Environmental Entomology

Published by Entomological Society of America
Online ISSN: 0046-225X
Publications
Article
Traps baited with ethyl (E,Z)-2,4-decadienoate (pear ester) or (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) in two- or three-way combinations with the sex pheromone (E,E)-8,10-dodecadien-1-ol (codlemone) and acetic acid (AA) were evaluated for codling moth, Cydia pomonella (L.). All studies were conducted in apple orchards, Malus domestica Borkhausen, treated with sex pheromone dispensers during 2010. Septa were loaded with codlemone, DMNT, and pear ester individually or codlemone with either DMNT or pear ester together (combo lures). Polyethylene vials loaded with AA were added as a co-lure. Residual analyses of field-aged combo lures and weight loss of the AA co-lure were conducted. AA vials lost 50-150 mg wk(-1). Weekly weight loss was not affected by field aging, but was closely correlated with the daily mean temperature. Pear ester was released from septa at a slightly higher but nonsignificant rate than codlemone. DMNT was released at a significantly higher rate than codlemone, and lures were effective for 4 wk. The addition of codlemone to traps baited with either host plant volatile plus AA had either no effect or significantly increased total moth catches. The addition of AA significantly increased the catch of female moths with either combo lure. Total moth catches in traps baited with pear ester or DMNT combo lures and AA did not differ and were either significantly higher or similar to the pear ester combo lure. These data suggest that codling moth may be more effectively monitored in sex pheromone-treated orchards with multi-component lures, including codlemone, AA, and host plant volatiles.
 
Laboratory procedure outlining the steps followed during the experiment.  
Average F. candida body length by antibiotic treatment. Bars labeled with the same letter are not signiÞcantly different (ANOVA; P 0.0001). Multiple comparisons were made with the Ryan-Einot-Gabriel-Welsch multiple range test.  
Mean eggs laid and percent eggs hatched in each container per week by treatment 
Representative photographs of F. candida from experimental treatments. (A) Control. (B) Ampicillin. (C) Oxytetracycline. (D) Tylosin tartrate. Calibration bar is equal to 5,000 m.  
Test of representative individuals from the control and antibiotic treatments. Each lane is a PCR ampliÞcation from the DNA extraction of 5 individuals. (A) COII; (B) dnaA. Lanes: 1, 2 no antibiotic; 3, 4 tylosin; 5, 6 oxytetracycline ; 7, 8 ampicillin; 9, 10 F. candida-infected strain TNA; 11, negative control. Extra band in lane A8 is nonspeciÞc ampliÞcation.  
Article
Folsomia candida Willem (Isotomidae: Collembola) is an edaphic parthenogenetic species commonly used in ecotoxicity studies. We exposed F. candida to a high dose of three antibiotics, tylosin, ampicillin, and oxytetracycline, that target different bacterial groups. Possible toxic effects were assessed through egg production, hatching, and body size. All three antibiotics caused toxic effects. Treatment with oxytetracycline proved the most toxic. This group showed the smallest body size and lowest number of eggs laid, likely the result of a combination of antibiotic toxicity and avoidance of the antibiotic spiked food. Active toxin avoidance by F. candida in toxicological assays may play a role in minimizing their exposure to toxic compounds. Despite the administration of high doses of oxytetracycline, F. candida individuals remained infected with the intracellular bacteria Wolbachia indicating that this strain is resistant to this antibiotic or that the host or its gut flora had detoxified the compound. An increase in percent egg hatch with time was seen in the ampicillin and oxytetracycline treatments, indicating a possible accommodation of the host and/or gut-flora to these antibiotics.
 
Article
Cactoblastis cactorum Berg (Lepidoptera: Pyralidae), the cactus moth, is a well-known biological control agent of prickly pear cactus (Cactaceae: Opuntia Miller). The arrival of the moth in Florida and its subsequent spread through the southeastern United States poses a threat to opuntioid diversity in North America. Of particular concern are the ecological and economic impacts the moth could have in the southwestern United States and Mexico, where both native and cultivated Opuntia species are important resources. It is unknown which species would best support larval development if the moth were to spread further westward in North America. This study aimed to determine if ovipositing females demonstrate preferences for any of 14 common opuntioids native to or naturalized in Mexico and the southwestern United States; which of these opuntioids best support larval development; and if oviposition preference correlates with larval performance, as predicted by simple adaptive models. Results from a field experiment showed that female moths preferred O. engelmannii Salm-Dyck ex Engelmann variety linguiformis (Griffiths) Parfitt and Pinkava and O. engelmannii variety engelmannii for oviposition. A generalized linear model showed number of cladodes and degree of spininess to be significant predictors of oviposition activity. Results from a no-choice larval survival experiment showed Consolea rubescens (Salm-Dyck ex de Candolle.) Lemaire and O. streptacantha Lemaire to be the best hosts. Epidermal toughness was a significant predictor of most larval fitness parameters. In general, oviposition preference was not correlated with larval performance. A lack of co-evolutionary history between C. cactorum and North American opuntioid species may help explain this disconnect.
 
Article
To evaluate the potential of Bacillus thuringiensis (Bt) Cry1F protein accumulation in soil, transgenic corn containing event DAS-01507-1 encoding the cry1F gene was grown in three field sites for 3 consecutive yr, and the corn plants were incorporated into the soil through postseason tillage or no tillage each year. Soil samples were collected from these fields, and the level of Cry1F protein in these samples was determined using an enzyme-linked immunosorbent assay (ELISA) with a synthetic invertebrate gut fluid as an extraction buffer. The ELISA was validated in soil matrices over the concentration range of 18-180 ng/g dry weight, with a limit of detection of 4.5 ng/g dry weight. The assay was shown to have good accuracy and precision. No detectable Cry1F protein was found in any of the soil samples collected from the Cry1F corn fields. Soil also was bioassayed, and no biological activity was observed against Heliothis virescens neonates. These results indicate that the level of Cry1F protein accumulated in soil after 3-yr continuous planting of transgenic Cry1F corn is negligible.
 
Comparison of detection of CLs by pyrosequencing and traditional PCR
Article
Accurate detection and quantification of Candidatus Liberibacter solanacearum (CLs), the putative causal agent of zebra chip disease of potato (Solanum tuberosum L.), in the potato psyllid, Bactericera cockerelli (Sulc), has become necessary to better understand the biology of the disease cycle. Studies on the transmission efficiency of potato psyllids have shown inconsistencies with field surveys. There have also been reports of laboratory colonies inexplicably losing and regaining CLs infection as detected by polymerase chain reaction (PCR). Until now, DNA primers were used to detect CLs in potato psyllid tissue using conventional polymerase chain reaction (PCR) and gel electrophoresis or by real-time quantitative PCR. In this study, CLs was detected using bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) at levels identifiable by PCR, and low levels, including samples with only one cell of CLs. Potato psyllids with <300 pyrosequencing reads did not show positive using conventional PCR. These results indicate that the currently accepted PCR diagnostic technique produces false negatives due to detection limits higher than what is generally present in field collected psyllids, and also provides an explanation as to why laboratory colonies seem to lose and regain CLs infection.
 
Article
Aphids harbor a community of bacteria that include obligate and facultative endosymbionts belonging to the Enterobacteriaceae along with opportunistic, commensal, or pathogenic bacteria. This study represents the first detailed analysis of the identity and diversity of the bacterial community associated with the cabbage aphid, Brevicoryne brassicae (L.). 16S rDNA sequence analysis revealed that the community of bacteria associated with B. brassicae was diverse, with at least four different bacterial community types detected among aphid lines, collected from widely dispersed sites in Northern Britain. The bacterial sequence types isolated from B. brassicae showed little similarity to any bacterial endosymbionts characterized in insects; instead, they were closely related to free-living extracellular bacterial species that have been isolated from the aphid gut or that are known to be present in the environment, suggesting that they are opportunistic bacteria transmitted between the aphid gut and the environment. To quantify variation in bacterial community between aphid lines, which was driven largely by differences in the proportions of two dominant bacterial orders, the Pseudomonales and the Enterobacteriales, we developed a novel real-time (Taqman) qPCR assay. By improving our knowledge of aphid microbial ecology, and providing novel molecular tools to examine the presence and function of the microbial community, this study forms the basis of further research to explore the influence of the extracellular bacterial community on aphid fitness, pest status, and susceptibility to control by natural enemies.
 
Article
The impact of weather variables on Culex pipiens L. (Diptera: Culicidae) population dynamics in the Po Valley, Northern Italy, a densely populated region containing the largest industrial and agricultural areas in Italy, was investigated. Monitoring of mosquitoes was carried out by using CO2-baited traps without light, collecting data weekly from 1700 to 0900 hours during the period May-September, from 1997 to 2011. Daily minimum, average, and maximum relative humidity; daily minimum, maximum, and average temperature; rainfall; and hydroclimatic balance (rainfall-potential evapotranspiration) were obtained from three weather stations within the surveillance zone. The average population dynamic trend over the 15-yr period showed a bell-shaped curve with a major peak in June and a secondary peak at the end of August in the rural areas, whereas bimodality was not evidenced in the urban areas. The correlation analyses showed that the mosquito seasonal population and the population in the period of maximum West Nile virus circulation (August-September) was mostly affected by the relative humidity registered from March to July, particularly in May, and, to a lower extent, also by hydroclimatic balance registered in April-July, and by the rainfall occurred in June-July. In addition, the rate of increase of the population during the spring months influenced the development of the mosquito population of the following months.
 
