driven by several parasitoid families not detected in urban sites. These results suggest conservation strategies that focus on landscape variables at multiple scales can play an integral role in preserving beneficial arthropods across urban landscapes.

Cicadomorpha Insects Associated With Bacterial Leaf Scorch Infected Oak in Central New Jersey

Potential insect vectors for transmission of oak leaf scorch caused by Xylella fastidiosa Wells et al., in pin and red oaks in New Jersey were surveyed by placing yellow sticky card traps in tree canopies and fogging with pyrethrin insecticide during 2002-2006. Thirty-seven Cicadomorpha species were collected from 20 genera in Membracidae, Cicadellidae, Aphrophoridae, and Clastopteridae. Of the 12,880 potential vectors collected, 91.4% were Membracidae, 6.9% were Cicadellidae, and 1.7% were Aphrophoridae and Clastopteridae. Fogging collected more insect species and individuals than sticky card collections. Sticky card sampling, done more frequently and at a larger number of locations provided similar community structure information as fogging. Sticky card collections of the dominant treehopper species, Ophiderma definita Woodruff were male biased when females were gravid. O. definita populations peaked in early June, comprised 68.2% of the total collection, and were more abundant in pin oaks than red oaks. Graphocephala versuta (Say) peaked in mid-July, comprising 6.2% of the total collection. Higher Cicadomorpha populations were observed in asymptomatic oak canopies than in neighboring X. fastidiosa infected oaks. Individual insect specimens collected from oaks were subjected to a X. fastidiosa DNA assay by polymerase chain reaction amplification. The average X. fastidiosa positive rate was 13.89% for all specimens tested. Eleven treehopper species, six leafhopper species, and four spittlebug species tested DNA positive for X. fastidiosa.

Evaluation of a modified sticky card to attract Bemisia tabaci (Hemiptera: Aleyrodidae) and a behavioural study on their visual response

Sticky cards with a yellow circle in black background originally developed to attract anthophilous thrips were also found to attract whiteflies. The potential of the new sticky cards for capture of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) was evaluated in oriental melon greenhouses in comparison with ordinary rectangular yellow sticky cards. Two types of the new sticky card (24W × 39L cm) were designed to contain either two large yellow circles (18D cm) or two small yellow circles (13D cm) in a black background on both sides. In each greenhouse, 18 sticky cards of each type were installed. The cards with small circles captured 1.8 times more B. tabaci per unit area than the rectangular yellow sticky cards. In the examination of on-site flight activity of B. tabaci, the cards with large circles attracted 70% of the B. tabaci that took off from the plant canopy. The card with small yellow circles captured 49% and the rectangular yellow sticky card captured 32%. In laboratory behavioural studies, sticky cards with different backgrounds and shapes were attached inside acrylic cages and B. tabaci on tomato leaves were released. Yellow sticky cards with a black background were 2.1 times more attractive than sticky cards with a green background, and triangular-shaped yellow sticky cards with a black background attracted 1.5 times more B. tabaci than those with squares. In conclusion, sticky cards with yellow circles in a black background attracted more B. tabaci per unit area than ordinary rectangular yellow sticky card, and thus could be an improvement for monitoring or managing B. tabaci.

Populational fluctuation of vectors of Xylella fastidiosa, wells in sweet orange [Citrus sinensis (L.) Osbeck] varieties of northwest Paraná State, Brazil

The aim of the present study was to assess the population flutuation of the sharpshooters species subfamily Cicadellinae belonging to the tribes Cicadellini and Proconiini, in sweet orange [Citrus sinensis( L). Osbeck] commercial orchards of the northwest region of Paraná State , Brazil. Samplings were carried out the employing every time 24 yellow sticky cards. Identification of the species showed that the most representative were Dilobopterus costalimai of the Cicadellini tribe and Acrogonia citrina of the Proconiini tribe.

