Showing papers on "Infestation published in 2005"

Attraction of the Parasitoid Anagrus nilaparvatae to Rice Volatiles Induced by the Rice Brown Planthopper Nilaparvata lugens

Abstract: Anagrus nilaparvatae, an egg parasitoid of the rice brown planthopper Nilaparvata lugens, was attracted to volatiles released from N. lugens-infested plants, whereas there was no attraction to volatiles from undamaged plants, artificially damaged plants, or volatiles from N. lugens nymphs, female adults, eggs, honeydew, and exuvia. There was no difference in attractiveness between plants infested by N. lugens nymphs or those infested by gravid females. Attraction was correlated with time after infestation and host density; attraction was only evident between 6 and 24 hr after infestation by 10 adult females per plant, but not before or after. Similarly, after 24 hr of infestation, wasps were attracted to plants with 10 to 20 female planthoppers, but not to plants with lower or higher numbers of female planthoppers. The attractive time periods and densities may be correlated with the survival chances of the wasps' offspring, which do not survive if the plants die before the wasps emerge. Wasps were also attracted to undamaged mature leaves of a rice plant when one of the other mature leaves had been infested by 10 N. lugens for 1 d, implying that the volatile cues involved in host location by the parasitoid are systemically released. Collection and analyses of volatiles revealed that 1 d of N. lugens infestation did not result in the emission of new compounds or an increase in the total amount of volatiles, but rather the proportions among the compounds in the blend were altered. The total amounts and proportions of the chemicals were also affected by infestation duration. These changes in volatile profiles might provide the wasps with specific information on host habitat quality and thus could explain the observed behavioral responses of the parasitoid.

Aphid Infestation Causes Different Changes in Carbon and Nitrogen Allocation in Alfalfa Stems as Well as Different Inhibitions of Longitudinal and Radial Expansion

Abstract: Alfalfa (Medicago sativa) stem elongation is strongly reduced by a pea aphid (Acyrthosiphon pisum Harris) infestation. As pea aphid is a phloem feeder that does not transmit virus or toxins, assimilate withdrawal is generally considered as the main mechanism responsible for growth reduction. Using a kinematic analysis, we investigated the spatial distributions of relative elemental growth rates of control and infested alfalfa stems. The water, carbon, and nitrogen contents per unit stem length were measured along the growth zone. Deposition rates and growth-sustaining fluxes were estimated from these patterns. Severe short-term aphid infestation (200 young adults over a 24-h period) induced a strong and synchronized reduction in rates of elongation and of water and carbon deposition. Reduced nitrogen content and associated negative nitrogen deposition rates were observed in some parts of the infested stems, especially in the apex. This suggested a mobilization of nitrogen from the apical part of the growth zone, converted from a sink tissue into a source tissue by aphids. Calculation of radial growth rates suggested that aphid infestation led to a smaller reduction in radial expansion than in elongation. Together with earlier observations of long-lasting effects of a short-term infestation, this supports the hypothesis that in addition to nutrient withdrawal, a thigmomorphogenesis-like mechanism is involved in the effect of aphid infestation on stem growth.

Current Status of Red Palm Weevil Infestation in Date Palm Plantations in Israel

Abstract: The red palm weevilRhynchophorus ferrugineus (Olivier) (RPW) is the most serious pest of date palms in the Middle East. Weevil infestation was first detected in Israel in the summer of 1999 in date plantations in the Jordan Valley, on the west bank of the Jordan River and in the northern area of the Dead Sea. For 2 years following the discovery of the pest, prophylactic insecticide chemical treatments as well as adult weevil trapping were carried out over 450 ha of date palm plantations. Traps loaded with a commercial aggregation pheromone, ferrugineol, supplemented with ethyl acetate and a fermenting mixture of dates and sugarcane molasses, were posted in high trap density (approx. ten traps per ha) in order to monitor weevil infestation and reduce the RPW population by mass trapping. A significant decrease in number of trapped beetles and infested trees was observed in 2001 and continued in the following years. No infested trees have been found since 2002, indicating a decrease in RPW population. The sex ratio of trapped adults during 3 years of study was significantly female-biased (∼2.5:1). Therefore, mass trapping might have played a significant role in the suppression of RPW populations in date plantations.