Article
Ethyl (E,Z)-2,4-decadienoate (pear ester) is known to be a kairomonal attractant for both male and female codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae). Electroantennographic (EAG) studies were conducted to investigate the sensitivities of codling moth, the chestnut torticid species Cydia fagiglandana (Zeller), Cydia splendana (Hübner), and Pammene fasciana L., and the green budmoth Hedya nubiferana Haworth to pear ester. The attractiveness of this compound to the different species was tested in several field-trapping experiments conducted in Italy. The EAG responses of the different tortricids species were dose-dependent. The field-trapping experiments confirmed the attractiveness of the compound to codling moth; similar activity was also shown on the chestnut tortricids in their respective host plant environment.
 
Article
The diagnostic dose for temephos susceptibility test was established based on Aedes aegypti, the susceptible Bora (French Polynesia) strain, for practical and routine use. The diagnostic dose was subsequently used to evaluate the susceptibility/resistance status in F1 progenies of field-collected samples from Bangkok and various parts of Thailand. It appeared that Ae. aegypti mosquitoes of one collection site each in Bangkok, Nakhon Sawan (northcentral), and Nakhon Ratchasrima (northeast) were resistant to temephos, with mortality ranging from 50.5 to 71.4%. Moreover, there was a trend of resistance to temephos among Ae. aegypti populations of all studied districts of Nakorn Ratchasima and most areas of Nakhon Sawan, of which those in one area were susceptible. However, various levels of temephos susceptibility were found in Bangkok populations, including resistance and incipient resistance. In Chonburi Province (eastern), all mosquitoes were susceptible to temephos with an indication of tolerance in one sample. Additionally, mosquitoes from Songkhla (south), Chiang Rai (north), Kanchanaburi (west), and Chanthaburi (east) remained susceptible to temephos during the sample collecting period. Bioassay tests on Aedes albopictus populations collected in this study from Nakhon Sawan, Nakorn Ratchasima, Songkhla, and Kanchanaburi revealed high susceptibility to temephos. Although the use of temephos seems to be potentially effective in many areas of the country, a noticeable trend of resistance indicated that alternative vector control methods should be periodically applied.
 
Article
Certain biotypes of the Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex cause extensive damage and are important pests and virus vectors in agricultural crops throughout the world. Among the most invasive and well studied are the B and Q biotypes. Recent reports in Shandong Province, China, have indicated that the Q biotype was introduced there in approximately 2005, whereas the B biotype has been established there for approximately 10 yr. Even so, the present distribution of the two biotypes in Shandong has not been examined. The results of this study showed that the B and Q biotypes are both present in Shandong Province based on bar-coding using a approximately 450-base fragment of the mitochondrial cytochrome oxidase I (mtCOI) gene. In addition, a B biotype-specific polymerase chain reaction primer pair that amplifies a approximately 300 bp mtCOI fragment was designed and used to examine the biotype composition of B. tabaci in selected crops from six provincial locations, using the general mtCOI primers as an internal positive control for DNA quality. The results of this study indicated that the Q biotype was the predominant B. tabaci colonizing all of the crops in the study sites examined. This suggests that the Q biotype has displaced the B biotype in Shandong Province of China, which until now was the predominant biotype. This is the first report of the displacement of the B by the Q biotype in field grown crops in China, and in a locale where neither the B nor the Q biotype is native. We hypothesize that this phenomenon may have been exacerbated by the widespread use of neonicotinoid insecticides for whitefly control, given the sustained efficacy thus far of neonicotinoids against the B biotype, and their failure at times to effectively control the Q biotype.
 
Article
Helicoverpa armigera is an important lepidopteran pest of cotton in China. From 2002, the frequency of Bt resistance alleles and quantitative shifts in larval Cry1Ac tolerance of field H. armigera population were monitored using bioassays of F(1) and F(2) offspring of isofemale lines from Xiajin County of Shandong Province (an intensive Bt cotton planting area) and Anci County of Hebei Province (a multiple-crop system including corn, soybean, peanut, and Bt cotton) in northern China. During 2006-2008, a total of 2,306 isofemale lines from the Xiajin population and a total of 1,270 isofemale lines from the Anci population were successfully screened on Cry1Ac diets. For each year, it was estimated that the major resistance gene frequency in Xiajin population in 2006, 2007, and 2008 was 0, 0.00022, and 0.00033, respectively. No major alleles conferring resistance to Cry1Ac were found in the Anci population; the frequency of resistance alleles for Cry1Ac was 0. Based on the relative average development rates (RADRs) of H. armigera larvae in F(1) tests, no substantial increase in Cry1Ac tolerance was found in either location over the 3-yr period. There were also significantly positive correlations between RADR of lines in the F(1) generation and the RADR of their F(2) offspring, indicating genetic variation in response to toxin. The low frequency of resistance alleles found in this study and in our previous results from 2002 to 2005 suggest the frequency of resistance alleles has remained low and that natural refugia resistance management strategy maybe effective for delaying resistance evolution in H. armigera to Bt cotton in northern China.
 
Size and location of southern pine beetle samples from five national forests in Mississippi
Summary statistics for southern pine beetle from five national forests in Mississippi
Pairwise estimates of F ST (below diagonal) and the DAS genetic distance estimates (above diagonal) among national forests in Mississippi
Article
The southern pine beetle, Dendroctonus frontalis Zimmerman, is the most destructive insect pest of pine forests in the southeastern United States, Mexico, and Central America. Southern pine beetle aggressively attacks pine trees, and when in epidemic stages, they are capable of killing even the most healthy pine trees in a short period of time. Despite the amount of destruction caused by the southern pine beetle and the amount of monetary loss faced by the timber industry and recreation, the population genetics of this species has been limited to comparisons among distant geographic locations. This study investigates the fine-scale genetic population structure of the southern pine beetle in Mississippi. Very little genetic differentiation was observed among samples. Bayesian assignment testing failed to detect multiple groups within all samples; estimates of genetic differentiation and genetic distance were very low in magnitude; and a Mantel test did not reveal a significant relationship between genetic distance and geographic distance. These results suggest that management of the southern pine beetle needs to consider the potential movements of individuals within and among national forests and should be focused on a large scale, at least as big as continuously forested areas and possibly even multiple forests. These results further suggest that removal of beetle-infested trees is important.
 
Article
The squash bug, Anasa tristis (De Geer), is a major indigenous pest of Cucurbita species across the United States and a vector of cucurbit yellow vine disease. The seasonal phenology of the squash bug in central Kentucky and its natural enemies were studied using summer squash planted sequentially throughout the 2005 and 2006 growing seasons. The squash bug was first detected on 5 June 2005 and 3 June 2006. In both years, peak numbers of all squash bug stages occurred in July and August. Our field data, substantiated by published degree-day models for squash bug development, suggest one complete and a partial second generation of squash bugs in 2005 and one complete generation of squash bugs in 2006. The most abundant ground-active predators in squash fields included Araneae, Carabidae, Staphylinidae, and Geocoridae. Coleomegilla maculata (De Geer) and Geocoris punctipes (Say) were the most abundant foliage-inhabiting predators. Direct field observations of predators feeding on squash bugs or their eggs included G. punctipes, Pagasa fusca (Stein), and Nabis sp. The parasitoids Trichopoda pennipes (Fabricius) and Gyron pennsylvanicum (Ashmead) were found also. Squash bug egg masses were monitored to determine predation and parasitism rates in the field. In four studies during 2005 and 2006, predation rates were low (7% or less), and parasitism ranged from 0 to 31%. Overall, squash bug egg mortality increased as the season progressed.
 
(A) Graphic depiction of bacterial proÞles from D. valens beetles. Representations contain OTUs selected to best explain community patterns of association (left) and OTUs that were not good predictors of community patterns of association (right) as determined by BvSTEP. The dendrogram clustered bacterial proÞles according to SorensenÕs similarity index performed on all OTUs detected from DGGE. Sequenced OTUs are listed in Table 1. (B) Dendrogram from group average cluster analysis of bacterial community similarity across beetles from each site. (Online Þgure in color.)
Article
Bacterial communities are known to play important roles in insect life histories, yet their consistency or variation across populations is poorly understood. Bacteria associated with the bark beetle Dendroctonus valens LeConte from eight populations, ranging from Wisconsin to Oregon, were evaluated and compared. We used the culture-independent technique of denaturing gradient gel electrophoresis to visualize bacterial diversity, or individual operational taxonomic units (OTUs), from individual beetles. One-way analysis of similarities was used to test for differences of bacterial communities between sites. Analysis of community profiles showed that individual beetles on average contained 10 OTUs, with frequency of association from 2 to 100% of beetles. OTU sequences most closely matched beta- and gamma-proteobacteria, and one each matched Bacilli and Actinobacteria. Several OTUs were particularly abundant, most notably an Actinobacterium from 100% and two Proteobacteria from 60% of beetles sampled. Some OTUs were similar to previously described bacteria with known biochemical capabilities and ecological functions, suggesting that some bacterial associates of D. valens may contribute to its ability to exploit a resource low in nutrients and high in defensive compounds. There were significant differences of bacterial communities between sites. The strength of these differences was positively correlated with distance between sites, although additional unexplained factors also contribute to the variation.
 