Efeito da estrutura da paisagem e do genótipo de Eucalyptus na abundância e controle biológico de Glycaspis brimblecombei Moore (Hemiptera: Psyllidae)

Glycaspis brimblecombei Moore is an Australian native pest of Eucalyptus detected in Brazil in 2003. Since then, it has spread fast and colonized plantations in several states of the country. This study aimed to investigate the influence of cerrado remnants on the abundance and biological control of G. brimblecombei. We placed yellow sticky card traps to capture insects in four plantations of hybrid clones of Eucalyptus urophylla x Eucalyptus grandis ('Urograndis') and four plantations of E. urophylla x Eucalyptus camaldulensis ('Urocam'). Traps were placed in three areas of these plantations: center, border with cerrado and border without cerrado. We also collected leaves from the same clones to estimate psyllid egg and lerp abundance. The abundance of G. brimblecombei was lower in the plantation-cerrado border, and the inverse pattern was observed for microhymenopterans. The leaf abaxial surface showed a higher abundance of eggs and nymphs, probably as a consequence of a lower parasitism rate and mechanical removal by wind and rain. Egg number was higher on Urograndis than in Urocam clones, but the number of psyllid lerps was higher in the latter. Thus, the establishment of first instars is probably a critical event to psyllid infestation, and these differences may be caused by morphological, anatomical and biochemical leaf features of distinct clones. Our results suggest that the maintenance of native vegetation around plantations is a promising management practice to promote the natural biological control of G.brimblecombei, a strategy that would also enhance the preservation of cerrado remnants.

Multicolored Asian Lady Beetle (Coleoptera: Coccinellidae) Activity and Wine Grape Phenology: Implications for Pest Management

We determined the phenology of the multicolored Asian lady beetle, Harmonia axyridis (Pallas), adults in relation to the phenology of wine grapes (Frontenac and Marechal Foch) in Minnesota and Wisconsin vineyards to establish a management window for H. axyridis infestations in wine grapes. In addition, we also assessed the flight activity of H. axyridis in an agricultural landscape. The phenology of berry development and ripening was determined by recording berry size and sugar content of randomly selected berries. The phenology of H. axyridis was determined by tracking its flight activity with yellow sticky cards in vineyards and with a blacklight trap in an agricultural landscape. Berry development and ripening showed three distinct growth periods or phases. The end of growth period I averaged 9 July (Frontenac) and 11 July (Marechal Foch). Veraison, which marks the end of growth period II, averaged 25 July (Frontenac) and 3 August (Marechal Foch). Harvest, the third growth period averaged 18 September for Frontenac and 17 September for Marechal Foch. A major peak of H. axyridis captures occurred between veraison and harvest (i.e., the grape susceptible stage). A similar peak in the summer was observed in the agricultural landscape approximately 10 d before the major peak in the vineyards.

Levantamento populacional de cigarrinhas (Hemiptera: Cicadellidae) associadas à transmissão de Xylella fastidiosa em pomares cítricos do Litoral Norte da Bahia

The causal agent of citrus variegated clorosis, Xylella fastidiosa, is transmitted by leafhoppers of the subfamily Cicadellinae, whose species vary regionally. The goal of this study was to identify potential vectors of this pathogen in citrus groves of Bahia North Coast, Brazil. The survey was done from March/2002 to February/2003 in three seven- to nine-year-old sweet orange (Citrus sinensis, Pêra variety) groves located in Rio Real, BA. Fifteen yellow sticky cards (8.5x11.5 cm) were installed 40 m apart in each grove, hanged at 1.5 m high on the upper north side of citrus canopies, and replaced fortnightly. A sweep net was periodically used to sample leafhoppers on herbaceous weeds inside the groves, by selecting five points at random and performing 30 sweeps in each point. A total of 1,360 specimens of 49 Auchenorrhyncha species were collected in this study, mostly in the family Cicadellidae (90.2%). The subfamily Cicadellinae, which includes the sharpshooter vectors of X. fastidiosa, showed the largest number of species (14) and specimens (84.8%). Acrogonia flagellata Young, A. citrina Marucci & Cavichioli, Homalodisca spottii Takiya, Cavichioli & McKamey and an unidentified Cicadellini (species 1) were the dominant species trapped on citrus canopies, while Hortensia similis (Walker) and Erythrogonia dubia (Medler) were dominant in the weedy vegetation. Among the Cicadellinae species already known as vectors of X. fastidiosa in citrus, only A. citrina, Bucephalogonia xanthophis (Berg) e Ferrariana trivittata (Signoret) were found. The two latter species were accidentally trapped by sweep net in the weedy vegetation.