Field ecology of sylvatic Rhodnius populations (Heteroptera, Triatominae): risk factors for palm tree infestation in western Ecuador.

Abstract: Most Rhodnius species (Triatominae) are primarily associated with palm trees. They maintain enzootic Trypanosoma cruzi transmission and are responsible for human infection (causing Chagas disease) through the Neotropics. Assessing whether individual palm traits (ecological and/or botanical) may increase the risk of palm infestation by triatomines is relevant in areas where bugs invade houses flying from peridomestic palms. We developed a novel fieldwork approach with that objective, and applied it to study infestation by sylvatic Rhodnius ecuadoriensis in 110 tagua palms (Phytelephas aequatorialis). Palm infestation (23% overall) was non-randomly distributed in our sample. Palms located in anthropic landscapes were frequently infested (>27%, n=92), whereas no bugs were collected from palms surveyed within forest remnants (n=18; P=0.01). The presence of abundant decaying vegetable matter (P=0.001) and (to a lesser extent) epiphytic plants (P=0.049) on palm crowns and stems increased the probability of infestation and was positively correlated with the apparent density of bug colonies (R2=0.68). A trend towards higher infestation rates in male palms (34% vs. 18%) could relate to female palm management (removal of infrutescences and vegetable debris) in areas where palm seeds are harvested. An outline of 'risk palm ecotopes' and environmental management-based strategies for the control of peridomestic, palm tree-living vector populations are proposed.

Hosts and Pathogen Detection for Immature Stages of Ixodes ricinus (Acari: Ixodidae) in North-Central Spain

Abstract: To determine hosts of the immature stages of a southern population of Ixodes ricinus, we trapped rodents and birds in an area of north-central Spain in May–June and August–September of 1998 and 1999. The most frequently trapped rodents were Apodemus sylvaticus (230 specimens) and Clethrionomys glareolus (99), with a larval infestation prevalence of 49% and 81%, respectively (in spring) and 21% and 41% (in summer). C. glareolus was always more heavily parasitized by larvae (mean numbers 19.8 in spring, 3.4 in summer) than A. sylvaticus (6.1 and 1.2, respectively). No nymphs were collected from the rodents. The larval distribution pattern differed considerably between rodent host species but not according to the season of the year. The most commonly trapped birds were members of the Turdidae, which had infestation incidences of about 70% (larvae) and 10% (nymphs) in spring and 20–15% in summer. We also used molecular methods for the identification of reservoir hosts of the larval ticks and of the pathogens they contained, from nymphs collected in the same site in June of 2002 and 2003. The study showed that most of the ticks had fed on birds and few on rodents and ruminants. Pathogens detected in these ticks included Babesia microti, Borrelia garinii, B. valaisiana and B. afzelii. Borrelia afzelii was detected in a tick that had apparently fed on a wild boar.

Prevalence of pediculosis capitis and determination of risk factors in primary-school children in Kerman.

Abstract: This descriptive, analytical study was carried out in 2003 to determine the prevalence of pediculosis capitis and some risk factors among primary-school pupils in Kerman. We selected 1200 pupils (53% girls) from 50 primary schools by multistage, systematic random sampling. Their hair was examined for head louse infestation: 45 (3.8%) were infected with lice, 43 (95.5%) girls and 2 (4.5%) boys. The highest rate of infestation was in 9-year-olds. There was a significant relationship between head louse infestation and sex (P < 0.0001), age (P < 0.05), parents' education (P < 0.0001), father's job (P < 0.01), family size (P < 0.01), length of hair (P < 0.0001) and having separate bathing facilities in the house (P < 0.0001).