Article
The glassy-winged sharpshooter, Homalodisca vitripennis (Germar), is an invasive pest that has spread across the southern and western United States. H. vitripennis is highly polyphagous and voracious, feeding on at least 100 plant species and consuming up to 100 times its weight in xylem fluid daily. The insect is a vector of the phytopathogen Xylella fastidiosa (Wells), which is the causative agent of Pierce's disease in grapevines. To evaluate the microbial flora associated with H. vitripennis, total DNA extracts from hemolymph, alimentary canal excretions, and whole insect bodies were subjected to 16S rDNA pyrosequencing using the bTEFAP methodology and the resulting sequences (370-520 bp in length) were compared with a curated high quality 16S database derived from GenBank http://www.ncbi.nlm.nih.gov. Species from the genera Wolbachia, Delftia (formerly Pseudomonas), Pectobacterium, Moraxella, Serratia, Bacillus, and many others were detected and a comprehensive picture of the microbiome associated with H. vitripennis was established. Some of the bacteria identified in this report are initial discoveries; providing a breadth of knowledge to the microbial flora of this insect pest can serve as a reservoir of information for developing biological control strategies.
 
Loadings of the principal components of behavioral and location variables 
Design of no-choice cross experiments. 
Longitudinal changes in miteÕs behavior during experiments of 80-h duration. Lines are smooth functions Þtted to percentages of females expressing given type of behavior. RR, QQ, control groups (reared on familiar host); RQ, QR, treatment groups (reared on novel host). 
Results of fitting GEE model to nonacceptance be- havior on Lolium population data 
Results of fitting GEE model to nonacceptance be- havior on Elymus population data 
Article
For phytophagous arthropods, host acceptance behavior is a key character responsible for host plant specialization. The grain rust mite, Abacarus hystrix (Nalepa), is an obligately phytophagous, polyphagous eriophyid mite recorded from at least 70 grass species. In this study, the hypothesis that two host populations of this mite (one collected from quackgrass and the other from ryegrass) are highly host-specific was tested using behavioral data. For this purpose, female behavior when exposed to familiar and novel host plants was observed in no-choice cross experiments. Altogether, 13 variables were used to describe mite behavior. Data were subjected to principal component analysis, and host acceptance behavior was subsequently tested with generalized estimating equations (GEE). Distinct variation in female behavior between familiar and novel hosts was observed. Females from neither population accepted novel hosts. This was recorded as significant differences in the occupation of and overall activity on particular plant parts. On their familiar host, females were not active and showed little tendency to move. On novel hosts females were more active and mobile, spending more time walking, running, and climbing on the whole plant surface and showing a tendency to disperse. Other differences in behavior between studied populations were also observed. Thus, the results suggest that mites of these two studied populations (1) differ in their behaviors during plant exploitation and (2) can quickly distinguish between their familiar host and an unfamiliar host used by a conspecific. These findings support the hypothesis of narrow host specialization of ryegrass and quackgrass populations of this highly polyphagous species.
 
Article
Thirteen plant species were tested for their suitability as hosts for Abagrotis orbis (Grote), a climbing cutworm pest of grapevines in British Columbia. Choice tests were also conducted to investigate larval feeding preferences for the Brassicaceae species joi choi, Brassica rapa variety. Chinensis L., spring draba; Draba verna L.; and shepherd's purse, Capsella bursa-pastoris (L.) Medik; compared with postdormant buds of grape, Vitis vinifera L. (Vitaceae), and leaves of nine other plant species from several families. Results showed that tah tsai, Brassica rapa L. variety rosularis (M. Tsen & S. H. Lee) Hanelt (Brassicaceae), is a superior host for A. orbis based on shorter time to adult eclosion, heavier pupae, and higher rates of survival. Later-instar larvae died when fed draba, whereas those reared on shepherd's purse did not survive beyond the third instar. White clover, Trifolium repens L. (Fabaceae), and grape leaves were unsuitable hosts throughout development. Fifth-instar A. orbis preferred plants of the Brassicaceae family, dandelion, Taraxacum officinale Weber (Asteraceae), and strawberry, Fragaria sp. L. (Rosaceae), compared with postdormant grape buds. The results of this study suggest that the winter annual mustards draba and shepherd's purse that often grow abundantly in vine rows might help reduce climbing cutworm damage to the buds of grapevines.
 
Brief descriptions of N. pygmaea habitats surveyed in eight areas of South Korea
Descriptive statistics and MANOVA test for DS and PDS environmental variables
Article
To characterize habitats of Nannophya pygmaea Rambur (the northern pygmyfly; Odonata: Lilbellulidae), which is endangered in Korea, we analyzed characteristics of surface water and soil, landscape properties, and vegetation types in 22 habitats in eight areas of Korea where nymphs of N. pygmaea have been found since 2005. We divided the habitats into two groups: DS (dwelling site) habitats, where N. pygmaea was observed at the time of the study, and PDS (past dwelling site) habitats, where N. pygmaea recently lived but is no longer found. The habitats were mostly located in former paddy fields on mountain slopes that have been abandoned for 3-7 yr. The main water sources for these habitats were ground water and surface runoff, and the water level was stable at 3-7 cm in depth. The habitats ranged from 300 to 1000 m(2) and were dominated by Juncus effusus, which formed tussock mounds. According to the hydrosere model of succession, N. pygmaea appeared mostly in the early stages of plant succession (the period approximately 3-7 yr after the initiation of succession in former paddy fields) and N. pygmaea preferred habitats displaying the water and soil characteristics that are typical of the early stages of succession in abandoned paddy fields. These results indicate that the primary habitats of N. pygmaea in Korea are recently abandoned paddy fields that are in an oligotrophic state. As succession proceeds in these habitats, N. pygmaea disappears. A habitat management program should be launched to conserve the habitats and populations of N. pygmaea.
 
Article
The tropical root weevil, Diaprepes abbreviatus (L.), has been a pest of citrus and ornamental plants since its introduction into Lake County, FL, in 1964. Since then, it has colonized the Florida peninsula to the south of its point of introduction but has not expanded its range to the north. A lower threshold for oviposition by D. abbreviatus was estimated as 14.9 degrees C. Eggs were highly susceptible to cold, with 95% mortality (LTime95) occurring in 4.2 d at 12 degrees C. Relative susceptibility of life stages to cold was eggs > pupae > larvae > adults. Archived weather data from Florida were examined to guide a mapping exercise using the lower developmental threshold for larvae (12 degrees C) and the lower threshold for oviposition (15 degrees C) as critical temperatures for mapping the distribution of D. abbreviatus and the potential for establishment of egg parasitoids. Probability maps using the last 10 yr of weather data examined the frequency of at least 10, 15, 20, 25, or 30 d per winter when soil temperature was <or=12 degrees C. The geographic area that experienced between 15 and 20 d per winter with mean daily soil temperature <or=12 degrees C closely approximated the northern limit of D. abbreviatus in Florida. Homologous maps of Arizona, California, and Texas predict the areas where soil temperatures favor establishment of D. abbreviatus. Successful establishment of egg parasitoids in Florida seems to be limited to southern Florida, where mean daily air temperatures fall below 15 degrees C <25 d/yr. By this measure, we predict that egg parasitoids will not establish in Arizona, California, or Texas.
 
Estimated development parameters for D. abbrevia- tus reared on diets that satisfy target values for survival and weight
Article
The root weevil Diaprepes abbreviatus L. has been continuously reared since 1992 on an artificial diet (F1675) first reported in 1982. The weight of weevils reared on F1675 was more than twice as great as field-collected individuals. Recently, several ingredients included in the original F1675 diet were shown to have little or no effect on insect performance. We examined the effects of varying three ingredients of a simplified diet on the weight of adult D. abbreviatus. We used a geometric design combined with response surface models to evaluate the effects of the amount and proportion of diet ingredients to identify optimal diet recipes for normative weight gain defined in relation to field-collected D. abbreviatus from locations in Florida. Our results showed that it is possible to produce adults of normative weight or, for that matter, any mean weight within a wide range by varying the proportions of cottonseed meal, wheat germ and cellulose, a non-nutritive filler. Although wheat germ contributed to greater weight gain, survival of larvae to adult was lower on diets containing only wheat germ compared with diets containing only cottonseed meal as the principal nutritive components. The analyses of all the variables measured indicate that cottonseed meal is the only major nutritive component, in addition to standard vitamin and salt mixes, required to produce adult D. abbreviatus of normative weight.
 