Impact of Reduced-Risk Insecticides on Soybean Aphid and Associated Natural Enemies

Insect predators in North America suppress Aphis glycines Matsumura (Hemiptera: Aphididae) populations; however, insecticides are required when populations reach economically damaging levels. Currently, insecticides used to manage A. glycines are broad-spectrum (pyrethroids and organophosphates), and probably reduce beneficial insect abundance in soybean, Glycine max (L.) Merr. Our goal was to determine whether insecticides considered reduced-risk by the Environmental Protection Agency could protect soybean yield from A. glycines herbivory while having a limited impact on the aphid's natural enemies. We compared three insecticides (imidacloprid, thiamethoxam, and pymetrozine,) to a broad-spectrum insecticide (lamda-cyhalothrin) and an untreated control using two application methods. We applied neonicotinoid insecticides to seeds (imidacloprid and thiamethoxam) as well as foliage (imidacloprid); pymetrozine and lamda-cyhalothrin were applied only to foliage. Foliage-applied insecticides had lower A. glycines populations and higher yields than the seed-applied insecticides. Among foliage-applied insecticides, pymetrozine and imidacloprid had an intermediate level of A. glycines population and yield protection compared with lamda-cyhalothrin and the untreated control. We monitored natural enemies with yellow sticky cards, sweep-nets, and direct observation. Before foliar insecticides were applied (i.e., before aphid populations developed) seed treatments had no observable effect on the abundance of natural enemies. After foliar insecticides were applied, differences in natural enemy abundance were observed when sampled with sweep-nets and direct observation but not with yellow sticky cards. Based on the first two sampling methods, pymetrozine and the foliage-applied imidacloprid had intermediate abundances of natural enemies compared with the untreated control and lamda-cyhalothrin.

Landscape composition influences patterns of native and exotic lady beetle abundance

AbstractAim Coccinellid beetles are important predators that contribute to pest suppression in agricultural landscapes. Since the introduction of the exotic coccinellids Coccinella septempunctata L. and Harmonia axyridis Pallas into the USA, several studies have reported a decline of native Coccinellidae in agroecosystems. We aimed to investigate the influence of landscape composition on native and exotic coccinellid abundance within soybean fields.Location Iowa, Michigan, Minnesota and Wisconsin.Methods As part of a 2‐year study (2005–06) on the biological control of the soybean aphid, Aphis glycines Matsumura, we examined coccinellid communities in 33 soybean fields using yellow sticky card traps. Landscape heterogeneity and composition were measured at multiple spatial scales ranging 1–3.5 km from focal soybean fields where coccinellid sampling took place.Results Exotic species made up 90% of the total coccinellid community in Michigan soybean fields followed by Wisconsin (84%), Minnesota (66%) and Iowa (57%). Harmonia axyridis was the dominant exotic coccinellid in all states comprising 45–62% of the total coccinellid community, followed by C. septempunctata (13–30%). Two additional exotic species, Hippodamia variegata (Goeze) and Propylea quatuordecimpunctata (L.) were also found in the region. Overall, the most abundant native coccinellid was Hippodamia convergens Guerin‐Meneville; however, its abundance varied across the region, comprising 0% (Michigan) to 28% (Iowa) of the total coccinellid community. Landscape structure significantly influenced the composition of coccinellid communities in soybean agroecosystems. We found that native coccinellids were most abundant in low‐diversity landscapes with an abundance of grassland habitat while exotic coccinellids were associated with the abundance of forested habitats.Main conclusion We propose that grassland dominated landscapes with low structural diversity and low amounts of forested habitat may be resistant to exotic coccinellid build‐up, particularly H. axyridis and therefore represent landscape‐scale refuges for native coccinellid biodiversity.