Worm infestation and the negative association with eczema (atopic/nonatopic) and allergic sensitization

Abstract: Background: Worm infestations may play a role in preventing allergies. There is a lack of epidemiological information from Western countries on the association between worm infestation and eczema. Objective: To investigate the association between worm infestation and eczema in a proper temporal sequence and under consideration of allergic sensitization. Methods: Two surveys were performed in East German school children. Questionnaire data included the history of eczema and worm infestation and their time of onset. Specific IgE antibodies to five common aeroallergens were measured and used to define nonatopic and atopic eczema. Logistic regression analyses were performed to control for relevant confounders (age, sex, parental school education and history of allergies). In order to confirm the findings a corresponding conditional regression analysis was applied on cases and controls matched by age and sex. Results: A total of 4169 children participated (response 75 and 76%) who were, on average, 9.2 years old (47% girls). Overall 17.0% reported a prior worm infestation (Ascaris 44%, Oxyuris 33%) and 18.1% had a history of eczema. Eczema occurred significantly less frequent in children who had a worm infestation (prior to the onset of eczema) compared with children without such a history (8.1%vs 16.5%, ORadj: 0.45, 95% CI: 0.33–0.60). The finding was confirmed by the corresponding matched case–control analysis (ORadj: 0.57, 95% CI: 0.41–0.79). Atopic eczema was affected more by a prior worm infestation (ORadj: 0.31, 95% CI: 0.18–0.56) than the nonatopic eczema (ORadj: 0.58, 95% CI: 0.40–0.84). A total of 29.1% exhibited specific IgE antibodies to at least one aeroallergen. Sensitized children gave significantly less frequent a history of worm infestation (14.2%vs 18.3%, ORadj: 0.74, 95% CI: 0.60–0.92). Stratified analysis revealed that this effect most pronounced for a sensitization to house dust mite. Conclusions: A worm infestation is associated with a reduced frequency of subsequent eczema, especially the atopic type. Furthermore allergic sensitization, especially to house dust mite, and worm infestation are negatively associated. The data support the concept that a lack of immune-stimulation by parasitic infections contributes to the development of allergies.

Effect of a turnip rape (Brassica rapa) trap crop on stem-mining pests and their parasitoids in winter oilseed rape (Brassica napus)

Abstract: Concerns about the negative effects of chemical control of oilseed rape (Brassica napus L.) pests on non-target species, human safety, and development of insecticide resistance, require alternative control strategies such as the use of trap crops and biocontrol to be developed. Psylliodes chrysocephala(L.) (Coleoptera: Chrysomelidae) (cabbage stem flea beetle) and Ceutorhynchus pallidactylus (Marsh.) (Coleoptera: Curculionidae) (cabbage stem weevil) are two major stem-mining pests of oilseed rape. This study investigated the phenology of these pests and their main parasitoids in the UK, the potential use of turnip rape (Brassica rapa L.) as a trap crop to reduce oilseed rape infestation, and the effects of insecticide treatment on pest incidence and larval parasitism. Water trap samples, plant dissections and pest larval dissections were done to determine: the incidence of adult pests and their parasitoids, the level of plant infestation by the pests and percentage larval parasitism, respectively. The turnip rape trap crop borders reduced P. chrysocephalabut not C. pallidactylus infestation of oilseed rape plots. Treatment of the trap crop with insecticide had little effect on either pest or parasitoid incidence in the oilseed rape. TersilochusmicrogasterSzep. andT. obscurator Aub. (Hymenoptera: Ichneumonidae) were the main larval parasitoids of P. chrysocephalaand C. pallidactylus, respectively. Tersilochus microgasteris reported for the first time in the UK. The implications for integrated pest management are discussed.

Protection of fruit against infestation by apple maggot and blueberry maggot (Diptera: Tephritidae) using compounds containing spinosad.