Article
The reproductive biology of Fidiobia dominica Evans (Hymenoptera: Platygastridae) was studied in the laboratory (25.6 +/- 1 degrees C) using host eggs of Diaprepes abbreviatus L. (Coleoptera: Curculionidae). F. dominica readily parasitized D. abbreviatus eggs on both host plant and wax paper substrates. The number of egg masses parasitized and the number of offspring produced were higher when females were offered more than one host egg mass but did not differ when either two or three egg masses were offered. Female parasitoids that were provided with host eggs and a honey food source lived significantly longer than those that were not provided a food source; however, they did not parasitize more D. abbreviatus eggs. Oviposition occurred in host eggs from 0 to 7 d old, and host mortality was relatively consistent for eggs 0-5 d old and lower for eggs 6-7 d old. Successful parasitoid emergence seldom occurred after host eggs were 4 d old, and by 7 d, no adults successfully emerged. Developmental time from egg to adult was 19.3 +/- 0.2 d for males, significantly more rapid than the females (20.4 +/- 0.1 d). The mean longevity of adult females was 8.0 +/- 0.4 d, with a mean oviposition period of 2.7 +/- 0.3 d; males survived 8.1 +/- 0.4 d. The demographic parameters including intrinsic rate of increase (r(m)), generation time (T), and net reproduction (R(o)) were 0.142/d, 22 d, and 22.4 female eggs/d, respectively.
 
Trichome density and leaf thickness of six host plants of D. abbreviates (N 10, means SEM) 
Effect of host plant on successful parasitism of D. abbreviatus eggs by H. sperata. No-choice tests on six host plants and control treatment (wax paper). Different letters represent signiÞcant differences (P 0.05; ANOVA, TukeyÕs studentized range test); error bars represent SE. 
Article
Diaprepes abbreviatus L. is a highly polyphagous root weevil that causes damage to several fruit crops, ornamental plants, and other naturally occurring plants in Florida. Haeckeliania sperata Pinto is a gregarious endoparasitoid that attacks D. abbreviatus eggs. We hypothesized that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus. Six host plants with varying degrees of pubescence were used to determine the effect of leaf trichomes on the searching behavior and success of parasitism by H. sperata. No-choice tests showed that H. sperata was able to parasitize Diaprepes eggs laid on the six host plants. However, the plants with a high trichome density on their leaves had a lower percent of parasitism than the plants with smoother leaves. Removing trichomes from a host plant showed that the presence of some leaf trichomes had a negative effect on the overall searching efficiency of H. sperata. The presence of trichomes decreased the total distance traveled and increased the total search time of H. sperata females, resulting in a lower searching speed. Multiple regression analysis was used to establish the relationship between percent parasitism and leaf trichome density, leaf thickness, and the searching speed of H. sperata. Searching speed was the best predictor of percent parasitism; this parameter could be used to predict the suitability of host plants for the establishment of H. sperata. Our findings suggest that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus.
 
Survival (lx) (solid line) and age-speciÞc fecundity rate (m x ) (dashed line) of females of K. aberrans at different temperatures.  
Two-way ANOVA on factors (sex and temperature) affecting developmental time within each developmental stage of K. aberrans
Estimated parameters and predicted thresholds for nonlinear Lactin's model describing the relationship between temperature (°C) and developmental rate of all immature stages of K. aberrans reared on Typha sp.
Article
Development, survival, and reproduction of the predatory mite Kampimodromus aberrans Oudemans were studied at constant temperatures in the range from 15 to 35 degrees C under laboratory conditions. Larval developmental rate for both males and females increased gradually from 15 to 35 degrees C and decreased at higher temperatures. Lactin's nonlinear model described with adequate accuracy the relationship between developmental rate and temperature. The model predicted that lower and upper threshold temperatures for preimaginal development ranged from 9.8 to 11.8 degrees C and from 37.2 to 39.8 degrees C, respectively. The intrinsic rate of population increase (rm) at the different temperatures ranged from 0.0442 to 0.1575, with the highest value recorded at 25 degrees C. At 33 degrees C a negative rm value was estimated. The rm values determined at different temperatures were fitted to Lactin's nonlinear model, and the lower and upper threshold and the optimal temperatures for population increase were 10.5, 32.4, and 27.6 degrees C, respectively. These data indicate that K. aberrans may be better adapted to intermediate temperatures around 27 degrees C and, therefore, could be a useful biocontrol agent of spider mites during spring and early summer when such temperatures are prevalent in northern Greece. The results could also be useful in developing a population model for K. aberrans under field conditions.
 
Presence of oribatid mite species (Acari: Oribatida) from lichen and branch tip microhabitats associated with A. amabilis and T. heterophylla trees at Mt. Cain, Vancouver Island, British Columbia, Canada 
Article
To study the oribatid mite community inhabiting microhabitats in the canopy of montane Abies amabilis [(Douglas ex D. Don) Lindl.] and Tsuga heterophylla [(Raf.) Sarg] tree species across five elevational sites, we collected 180 branch tips and 180 foliose/crustose lichen samples over three time periods. Thirty-three species of oribatid mites were identified from the study area. Mite species richness and abundance was significantly affected by microhabitat, and this association was independent of sampling time. At the microhabitat scale, distinct species assemblages were associated with lichen and branch tip habitats, and to a lesser degree, tree species. Conifer specificity was most apparent in the closely related species of Jugatala, where Jugatala tuberosa Ewing was only found on branch tips from A. amabilis and Jugatala sp. was primarily found on branch tips from T. heterophylla. Microhabitat specificity was most pronounced in Dendrozetes sp. where most individuals were found on branch tips and Anachiperia geminus Lindo et al. that occurred primarily on lichens. Principal components analysis of oribatid mite community composition further showed a high degree of association with microhabitat and tree species. Habitat profiles are difficult to discern for many species because tree, microhabitat, and elevation preferences confound distribution patterns. Given the significant tree-microhabitat associations in species composition in this montane canopy study, we suggest that sampling multiple microhabitats across elevations to look for patterns in community structure offers opportunities to explicitly test organizing principles in community ecology.
 
Article
A series of field trials were used to assess the practicality of using sticky traps to monitor populations of green spruce aphid, Elatobium abietinum (Walker), in plantations of Sitka spruce. The highest numbers of alate E. abietinum were caught on sticky traps placed in the upper third of the live canopy at 9-17 m above the ground, whereas low numbers of aphids were caught just below the live canopy or at 2 m above the ground. Trials in 2005 with sticky traps of different colors showed that significantly more alate E. abietinum were caught on yellow, red, and green sticky traps than on white, blue, and black traps. A repeat trial in 2007 resulted in significantly more alate aphids being caught on red sticky traps than on traps of any other color except for green. Attraction to red is unusual among aphids, as aphids are thought not to possess a red-sensitive photoreceptor. The attraction of E. abietinum to red-colored sticky traps suggests that conifer-feeding aphids might have a fundamentally different color response compared with aphids that live on cereals, grasses, or herbaceous plants. Alternatively, the attraction to red might be a physiological artifact related to the presence of red-screening pigments in the aphid's compound eye.
 
Behavioral activities on balsam fir trees of spring and summer adults and larvae of the coccinellids A. mali and H. axyridis in a Christmas tree plantation
Article
The exotic coccinellid Harmonia axyridis (Pallas) recently expanded its range into eastern Canada and elsewhere in North America. We hypothesized that this coccinellid should be less well adapted to the prey Mindarus abietinus Koch. on balsam fir trees than the native coccinellid Anatis mali (Say), which evolved in close association with aphids on conifers in North America. We compared, under field conditions, prey use by both species by collecting data on their synchrony with M. abietinus, their prey searching and predation behaviors, life stage distribution in fir canopy, and their overall reproductive success in this system. The seasonal life cycle of A. mali was better synchronized with that of M. abietinus compared with that of H. axyridis. In spring, A. mali adults appeared nearly 2 wk earlier on trees than H. axyridis and were active predators of the aphid fundatrices. A. mali oviposition thus began before the aphid population started to grow, and its larvae were most active during peak aphid colonies. Behavioral observations showed that both adults and larvae of the native A. mali searched for prey more actively than those of H. axyridis. Distribution of life stages also showed that eggs and pupae had different distributions on trees and that the adult-to-adult net reproductive rate of A. mali was three times higher than that of H. axyridis. Thus, the native A. mali was better adapted than H. axyridis to prey on M. abietinus, possibly because it evolved for a much longer period of time with this prey in conifer habitats.
 
Article
Eupelmus vuilleti (Crawford) is an ectoparasitoid of the seed-eating beetle Bruchidius atrolineatus (Pic), which is an important pest of stored cowpea, Vigna unguiculata Walp, seeds in West Africa. Herein, we investigated the dispersal abilities of females within columns of seeds to assess the potential of E. vuilleti as a biological control agent of bruchids in cowpea granaries. The influence of host presence together with the 2 abiotic factors light and gravity on parasitoid movement and parasitization efficiency were analyzed. E. vuilleti females were able to travel through large seed masses and parasitize hosts located at the end of the seed column opposed to their introduction zone. Parasitoid movement was stimulated by light. E. vuilleti females exhibited a negative geotropism. Females introduced at the bottom of the seed column dispersed more and parasitized more hosts than females introduced at the top. Host presence had some influence on the dispersal of the parasitoids within the seed column at a host density of 10 infested seeds for 16,000-18,000 uninfested seeds. This depended on female introduction zone because gravity was the major factor influencing dispersal. The possible applications of these results for biological control of bruchids in cowpea granaries are discussed.
 
Circadian rhythm of ßight activity. One hundred females of F. arisanus are constantly present in the Þeld cage with a glued, ßy-infested orange fruit. Evolution per hour of captures, temperature, humidity, and barometric pressure mean data. No captures were recorded during the night (2000Ð0600 hours). 
Circadian rhythm of parasitism activity. Twenty females of F. arisanus were offered a ßy-infested banana every 2 h. Evolution per 2 h of parasitism, temperature, and humidity mean data. 
Inßuence of starvation on foraging motivation. Proportions of starved and fed females recaptured by a honey-baited trap rather than a host kairomone-baited trap (means 95% CI). Stars indicate a signiÞcant difference between treatments.
Article
Climatic conditions and the physiological state of a parasitoid may alter its host selection behavior and thus its efficiency as a biological control agent. We studied the influence of these parameters on the behavior of Fopius arisanus (Sonan), an egg-pupal parasitoid of many Tephritidae. In the first experiment, we assessed in field cage assays the influence of temperature, humidity, light intensity, barometric pressure, and wind speed. Both flight and parasitism were mainly affected by temperature and humidity. However, because these two factors were strongly correlated in our experiments, the direct influence of each one cannot be specified. Flight activity was affected by variations in barometric pressure. In a second set of experiments, we conducted release and recapture assays with dyed insects to determine the influence of sex, mating status, egg load, age, and starvation on attraction toward infested fruit. Males were not attracted, suggesting that fruit are not a mating site. The egg load seemed to be a major parameter of foraging motivation. Finally, we showed that flight activity strongly decreased after 48 h of starvation. We observed a possible switch to food in the foraging motivation of starved females, but this result was impaired by poor recoveries: <10% of released females were recaptured after 96 h of starvation. We finally discuss the importance of these observations on the efficiency of F. arisanus as a biological control agent in tropical humid areas.
 
Phototactic response of male and female emerald ash borer in dual-choice arena.  
Article
The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an exotic woodborer first detected in 2002 in Michigan and Ontario and is threatening the ash resource in North America. We examined the effects of light exposure and girdling on green ash (Fraxinus pennsylvanica Marsh) volatile production, and effects of light exposure, girdling, and leaf age on emerald ash borer adult feeding preferences and phototaxis. Green ash seedlings grown under higher light exposure had lower amounts of three individual volatile compounds, (Z)-3-hexenol, (E)-beta-ocimene, and (Z,E)-alpha-farnesene, as well as the total amount of six detected volatile compounds. Girdling did not affect the levels of these volatiles. Emerald ash borer females preferred mature leaves, leaves from girdled trees, and leaves grown in the sun over young leaves, leaves from nongirdled trees, and leaves grown in the shade, respectively. These emerald ash borer preferences were most likely because of physical, nutritional, or biochemical changes in leaves in response to the different treatments. Emerald ash borer females and males showed positive phototaxis in laboratory arenas, a response consistent with emerald ash borer preference for host trees growing in sunlight.
 
Location of transgenic and control pines (Þlled squares) from which invertebrate samples were collected within a 15 36-m transgenic pine Þeld trial. Open squares indicate trees not surveyed (distances between trees 3 m).  
Cumulative number of species observed for the following: (a) the total number of samples; (b) the number of samples for each collecting date; and (c) each treatment. Species curves were produced using the software Primer v 6.1.11 with 999 permutations.  
Percentage of abundance for total invertebrate taxa collected from the Þeld trial during October 2006/2007 and April 2007/2008. The numbers above bars are the total number of individuals per order, and the corresponding numbers of RTUs are in brackets.  
Tree diameter (cm) for transclones and control trees at each sampling event (n 118).  
Multidimensional scaling plots showing the similarity in species composition among treatments. Species composition on individual trees is plotted at each sampling event for the following: (a) total invertebrate species, (b) lepidopteran larval species, and (c) hemipteran species. The plots are based on nonstandardized square-root-transformed abundance data and binomial deviance dissimilarity.  
Article
As part of an investigation into the potential unintended ecological impacts of transgenic trees, invertebrates were sampled from a field trial of transgenic Pinus radiata D. Don carrying the expressed antibiotic resistance marker gene neomycin phosphotransferase II (nptII) along with other genes known to affect reproductive development in plants and from nontransformed control trees. Invertebrate species abundance, richness, diversity, and composition were measured and compared among trees of five different transclones and nontransformed isogenic control trees. Invertebrates were sampled at six-monthly intervals over a period of 2 yr. In total, 19,162 individuals were collected comprising 279 invertebrate recognizable taxonomic units. Total invertebrate populations as well as populations of herbivorous lepidopteran larvae and Hemiptera were compared among transgenic and control trees. The results show that the transclones had no significant unintended influence on species abundance, richness, diversity, or composition for all populations investigated.
 
Article
We tested the possibility that a lepidopteran leafminer, Coptotriche japoniella Puplesis and Diskus, inhibits the host plant Eurya japonica Thunberg from abscising mined leaves prematurely to increase its survivorship in immature stage. We monitored abscission patterns of mined leaves with sacrificed larvae, mined leaves with living larvae, and unmined leaves from April to July 2004 and 2005 until leafminers emerged as adults. Unmined leaves rarely abscised before July. Mined leaves with sacrificed larvae fell at a constant rate after May, abscising significantly more than unmined leaves. In contrast, mined leaves with living larvae rarely fell before adult emergence; afterward they abscised rapidly. We also examined larval/pupal survivorship and mortality sources on the ground and trees after leafminers completed larval development. Leafminers on the ground suffered a higher mortality from predation than those on trees, and thus they emerged as adults on the ground less successfully. These findings suggest that the leafminer C. japoniella prevents the host plant from abscising mined leaves prematurely until adult emergence, thereby increasing their survivorship.
 
Numerical sampling design for estimating density at three levels of relative precisions D 0 : (A) C. italicus and (B) Chorthippus/Euchorthippus . 
Binomial sampling design for estimating density of C. italicus at three levels of relative precisions D 0 : (A) sample size related to cage sampler occupancy rate and (B) sample size related to density. 
Simulation of the numerical sampling design for estimating density of C. italicus on validation plots (P1ÐP6) at three levels of relative precisions (D 0 ). (A) Estimated means in black compared with the validation plot mean in white. (B) Precisions really reached calculated as D s/n. (C) Sample size. (D) Sampling time.
Simulation of the binomial sampling design for estimating density of C. italicus on validation plots (P1ÐP6) at two levels of relative precisions (D 0 ). (A) Estimated means (white triangle and white diamond) compared with the validation plot mean (white square). (B) Occupancy rates. (C) Sample sizes. (D) Sampling times. Sample sizes and sampling times simulated with numerical sampling design with D 0 set to 0.35 are added for comparison (black diamond).
Simulation of the numerical sampling design for estimating density of Chorthippus/Euchorthippus on validation plots (P1ÐP6) at three levels of relative precisions (D 0 ). (A) Estimated means in black compared with the validation plot mean in white. (B) Precisions really reached calculated as D s/n. (C) Sample size. (D) Sampling time.
Article
Sampling methods to estimate acridid density per surface area unit in grassland habitats were compared using presence-absence data and count data. Sampling plans based on 6 yr of surveys were devised to estimate the density of Chorthippus spp., Euchorthippus spp., and Calliptamus italicus L. These acridids represented >90% of species in the study area. Sampling plans based on count data provided a reasonable tool when densities were >1/m(2) and when the level of precision was 0.20-0.30. A binomial sampling plan can be used to estimate C. italicus density with a level of precision >or=0.28. Sampling characteristics, i.e., estimated mean, actual precision, and sample size, were established on validation data sets with bootstrapping analysis. Sampling costs were also calculated according to density-dependent functions. Comparison between binomial sampling and enumerative sampling of C. italicus showed that binomial sampling required less time than enumerative sampling when densities were <or=2/m(2) and when fixed precision was >0.35. Plot area had no significant effect on sample variances of counts.
 
Article
In recent years, several attractant pheromones have been identified for cerambycid beetles, including 2-(undecyloxy)-ethanol (hereafter monochamol) for Monochamus galloprovincialis (Olivier), M. alternatus Hope, and M. scutellatus (Say). This study screened eight known cerambycid pheromones or their analogues (including monochamol) as potential attractants for M. carolinensis Olivier and M. titillator (F.), in the presence and absence of the host volatile α-pinene. Monochamol attracted M. carolinensis in the presence and absence of α-pinene, whereas M. titillator was only attracted to the combination of monochamol and α-pinene. (2R*,3R*)-2,3-Hexanediol also attracted both M. carolinensis and M. titillator, but only in the presence of α-pinene. Subsequent coupled gas chromatography-mass spectrometry and gas chromatography-electroantennogram detection analyses of extracts of volatiles collected from both sexes demonstrated that male M. carolinensis and M. titillator release monochamol, and that antennae of males and females of both species detect it. These results indicate that monochamol is a male-produced pheromone for both M. carolinensis and M. titillator.
 