Abstract: Two insecticide formulations containing the naturalyte insecticide spinosad, GF-120 Fruit Fly Bait and SpinTor 2 SC, were compared for control of apple maggot, Rhagoletis pomonella (Walsh), and blueberry maggot, Rhagoletis mendax Curran. In 2002 and 2003, larval infestation in blueberries and apples was significantly lower in plots treated with GF-120 (spinosad bait) or SpinTor than in untreated control plots. Fruit fly infestation in apples was reduced by 67% in 2002 after weekly application of GF-120 for 6 wk. Six weeks of GF-120 treatment reduced infestation in blueberries by 85% in 2002 and 98% in 2003. Plots treated weekly with the bait component of GF-120 for 6 wk had significantly higher infestation of blueberry maggot larvae compared with untreated plots in 2002. Observations of wild R. mendax flies revealed that similar numbers of flies landed on blueberry foliage treated with spinosad bait, the bait component alone, or water droplets. However, flies on spinosad bait and bait treated plants spent significantly more time within 5 cm of the treatment droplets compared with control (water) droplets. Overall, the results demonstrate a high degree of efficacy of baited spinosad formulations against these key pests of temperate fruit and suggest that GF-120 is an arrestant for foraging flies.

Pediculus capitis infestation according to sex and social factors in Argentina Infestação por Pediculus capitis segundo sexo e fatores sociais na Argentina

Abstract: Objective To determine the intensity of Pediculus capitis infestation (abundance) among Argentinean schoolchildren. Children’s sex and social stratum were analyzed as modifiers of the general prevalence and degree of parasitism. Methods The study included 1,370 schoolchildren (692 girls, 678 boys) from 26 schools of the province of La Rioja (21 public schools, five private schools). Classic prevalence was obtained as the percentage of children with nits and/or lice. Moreover, five degrees of parasitism were classified: 0) children with no signs of pediculosis; 0+) children with evidence of past infestation; 1) children with a recent infestation and low probability of active parasitism; 2) children with a recent infestation and high probability of active parasitism; 3) children with mobile lice (active pediculosis). Results The general prevalence was 61.4% (girls: 79%; boys: 44%, p<0.001). Private schools showed lower prevalence than public schools (p=0.02), especially due to the low prevalence in boys. Fifty percent of children were classified in classes 0 and 0+, 22% in class 1; and 28% in grades 2 and 3. The proportion of children in grade 3 was higher in public schools than in private schools. There were significant sexual differences in the intensity of parasitism for grades 2 and 3, where girls’ rates exceeded twice those of boys’. Conclusions Sex and social stratum are important modifiers of P. capitis general prevalence and degree of infestation. The classification of children by intensity of infestation allowed a more precise delimitation of this condition, which is especially important for disease surveillance and application of control measures.

Influence of physico-chemical traits of bitter gourd, Momordica charantia L. on larval density and resistance to melon fruit fly, Bactrocera cucurbitae (Coquillett)

Abstract: Melon fruit fly, Bactrocera cucurbitae (Coquillett) is one of the most important pests of bitter gourd, Momordica charantia L. Because of the difficulties associated with chemical control of this pest, it is important to identify the traits associated with resistance and their influence on pest multiplication. There were significant differences in test genotypes for fruit infestation and larval density/fruit. The wild accessions, IC 256185, IC 248256, IC 213311, IC 248282, IC 256110 and IC 248281 were identified as resistance sources to melon fruit fly. There was a significant and positive correlation ( r = 0.96) between percentage fruit infestation and larval density/fruit. Percentage fruit infestation and larval density/fruit were positively correlated with depth of ribs, flesh thickness, fruit diameter and fruit length, and negatively associated with fruit toughness. Flesh thickness and fruit diameter explained 93.0% of the total variation for fruit fly infestation, and flesh thickness and fruit length explained 76.3% of the variation for larval density/fruit. Ascorbic acid, nitrogen, phosphorus, potassium, protein, reducing sugars, non-reducing sugars and total sugars were negatively correlated, while the moisture content showed a positive association with fruit fly infestation and larval density/fruit. Moisture, potassium and reducing sugar content explained 97.4% of the total variation in fruit infestation, while moisture, phosphorus, protein, reducing and total sugars explained 85.7% variation for larval density/fruit

Influence of Summer Stream Temperatures on Black Spot Infestation of Juvenile Coho Salmon in the Oregon Coast Range