Article
The response of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) to different emission rates of its pheromone, (3E, 8Z, 11Z)-tetradecatrienyl acetate, was measured in two greenhouse trials with traps baited with mesoporous dispensers. For this purpose, weekly moth trap catches were correlated with increasing pheromone emission levels by multiple regression analysis. Pheromone release profiles of the dispensers were obtained by residual pheromone extraction and gas chromatography quantification. In the first trial carried out in summer 2010, effect of pheromone emission was significant as catches increased linearly with pheromone release rates up to the highest studied level of 46.8 μg/d. A new trial was carried out in spring 2011 to measure the effect of the emission factor when pheromone release rates were higher. Results demonstrated that trap catches and pheromone emission fitted to a quadratic model, with maximum catches obtained with a release level of 150.3 μg/d of (3E, 8Z, 11Z)-tetradecatrienyl acetate. This emission value should provide enhanced attraction of T. absoluta and improve mass trapping, attract-and-kill, or monitoring techniques under greenhouse conditions in the Mediterranean area.
 
Relationship between the proportion of parasitized T. absoluta per plant by the parasitoid P. dignus against T. absoluta density in four tomato crops representing different cropping conditions, located in the surroundings of La Plata, Buenos Aires province, Argentina. (a and b) Sites 1 and 2, respectively; both are conventional greenhouses, 2004. (c) Site 3, organic open Þeld, 2005. (d) Site 4, organic greenhouse, 2005. (e) All sites combined. SE: slope of logistic regression curve. *SigniÞcant level: P 0.05.
Spatial distribution of P. dignus at three spatial scales in four tomato crops
Regression analysis of the probability of parasitism of T. absoluta larvae parasitized by P. dignus on host density at three spatial scales in four tomato crops
Regression analysis of risk of parasitism of T. absoluta larvae parasitized by P. dignus on host density at three spatial scales in four tomato crops
Article
We examined the interaction between the tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a key pest of tomato crops in South America, and its main solitary larval parasitoid, Pseudapanteles dignus (Muesebeck) (Hymenoptera: Braconidae). The pattern of parasitism of T. absoluta by the parasitoid was studied at three scales on tomato crops: plant, leaf, and leaflet. Host density, spatial distributions of both host and parasitoid, percentages of parasitism, variation in the probability and risk of parasitism in relation to host density, and the spatial density dependence were assessed in a horticultural region in Argentina. The spatial distribution of T. absoluta was clumped at all sites and scales, whereas that of P. dignus was much more variable, fitting to negative, positive binomial distributions and to Poisson series. Percentages of parasitism were as follows: site 1, 17.06%; site 2, 27.53%; site 3, 26.47%; site 4, 45.95%. Parasitoid aggregation in relation to host density was found at leaf and leaflet scales. However, the proportion of parasitized hosts was independent of host density. The variability of parasitism rates exhibited at the three spatial scales seems to result in partial refuges for the host, which might contribute to the persistence of the interaction between host and parasitoid. We discuss our field observations in relation to ecological theory and its potential application to the biological control of T. absoluta on tomato.
 
Article
Laboratory studies were conducted to measure selected life history traits and the functional response of the parasitoid Pseudapanteles dignus (Muesebeck), a major enemy of Tuta absoluta (Meyrick) in tomato crops in South America. Newly mated P. dignus females were individually exposed to 10 host larvae in mines for 24 h. We determined developmental time from egg to pupal formation and pupal stage duration, female adult life span, fecundity, reproductive period, daily parasitism rate, and sex ratio of offspring. For the functional response experiment, treatments consisted of six host densities: 3, 5, 7, 10, 15, 20, or 30 larvae. The number and proportion of parasitized hosts were calculated for each density. The shape of the functional response curve was analyzed by logistic regression. P. dignus females attacked hosts daily, exhibiting modest lifetime fecundity (approximately 32 parasitized hosts per female) and a female-biased offspring sex ratio. Female adult life span was 36 d. P. dignus showed a type I functional response within the range of host densities tested. We observed that females detect and parasitize the host within a wide range of densities, including low densities. The functional response curve reached an asymptote at a mean density of six hosts per day and seemed not to be egg-limited. Percent parasitism was approximately 30%. The ecological implications of the results in relation to the potential of P. dignus for the biological control of T. absoluta in tomato are discussed.
 
Article
The presence of arbuscular mycorrhizal fungi (AMF) influences plant nutrient uptake, growth, and plant defensive chemistry, thereby directly influencing multi-trophic interactions. Different fungal isolates (genotypes of the same fungal species) have been shown to differ in nutrient uptake ability. Plants infected with different AMF genotypes may vary in foliar nutrient or defensive chemical levels, potentially influencing multi-trophic interactions. Using a completely randomized design, we compared the effect of two isolates of the mycorrhizal fungus Glomus etunicatum W. N. Becker & Gerdemann on silver leaf whitefly (Bemisia argentifolii Bellows & Perring) (Hemiptera: Aleyrodidae) and parasitic wasp (Eretmocerus eremicus Rose & Zolnerowich) (Hymenoptera: Aphelinidae) abundance. Whitefly populations were not influenced by AMF infection. Parasite populations were higher on plants infected with the isolate collected from Georgia, even after controlling for whitefly abundance and plant architecture. We propose that AMF indirectly influences parasite abundance and parasitism through a change in leaf surface chemicals that affect parasitic wasps. Because of the ubiquity of and genetic variation in AMF, multi-trophic interactions are likely to be strongly influenced by belowground processes.
 
Article
Two synthetic sex pheromones have been developed and are currently used to detect the flight of the pecan nut casebearer, Acrobasis nuxvorella Neunzig, the most damaging pest of pecan [Carya illinoinensis (Wangenh.) K. Koch]. One pheromone (referred to as standard) is attractive to moths in the southern United States, but not in Mexico. The other pheromone (referred to as Mexican) is attractive to moths in the southern United States and in Mexico. These two pheromones have been implemented by producers as an important tool in monitoring the activity of this pest and have allowed for more efficient pesticide use. In the future, these pheromones could be used as a means of population reduction through pheromone based control methods. Trapping data taken over a 3-yr period were used to determine if phenological differences exist between pheromone types of pecan nut casebearer. The relative abundance of each pheromone type at several locations in the United States also was evaluated. Results of this study indicate that no phenological differences exist between the two pheromone types studied in the United States and that significantly more males are attracted to field-deployed pheromone traps baited with the standard pheromone than to traps baited with the Mexican pheromone.
 
Article
Temperature has strong effects on metabolic processes of individuals and demographics of populations, but effects on ecological communities are not well known. Many economically and ecologically important pest species have obligate associations with other organisms; therefore, effects of temperature on these species might be mediated by strong interactions. The southern pine beetle (Dendroctonus frontalis Zimmermann) harbors a rich community of phoretic mites and fungi that are linked by many strong direct and indirect interactions, providing multiple pathways for temperature to affect the system. We tested the effects of temperature on this community by manipulating communities within naturally infested sections of pine trees. Direct effects of temperature on component species were conspicuous and sometimes predictable based on single-species physiology, but there were also strong indirect effects of temperature via alteration of species interactions that could not have been predicted based on autecological temperature responses. Climatic variation, including directional warming, will likely influence ecological systems through direct physiological effects as well as indirect effects through species interactions.
 
Number of traps monitored in each county where commercial vineyards were surveyed for xylem ßuid-feeding Hemiptera in central Texas.
Nonparametric estimate of the time effect (smooth curve) with 95% conÞdence bands (dashed curves) for H. vitripennis.
Estimates of the time effects for H. vitripennis counts inside and outside vineyards.
Estimated percent change in the average between inside and outside traps for H. vitripennis (P 0.05).
Nonparametric estimate of the time effect (smooth curve) with 95% conÞdence bands (dashed curves) for G. versuta.
Article
A survey of xylem fluid-feeding insects (Hemiptera) exhibiting potential for transmission of Xylella fastidiosa, the bacterium causing Pierce’s disease of grapevine, was conducted from 2004 to 2006 in the Hill Country grape growing region of central Texas. Nineteen insect species were collected from yellow sticky traps. Among these, two leafhoppers and one spittlebug comprised 94.57% of the xylem specialists caught in this region. Homalodisca vitripennis (Germar), Graphocephala versuta (Say), and Clastoptera xanthocephala Germar trap catches varied significantly over time, with greatest counts usually recorded between May or June and August and among localities. A comparison of insect counts from traps placed inside and outside vineyards indicated that G. versuta is always more likely captured on the vegetation adjacent to the vineyard. C. xanthocephala was caught inside the vineyard during the summer. Between October and December, the natural habitat offers more suitable host plants, and insects were absent from the vineyards after the first freezes. H. vitripennis was caught in higher numbers inside the vineyards throughout the grape vegetative season. However, insects were also caught in the habitat near the affected crop throughout the year, and residual populations overwintering near vineyards were also recorded. This study shed new light on the fauna of xylem fluid-feeding insects of Texas. These results also provide critical information to vineyard managers for timely applications of insecticides before insect feeding and vectoring to susceptible grapevines. RÉSUMÉ: Cette étude, réalisée entre avril 2004 et mai 2006, a pris place dans la région viticole de Hill Country au centre du Texas et a examiné les insectes phytophages du xylème qui sont vecteurs potentiels de la bactérie Xylella fastidiosa responsable de la maladie de Pierce de la vigne. Dix neuf espèces d’hémiptères ont été collectées sur de pièges jaunes collants, parmi lesquels, deux cicadelles et un cercope constituaient 94.57% des spécialistes du xylème de cette région. L’abondance de Homalodisca vitripennis (Germar), Graphocephala versuta (Say) et Clastoptera xanthocephala Germar variait significativement à travers le temps, leurs maxima ayant été enregistrés entre mai ou juin et août, ainsi qu’entre les différentes localités. La comparaison des comptes d’insectes des pièges situés dans le vignoble et ceux placés en dehors indiquait que G. versuta est toujours plus souvent piégé près de la végétation qui borde le vignoble. Clastoptera xanthocephala a été piégé dans la vigne durant la période estivale alors qu’entre octobre et décembre, l’habitat naturel offre plus de plantes hôtes convenables. Cette espèce est absente après les premiers gels. Homalodisca vitripennis est capturé en beaucoup plus grands nombres à l’intérieur des vignobles durant toute la saison végétative de la vigne. Cependant, cet insecte est aussi piégé toute l’année dans l’habitat proximal de la culture affectée et des populations résiduelles hivernant près des vignobles ont aussi été détectées. Cette étude enrichit notre niveau de connaissance de la faune connue des insectes suceurs du xylème du Texas Central. Les résultats sont aussi critiques aux viticulteurs en ce qui concerne l’application bien ciblée d’insecticide avant l’exploitation et la transmission de la maladie par les insectes aux vignes susceptibles.
 