Abstract: High summer water temperatures can adversely affect stream salmonids in numerous ways. The direct effects of temperature associated with increased metabolic demand can be exacerbated by other factors, including decreased resistance to disease and increased susceptibility to parasites. We quantified the occurrence of black spot infestation caused by a neascus-type trematode (family Diplostomidae) of juvenile salmonids in Oregon's West Fork Smith River stream network during summer 2002 through fall 2003. The highest 7-d average of the daily maximum (ADM) temperatures was positively correlated with infestation rates in both years. We summarized the frequency and infestation severity of juvenile coho salmon Oncorhynchus kisutch by location within the network and summarized temperatures for 19 study reaches. Summer ADMs ranged from approximately 24°C near the watershed mouth to approximately 17°C in the upper reaches, while tributary ADMs ranged from approximately 16–18°C in the lower reaches to 12–17...

Infestation of Aedes aegypti estimated by oviposition traps in Brazil Infestação por Aedes aegypti estimada por armadilha de oviposição em Salvador, Bahia

Abstract: Objective To assess infestation levels of Aedes aegypti using the oviposition trap (ovitrap) method and to compare these results with data obtained with the use of indices traditionally applied in public programs aimed at fighting this vector. Methods Nine sentinel areas in Northeastern, Brazil, were assessed and infestation levels were measured for a nine-month period. Egg density and container indices were estimated and compared with previous results found using the house index and Breteau index. Results The results indicated that the area studied was infested with this vector during the entire study period and that the infestation was widespread in all areas. Different results were found with the different indices studied. There were areas in which the house index and the Breteau index were negative or close to zero, whereas the container index for the same area was 11% and the egg density index was 8.3%. Conclusions The container and egg density indices allow better assessment of infestation rates in a city than the conventionally used indices (house index and Breteau index). At lower operational costs and easier standardization, these indices can be applied as a measurement tool for assessing infestation rates during entomological surveillance in programs to fight Aedes aegypti.

Moscas ectoparasitas (Diptera, Streblidae) de morcegos (Chiroptera, Phyllostomidae) no sul do Brasil: associações hospedeiros-parasitos e taxas de infestação

Abstract: Hosts-parasites associations, including infestation rates, between ectoparasitic bat flies of the family Streblidae and bats of the family Phyllostomidae were studied in Atlantic Forest habitats in southern Brazil For the more abundant phyllostomid bats, the prevalence and mean intensity of fly infestation were determined during the different seasons of the year and in relation to the sex and age of their hosts From four species of bats (Anoura caudifera (E Geoffroy, 1818), Artibeus fimbriatus Gray, 1838, Artibeus lituratus (Olfers, 1818) and Sturnira lilium E Geoffroy, 1810), were collected 118 specimens of bat flies belonging to seven species (Anastrebla caudiferae Wenzel, 1976, Megistopoda aranea (Coquillett, 1899), Megistopoda proxima (Seguy, 1926), Metelasmus pseudopterus Coquillett, 1907, Paratrichobius longicrus (Miranda Ribeiro, 1907), Trichobius phyllostomae Kessel, 1925 and Trichobius tiptoni Wenzel, 1976) Low infestation rates were found in A lituratus, A fimbriatus and S lilium and there were a tendency for the bats to be more parasited in summer and autumn, probably related to the seasonal temperatures in the region studied because such temperatures affect the reproductive and mortality rates of the ectoparasites For A lituratus, the age or sex of the host did not affect the infestation rates by P longicrus Although the age or sex of S lilium did not, in general, affect the rate of infestation by M proxima, juvenile S lilium appeared to be more frequently parasitized by M proxima than did adult bats The data indicate that there are no behavioral differences linked to the age and sex of the species of phyllostomid bats studied which favor or disfavor infestation by Streblidae

Effect of Three Plant Residues and Chicken Manure used as Biofumigants at Three Temperatures on Meloidogyne incognita Infestation of Tomato in Greenhouse Experiments.