Mean abundance (overall, Cicadellini, Empoascini, Scarini, and Scarini morphospecies 1) and richness (tribes and morphospecies) of leafhoppers in coffee agroecosystems during the dry and wet season. Error bars show SE. 
Species accumulation curve for all leafhoppers sampled with elevated pan traps in a coffee agroecosystem. Error bars (95% CIs) are shown with thin lines around the observed morphospecies richness values. 
Conditional inference tree showing factors that correlate with (a) leafhopper abundance, (b) leafhopper morphospecies richness, and (c) leafhopper tribe richness in coffee agroecosystems. SigniÞcant predictors of leafhopper abundance are shown in circles in hierarchical ranking starting with the highest correlation to the dependent variable. P values indicate the signiÞcance of the relationship being tested. Numbers beneath the circles indicate thresholds over or under which data divided into signiÞcantly different values. Box plots include the inner quartiles (gray box), the median values (solid black line), and 1.5 times the inner quartiles (error bars) of leafhopper abundance associated with each string of predictor variables. Plots at each terminal node show median abundance of leafhoppers in each category and the number of pan trap locations (n) in each category. 
Article
Coffee agroecosystems with a vegetatively complex shade canopy contain high levels of biodiversity. However, as coffee management is intensified, diversity may be lost. Most biodiversity studies in coffee agroecosystems have examined predators and not herbivores, despite their importance as potential coffee pests and coffee disease vectors. We sampled one abundant herbivore group of leafhoppers on an organic coffee farm in Chiapas, Mexico. We sampled leafhoppers with elevated pan traps in high- and moderate-shade coffee during the dry and wet seasons of 2011. The two major objectives were to 1) compare leafhopper abundance and richness during the wet and dry seasons and 2) examine the correlations between habitat characteristics (e.g., vegetation, elevation, and presence of aggressive ants) and leafhopper richness and abundance. We collected 2,351 leafhoppers, representing eight tribes and 64 morphospecies. Leafhopper abundance was higher in the dry season than in the wet season. Likewise, leafhopper richness was higher in the dry season. Several vegetation and other habitat characteristics correlated with abundance and richness of leafhoppers. The number of Inga trees positively correlated with leafhopper abundance, and other significant correlates of abundance included vegetation complexity. Leafhopper richness was correlated with the number of Inga trees. As leafhoppers transmit important coffee diseases, understanding the specific habitat factors correlating with changes in abundance and richness may help predict future disease outbreaks.
 
The number of P. papatasi generations per year, starting date of successive generations, and generation time under semifield conditions at Giza, Egypt
Productivity and longevity of P. papatasi second generation reared under semifield conditions at Giza, Egypt
Article
The monthly density of the sand fly, Phlebotomus Papatasi Scopoli (Diptera: Psychodidae), was monitored during 2009 at Burg El-Arab, a rural district located close to the Mediterranean coast of Egypt. The number of annual generations and the efficacy of microbial control by the entomopathogenic fungus, Metrahizium anisopliae (Metsch.) Sorok (Ma79), were determined in the laboratory under atmospheric conditions, simulating those of the animal shelters in the study area. We used two collecting techniques; CDC light traps and oiled paper traps, to quantify sand fly density inside houses and in the open field. Adult flies exhibited a seasonal range from April to December. The seasonal pattern was bimodal, with one peak in July and the second one in October. Calculations of the correlation coefficient (r) revealed a significant role of temperature and relative humidity in the monthly abundance of the sand flies in the study area. P. papatasi colony completed seven annual generations under semifield conditions, but the mean developmental time of each immature stage and the mean total duration of development from egg to adult for each generation varied according to the prevailing temperature. The longest generation time was observed in winter (the mean ± SD was 118 ± 11.70 d), and the shortest one occurred at the highest temperatures in summer (the mean ± SD was 25.21 ± 2.04 d). In microbial control studies, the entomopathogenic fungus, M. anisopliae, was used at 15 × 10(8) spores/g food as a standard dose against the second-instar larvae of P. papatasi at the different seasons during 2009. Mortality reached 100% in winter and decreased to 56.0% as the prevailing temperature increased during the summer season.
 
Field plot arrangement for the relay-intercropped and monoculture sorghum.  
Pairwise Bray-Curtis coefficient of similarity (%) between lady beetle communities in alfalfa, cotton, diverse sorghum, and monoculture sorghum determined by sticky traps 
Article
Creating conditions that enhance the abundance of resident populations of natural enemies in agroecosystems is considered critical to the efficiency of biological control of insect pests. We conducted a study to determine the potential of relay-intercropping for enhancing the abundance of aphidophagous lady beetles in sorghum. A relay-intercropping system consisting of alfalfa, winter wheat, and cotton as intercrops and sorghum as a main crop was compared with sorghum monoculture plots at two study sites in OK from 2003 to 2006. Lady beetles and aphids were sampled throughout the season using sticky traps and field counts on individual sorghum plants. Results from sticky traps and field counts show that differences in abundance and species composition of lady beetles between intercropped and monoculture sorghum were not statistically different during each year of study. Also, the lady beetle-greenbug ratios in relay-intercropped and monoculture plots were not significantly different. Lack of significant effects of relay-intercropping in our study may have been attributable to the confounding effects of spatial and temporal scale and the low number of aphids and other alternative prey in the intercrops compared with high incidence of corn leaf aphids in sorghum early in the season.
 
Article
Phoridae (Diptera) have widespread impacts on insect communities by limiting host ant behavior. However, phorid-ant interactions may vary with habitat or environmental conditions. Three Pseudacteon species parasitize Azteca instabilis Fr. Smith, a common ant in coffee agroecosystems, and limit A. instabilis foraging, indirectly benefiting other insects. However, little is known about how phorid abundance, behavior, and effects change with environmental conditions. In shaded coffee systems, coffee (Coffea arabica L.) grows under a range of shade conditions and management changes affect species interactions. For example, Pseudacteon spp. more strongly limit A. instabilis foraging in low-shade coffee habitats. We sampled relative abundance of three phorid species around A. instabilis nests in three coffee habitats varying in shade management during dry and wet seasons. We measured canopy cover, tree richness, tree density, leaf litter depth, and number of nearby trees with A. instabilis to determine whether these habitat factors correlate with phorid abundance. P. laciniosus Brown was the most abundant phorid in both seasons. Phorid relative abundance did not differ by habitat, but did differ by season. P. laciniosus accounted for a higher proportion of phorids in the wet season (91.4%) than in the dry season (78.9%), and P. planidorsalis Brown accounted for a larger percent in the dry season (21.1%) than in the wet season (7.3%). Phorid composition did not differ with habitat type, and none of the measured environmental variables correlated with changes in phorid composition. Thus, phorids in coffee agroecosystems respond to large seasonal differences, but not differences between coffee habitats.
 
Article
Icerya purchasi Maskell is a polyphagous scale pest of ornamentals and several other crops. It has two natural specialist enemies that maintain its populations at low levels: Rodolia cardinalis (Mulsant) and Cryptochaetum iceryae (Williston). I. purchasi was recently observed in blueberry crops (Vaccinium corymbosum L.) in Argentina. Seven blueberry fields located in different agricultural landscapes were sampled from July 2006 to September 2008. I. purchasi was present only in the citrus areas of Gobernador Castro, San Pedro, and Concordia. In the last locality, it was present in January 2007, and the abundance was very low. In Buenos Aires, I. purchasi was more abundant in Gobernador Castro where it was present throughout all study period. In San Pedro, it was only registered in August 2007 and March, April, and June 2008. In Gobernador Castro, where the abundance was highest, the dominant crop near blueberries is citrus. The low abundance in San Pedro and Concordia fields may be attributable to the replacement of citrus crops by nonhosts. In Concordia and San Pedro fields, no parasitized I. purchasi were found. In Gobernador Castro, the proportion of adults parasitized was 0.805 +/- 0.286. When the risk of parasitism was analyzed for three density categories, there were no significant differences. R. cardinalis was present only in Gobernador Castro, and very few individuals were observed. The presence and abundance of I. purchasi in blueberry crops in Argentina seems to be linked to the structure of the landscape at the regional level, and the variable incidence of C. iceryae suggests major constraints to the scale's population growth.
 