Abstract: Plant residues of broccoli, melon, and tomato with or without addition of chicken manure were used as biofumigants in two pot experiments with Meloidogyne incognita-infested soils. The efficacy of these biofumigants in controlling M. incognita infestation in susceptible tomato bio-assay plants was studied at soil temperatures of 20 masculine, 25 masculine, and 30 masculineC. None of the plant residues was effective at 20 masculineC, and broccoli was more effective than tomato or melon at 25 masculineC. At 30 masculineC all three plant residues reduced M. incognita infestation of tomato to very low levels. Chicken manure was effective in one of two experiments at 20 masculineC, and at 25 masculineC enhanced the efficacy of tomato and melon residue in one of two experiments. At 30 masculineC chicken manure was equally effective as the three plant residues but did not further decrease infestation levels in plant residue amended soils. It is concluded that biofumigation to control M. incognita is unlikely to be effective under cool conditions, that at soil temperatures around 25 masculineC broccoli is more effective than melon and tomato, and that the addition of chicken manure at this soil temperature may enhance the efficacy. At high soil temperatures, of approximately 30 masculineC, the biofumigant source seems of minor importance as strong reductions in tomato infestation by M. incognita were achieved by addition of each of the three plant residues as well as by addition of chicken manure.

Infestation of Aedes aegypti estimated by oviposition traps in Brazil

Abstract: OBJECTIVE: To assess infestation levels of Aedes aegypti using the oviposition trap (ovitrap) method and to compare these results with data obtained with the use of indices traditionally applied in public programs aimed at fighting this vector. METHODS: Nine sentinel areas in Northeastern, Brazil, were assessed and infestation levels were measured for a nine-month period. Egg density and container indices were estimated and compared with previous results found using the house index and Breteau index. RESULTS: The results indicated that the area studied was infested with this vector during the entire study period and that the infestation was widespread in all areas. Different results were found with the different indices studied. There were areas in which the house index and the Breteau index were negative or close to zero, whereas the container index for the same area was 11% and the egg density index was 8.3%. CONCLUSIONS: The container and egg density indices allow better assessment of infestation rates in a city than the conventionally used indices (house index and Breteau index). At lower operational costs and easier standardization, these indices can be applied as a measurement tool for assessing infestation rates during entomological surveillance in programs to fight Aedes aegypti.

Effect of soil-applied complex fertiliser on an insect–host plant relationship: Liriomyza trifolii on Solanum tuberosum

Abstract: Insects respond to very low levels of nutritional and non-nutritional compounds in plants, which influence their acceptance and colonisation of the plant or plant part, and thereby their growth and development. Plant nutrient levels can vary within and between plants, and are influenced by external factors such as fertiliser treatments, irrigation regime, and light. Soil levels of nitrogen, potassium, phosphorus, calcium, and magnesium can have significant effects on the amounts of these nutrients in the plant, and thereby on pest infestation. This study reports on the influence of seven different NPK fertiliser rates in potted potato (Solanum tuberosum cv. Mondial) plants on the nitrogen, phosphorus, potassium, calcium, and magnesium levels in the leaves, and the concomitant influence on infestation by, and development of, the serpentine leafminer, Liriomyza trifolii Burgess (Diptera: Agromyzidae). Results showed that increases in nitrogen in the potato leaves increased larval and pupal survival, and pupal and adult body weight and length. Potassium and phosphorus, on the other hand, decreased the host suitability of potato plants to L. trifolii, and were detrimental to the pest.

A prescription for longer life? bot fly parasitism of the white-footed mouse

Abstract: Investigation of host-parasite interactions typically reveals a negative impact of parasitism on the host species In contrast, mounting evidence indicates that bot fly (Cuterebra sp) infestation enhances the survival of white-footed mice ( Peromyscus leu- copus) We propose that life history trade-offs, namely, between reproduction and survival, can explain this counterintuitive observation By using an extensive data set spanning a decade, 12 sites in two states, and over 30 000 mouse captures, we offer a new perspective on the effects of bot fly parasitism on white-footed mice Analysis of persistence time corroborated earlier studies that showed significantly higher survival rates of infested mice Although a higher proportion of infested than uninfested females were in breeding condition, secondary reproductive success appeared to be negatively impacted by parasitism via de- clines in the number of litters and the total number of offspring produced by infested females Population growth rates were negatively correlated with infestation prevalence, further indicating a negative effect of parasitism Based on the negative impact of parasitism on reproduction, we propose that enhanced survival of infested mice can be explained by the diversion of resources from reproduction to body maintenance Parasite-induced life history shifts in which mice decrease current reproduction to promote future reproduction, such as increasing the age at maturity, may also contribute to the decline in population growth rate observed in years of high infestation prevalence

Frequency of Intestinal Parasite Infestation in Children Hospital Quetta

Abstract: Objectives: To determine the frequency and pattern of intestinal infestation among children. Patients and Methods: Fecal samples were tested in 220 patients presenting with recurrent abdominal discomfort. The patients belonged mainly to Quetta. The gross examinations of the stools were made for presence of worms and segments. The microscopic examination of the stool was made by direct wet smears in normal saline and Lugol’s iodine. Results: Overall infestation rate was 31%. The most common parasite was Hymenolepis nana (34%) followed by Giardia lamblia (32%). Entamoeba histolytica (29%), Ascaris lumbricoides (4%) Ankylostoma duodenale (1%). Conclusions: Intestinal infestation is common among children in Quetta and might be one of the reasons of anemia and malabsorption in this group.

Within-field spatial distribution of Cephus cinctus (Hymenoptera: Cephidae) larvae in Montana wheat fields

Abstract: 214 Abstract—The wheat stem sawfly, Cephus cinctus Norton, is a major insect pest in dryland wheat (Triticum L. spp.; Poaceae) fields in the northern Great Plains of the United States and in southern regions of the prairie provinces of Canada. Field infestations by this pest commonly show a distinct "edge effect", with infestation levels highest at the field edge and declining in- wards. In this study, we characterized the edge effect of C. cinctus infested wheat fields in Montana at four locations in two separate years. "Infestation level" refers to the average propor- tion of wheat stems infested with C. cinctus in samples collected in a given wheat field. The gradual decrease in C. cinctus infestation towards the centre of wheat fields is referred to as the "infestation slope", and it was presented as a proportion of infestation level at field edges. We showed that (i) for most of the fields bordering grassland or fallow wheat, a simple exponential decline curve provided a significant fit to the infestation slope; (ii) the infestation slopes in dif- ferent fields and in different directions within fields were similar and appeared to be independent of the overall infestation level; and (iii) the relationship between infestation level and the propor- tion of samples infested followed an asymptotic curve, which indicates a high level of dispersal of ovipositing C. cinctus females. The general perception has been that the edge effect of C. cinctus infestation is a result of ovipositing C. cinctus females being both weak flyers and short-lived, but our results do not fully corroborate this perception. Currently, the only reliable way to detect C. cinctus infestations is to dissect individual stems and look for developing in- stars. However, this type of sampling is extremely time consuming and labor intensive and there- fore impractical for wheat growers. Increasing the understanding of the spatial patterns in C. cinctus infestations is a first step towards development of an optimal sampling plan for this important field pest. Thus, the results presented are relevant for researchers involved in sampling designs and integrated pest management procedures for field pests. We discuss behavioral and evolutionary factors that may contribute to the edge effect of C. cinctus infestations.

Reproductive phenology and pre‐dispersal seed‐feeding in Protium tovarense (Burseraceae), with a description of the first known phytophagous “Bracon” species (Hymenoptera: Braconidae: Braconinae)

Abstract: The reproductive phenology of the cloud forest tree Protium tovarense (Burseraceae) is analysed for one population in northern Venezuela. Reproductive phenophases were monitored using both long‐term(21 years) and detailed short‐term (4 years) surveys of flower and fruit set. The reproductive phenology of this tree varies, with periods in which the species behaves as a supra‐annual reproducer, and other periods in which it reproduces annually, at the end of the rainy season. Marked spatial variation in reproductive condition was also observed, with subpopulations separated by less than 2 km showing contrasting phenological stages. Larval infestation of seeds by a braconid wasp was observed for a period of 1 year and is described. This wasp, the first obligately phytophagous species of Braconinae, is described as Bracon phytophagus Quicke sp. n. Percentage fruit infestation by this wasp was relatively high (50–60%) during the entire period (∼10 months) of fruit development. The larval stages are described a...