The study area and sites with land cover change. The study area is represented by the rectangle (a), land cover in 1975 (b), and in 2001 (c). The ranges of the study sites (AM, GN) were shown in the study area (b and c). The ranges of the study sites cover the area extending 1 km from the survey route.
Study dates at the study sites
Number of individuals of butterßy species that were collected or counted at the GN and AM sites. The species were arranged according to species rank.
Mean of the values of abundance change of the groups of butterßy species. The bars indicate the SE. Figures of the GN site (a) and the AM site (b) according to distribution patterns, including those of the GN site (c) and the AM site (d) according to habitat types. The same letters on the bars indicate that the means do not differ signiÞcantly between the groups ( P Ͼ 0.5). N, northern species; M, miscellaneous; S, southern; FI, forest inside; FE, forest edge; GL, grassland. 
Mean of the values of abundance change according to habitat types for each distribution pattern for the GN (a) and AM (b) sites. The bars indicate the SE. Same letters on the bars indicate that the means do not differ signiÞcantly between the groups ( P Ͼ 0.5). N, northern species; M, miscellaneous; S, southern; FI, forest inside; FE, forest edge; GL, grassland. 
Article
In the Republic of Korea, most denuded forest lands have been restored since the 1960s. In addition, the annual mean temperature in the Republic of Korea has increased approximately 1.0 degrees C during the last century, which is higher than the global mean increase of 0.74 degrees C. Such rapid environmental changes may have resulted in changes in the local butterfly fauna. For example, the number of butterflies inhabiting forests may have increased because of reforestation, whereas the number of butterflies inhabiting grasslands may have declined. Furthermore, the number of northern butterflies may have declined, whereas the number of southern butterflies may have increased in response to global warming. Therefore, we compared current data (2002 approximately 2007) regarding the abundance of butterfly species at two sites in the central portion of the Korean Peninsula to data from the late 1950s and early 1970s for the same sites. Changes in the abundance rank of each species between the two periods were evaluated to determine whether any patterns corresponded to the predicted temporal changes. The predicted changes in butterfly abundance were confirmed in this study. In addition, the results showed a different response to habitat change between northern and southern species. In northern butterfly species, butterflies inhabiting forests increased, whereas those inhabiting grasslands declined. However, the opposite was true when southern butterfly species were evaluated. Changes in the abundance indicate that habitat change may be one of the key factors related to the survival of populations that remain around the southern boundary of butterfly species.
 
Crops and landscape features adjacent to the sites where 9-trap arrays were monitored weekly 
Article
The sampling range of pheromone traps for the navel orangeworm Amyelois transitella (Walker) (Lepidoptera: Pyralidae) and its association with abundance was investigated by examining mutual interference within cross-shaped arrays of nine wing traps baited with virgin females and placed at 400-m intervals in three 256-ha blocks of almonds (Prunus dulcis [Miller] D. A. Webb), and three of pistachios (Pistacia vera L.). The proportions of males captured in the different positions were compared with the mean males for all traps, used as an index for abundance. For means between zero and 50 males per trap per week, the distribution was unequal between trap positions and the greatest proportion of males were captured in the northern-most trap (i.e., the within-row direction). Between 50 and 100 males per trap per week, most males were captured in the western-most traps and fewest in the center, and proportions were equal in other trap positions. Above 100 males per trap per week, the proportion of males captured was more nearly equal for all trap positions. These results demonstrate that the sampling range of pheromone traps for navel orangeworm is density dependent and, at low densities, is >400 m. They also indicate that abundance affects the impact of direction (orientation) of trap interference. At low density, female-strength pheromone traps sample males from beyond the block in which they are placed for orchard blocks of <50 ha.
 
Article
Phenology and abundance of bean leaf beetles, Cerotoma trifurcata (Förster), were examined throughout two eastern South Dakota growing seasons in relation to grain yields in chisel- and ridge-tilled soybeans [Glycine max (L.) Merrill] grown in 2-yr rotation with corn (Zea mays L.) with and without added nitrogen (N). Populations were also sampled early and late season in alfalfa (Medicago sativa L.). Beetles were present in alfalfa by late May and most were reproductively active within a week, but their presence in alfalfa did not always precede soybean emergence. Most beetles taken from alfalfa in late fall were teneral; all were previtellogenic and unmated. Reproductively active beetles were detected in soybeans as soon as seedlings emerged. A partial second generation apparently occurred each year. First-generation beetles started to emerge in soybean fields during the first or third week of July but, whether emergence started early or late, most beetles emerging after July seemingly failed to mature their eggs and started leaving soybeans within several weeks of eclosion. This pattern suggested that any second generation arose from only the earliest emerging beetles of the first generation, with later emerging individuals having to overwinter before reproducing. Thus, any factors delaying emergence of the first generation, such as delayed soybean planting, could potentially limit its reproductive capacity through winter mortality. Cumulative seasonal beetle counts were lower in N-treated subplots and in ridge-tilled compared with chisel-tilled plots. Soybean grain yield increased with decreases in peak abundance of first-generation beetles and with N fertilization.
 
Number of eggs, nymphs, and adults of N. viridula per sample in early planted corn. (A) Least squares means for each sampling date in four Þelds in 2004 (SE ϭ 0.041 for eggs, 0.621 for nymphs, and 0.056 for adults). (B) Least squares means for each sampling date in two Þelds in 2005 (SE ϭ 0.02 for eggs, 0.57 for nymphs, and 0.04 for adults). (C) Means for each sampling date in Þeld in 2007. Error bars represent SEM. V, vegetative state; VT, Þnal vegetative stage; S, silking; E, maturing ears; ME, mature ears. 
Number of eggs, nymphs, and adults of E. servus per sample in early planted corn. (A) Least squares means for each sampling date in four Þelds in 2004 (SE ϭ 0.037 for eggs, 0.038 for nymphs, and 0.072 for adults). (B) Least squares means for each sampling date in two Þelds in 2005 (SE ϭ 0.019 for eggs, 0.031 for nymphs, and 0.081 for adults). (C) Means for each sampling date in Þeld in 2007. Error bars represent SEM. V, vegetative state; VT, Þnal vegetative stage; S, silking; E, maturing ears; ME, mature ears. 
Number of eggs, nymphs, and adults of N. viridula per sample in late-planted corn. (A) Least squares means for each sampling date in corn Þeld four in 2005 (SE ϭ 0.042 for eggs, 0.768 for nymphs, and 0.38 for adults). (B) Means for each sampling date in Þeld in 2009. Error bars represent SEM. V, vegetative state; VT, Þnal vegetative stage; S, silking; E, maturing ears; ME, mature ears. 
Number of eggs, nymphs, and adults of E. servus per sample in late-planted corn. (A) Least squares means for each sampling date in two Þelds in 2003 (SE ϭ 0.12 for eggs, 0.47 for nymphs, and 0.4 for adults). (B) Least squares means for each sampling date in corn Þeld four in 2005 (SE ϭ 0.048 for eggs, 0.246 for nymphs, and 0.334 for adults). V, vegetative state; VT, Þnal vegetative stage; S, silking; E, maturing ears; ME, mature ears. 
Number of eggs, nymphs, and adults of E. servus per sample in late-planted corn. (A) Least squares means for each sampling date in corn Þeld three in 2005 (SE ϭ 0.048 for eggs, 0.246 for nymphs, and 0.334 for adults). (B) Means for each sampling date in Þeld in 2009. Error bars represent SEM. V, vegetative state; VT, Þnal vegetative stage; S, silking; E, maturing ears; ME, mature ears. 
Article
The species composition and abundance of stink bugs (Heteroptera: Pentatomidae) in corn, Zea mays L., was determined in this on-farm study in Georgia. Seven species of phytophagous stink bugs were found on corn with the predominant species being Nezara viridula (L.) and Euschistus servus (Say). All developmental stages of these two pests were found, indicating they were developing on the corn crop. The remaining five species, Oebalus pugnax pugnax (F.), Euschistus quadrator (Rolston), Euschistus tristigmus (Say), Euschistus ictericus (L.), and Acrosternum hilare (Say), were found in relatively low numbers. Adult N. viridula were parasitized by the tachinid parasitoid Trichopoda pennipes (F.). There was a pronounced edge effect in distribution of stink bugs in corn. Population dynamics of N. viridula and E. servus were different on early and late-planted corn. Oviposition by females of both stink bug species occurred in mid-to-late-May and again mid-to-late-June in corn, regardless of planting date. In early planted fields, if stink bug females oviposited on corn in mid-July, the resulting nymphs did not survive to the adult stage in corn because ears were close to physiological maturity and leaves were senescing. Density of stink bug adults in early planted corn was relatively low throughout the growing season. In late-planted corn, females of both stink bug species consistently laid eggs in mid-to-late-July on corn with developing ears. This habitat favored continued nymph development, and the resulting adult population reached high levels. These results indicate that corn management practices play a key role in the ecology of stink bugs in corn agroecosystems and provide information for designing management strategies to suppress stink bugs in farmscapes with corn.
 
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