Infestation by Enneothrips flavens Moulton and yield of peanut cultivars

Abstract: Because of damages caused, general occurrence in crops, and high population levels, the most important peanut pest in Brazil is the thrips Enneothrips flavens Moulton (Thysanoptera: Thripidae). A field experiment was carried out during the 2001/2002 growing season, in Campinas and Pindorama, State of Sao Paulo, Brazil, to evaluate the influence of E. flavens on yield of six peanut cultivars. Treatments comprised three cultivars of the upright type and three of the runner type, with and without chemical control of the insect. Thrips infestation was evaluated by insect countings on young leaflets. Yield and yield reduction percentage due to the lack of thrips control were estimated. The lack of insect control resulted in yield reductions varying from 19.5 to 62.7%, depending on the level of infestation, cultivars, and location. Runner cultivar IAC Caiapo, presented the lowest yield reductions in both locations (19.5 and 28.7%), even when exposed to thrips infestation for a longer period because of its longer cycle. This fact characterizes 'IAC Caiapo' as resistant to E. flavens.

Suscetibilidade da soja a percevejos na fase anterior ao desenvolvimento das vagens

Abstract: The objective of this work was to evaluate the damages caused by stink bug populations of Euschistus heros (F.) and Piezodorus guildinii (West.) to soybean crop on november/december, prior to pod set. Greenhouse and field experiments were carried out comparing infestations at vegetative-flowering and pod development stages. Soybean plants at vegetative and flowering growth stages, even under severe bugs infestation (8 per plant) did not show significant yield reduction. Seed quality, was similar among population levels and bug species. At R4 stage, the number of seedless pods increased proportionally to the number of bugs per plant. In field experiment, yield and seed quality of soybean plants infested with up to four E. heros or P. guildinii adults per meter, at the end of the vegetative-flowering stage, were similar to bug-free plants. The number of bug- punctured and inviable seeds increased and the average yield decreased with the increase of population levels of both bug species, at the pod filling stage (R5-R6) infestation. In relation to the soybean quality, the damage caused by P. guildinii was twice bigger than that caused by the brown stink bug. Infestations of these stink bugs on the vegetative-flowering stage do not cause reduction on yield and quality of soybean seeds.

Influence of agro-environmental factors on fusarium infestation and population structure in wheat kernels.

Abstract: The influence of location, year and cultivar on occurrence, level of infestation and Fusarium species spectrum in winter wheat seeds were evaluated. The wheat seeds from different cultivars and localities of the Slovak Republic were used for Fusarium species evaluation during years 1999, 2000, 2002 and 2003. The significant influence of the locality on total Fusarium kernel infestation was confirmed. The total sample infestation was significantly higher in the colder and moister localities, lower infestation was in warmer and dryer ones. Cultivar "Astella" was significantly the most susceptible. The widest Fusarium species spectrum was recorded in the locations with a high level of total kernel infestation. In localities with lower infestation, the species spectrum was less numerous. F. poae was the dominant species in all locations. The species F. culmorum, F. avenaceum and Microdochium nivale were subdominant and relatively frequent in the locations with higher altitude. The frequency and density of other isolated species ( F. graminearum, F. sporotrichioides, F. tricinctum, F. semitectum, F. acuminatum, F. heterosporum, F. sambucinum, F. solani, F. compactum and F. oxysporum) was trivial in all localities. The kernel infestation and Fusarium population structure in wheat grains mostly depends on microclimatic condition of the locality. Rising of rainfall rate and altitude led to an increase in the species spectrum. The wide Fusarium species spectrum is connected with the high frequency of coincident species. The species with low and medium frequency achieved low or trivial density in population structure.