Low Infestation Rates Research Articles

The impact of an invasive ambrosia beetle on the riparian habitats of the Tijuana River Valley, California.

The Tijuana River Valley is the first natural habitat in California to be substantially invaded by the Kuroshio Shot Hole Borer (KSHB, Euwallacea sp.), an ambrosia beetle native to Southeast Asia. This paper documents the distribution of the KSHB in the riparian vegetation in the valley and assesses the damage done to the vegetation as of early 2016, approximately six months after the beetle was first observed in the valley. I divided the riparian habitats into 29 survey units so that the vegetation within each unit was relatively homogenous in terms of plant species composition, age and density. From a random point within each unit, I examined approximately 60 individuals of the dominant plant species for evidence of KSHB infestation and evidence of major damage such as limb breakage. In the 22 forested units,I examined the dominant arroyo and black willows (Salix lasiolepis Benth. and S. gooddingii C.R. Ball), and in the seven scrub units, I examined mule fat (Baccharis salicifolia (Ruiz & Pav.) Pers.). Evidence of KSHB infestation was found in 25 of the 29 units. In the forest units, infestation rates ranged from 0 to 100% and were high (>60%) in 16 of the units. In the scrub units, infestation rates ranged from 0 to 33%. Infestation rates were significantly correlated with the wetness of a unit; wetter units had higher infestation rates. Evidence of major physical damage was found in 24 units, and dense stands of willows were reduced to broken trunks in several areas. Overall, I estimated that more than 280,000 (70%) of the willows in the valley were infested, and more than 140,000 had suffered major limb damage. In addition, I recorded evidence of KSHB infestation in the other common plant species in the valley; of the 23 species examined, 14 showed evidence of beetle attack. The four species with the highest rates of infestation were native trees in the Salicaceae family. The three species considered to be the worst invasive plants in the valley, Ricinus communis L., Tamarix ramosissima Ledeb. and Arundo donax L., had low rates of infestation. Several findings from this study have significance for resource managers: (1) the KSHB attack caused extensive mortality of trees soon after being first discovered so, if managers are to control the spread of the beetle, they will need to develop an effective early detection and rapid response program; (2) infestation rates were highest in units that were wet, so resource managers trying to detect the beetle in other areas should thoroughly search trees near water, particularly nutrient-enriched water; (3) the infestation appears to be a novel form of disturbance, and the affected forests may need special management actions in order to recover; and (4) the infestation has altered the structure of the forest canopy, and this is likely to promote the growth of invasive plant species that were relatively inconspicuous in the forests prior to the beetle attack but will now need more attention.

Vertical Distribution of Termites on Trees in Two Forest Landscapes in Taiwan.

Termites are a key functional group in the forest ecosystem, but they damage trees. To investigate the termite infestation pattern on the whole tree, we cut 108 blackboard trees, Alstonia scholaris (L.) R. Br., and 50 Japanese cedars, Cryptomeria japonica (L. f.) D. Don, into sections. The bark surface and cross sections of the tree trunk were examined along the axes. A high percentage of blackboard trees (92.6%) was infested by fungus-growing termites, Odontotermes formosanus (Shiraki), but damage was limited to the bark surface at a 2-m height. The infestation rate of dampwood termites, Neotermes koshunensis (Shiraki), was only 4.6% (5/108), and all infestations were associated with trunk wounds. N. koshunensis was found at significantly higher portion of a tree than O. formosanus. Among 50 Japanese cedars, 20 living trees were not infested by any termites, but 26 of the 30 dead trees were infested by subterranean termites, Reticulitermes flaviceps (Oshima), which excavated tunnels in the trunk. The infestation rate at basal sections was higher than that at distal sections. Only one Japanese cedar tree was infested by another dampwood termite, Glyptotermes satsumensis (Matsumura). The two dominant termite species, O. formosanus and R. flaviceps, had subterranean nests and infested trees from bottom up. The two primitive termites N. koshunensis and G. satsumensis had low infestation rates and are most likely to infest trees by alates from top down. The niche segregation in trees of three termite families, Kalotermitidae, Rhinotermitidae, and Termitidae, was distinct.

Honey Bee Colonies Headed by Hyperpolyandrous Queens Have Improved Brood Rearing Efficiency and Lower Infestation Rates of Parasitic Varroa Mites.

A honey bee queen mates on wing with an average of 12 males and stores their sperm to produce progeny of mixed paternity. The degree of a queen’s polyandry is positively associated with measures of her colony’s fitness, and observed distributions of mating number are evolutionary optima balancing risks of mating flights against benefits to the colony. Effective mating numbers as high as 40 have been documented, begging the question of the upper bounds of this behavior that can be expected to confer colony benefit. In this study we used instrumental insemination to create three classes of queens with exaggerated range of polyandry– 15, 30, or 60 drones. Colonies headed by queens inseminated with 30 or 60 drones produced more brood per bee and had a lower proportion of samples positive for Varroa destructor mites than colonies whose queens were inseminated with 15 drones, suggesting benefits of polyandry at rates higher than those normally obtaining in nature. Our results are consistent with two hypotheses that posit conditions that reward such high expressions of polyandry: (1) a queen may mate with many males in order to promote beneficial non-additive genetic interactions among subfamilies, and (2) a queen may mate with many males in order to capture a large number of rare alleles that regulate resistance to pathogens and parasites in a breeding population. Our results are unique for identifying the highest levels of polyandry yet detected that confer colony-level benefit and for showing a benefit of polyandry in particular toward the parasitic mite V. destructor.

Local and Regional Variation in Local Frequency of Multiple Coffee Pests Across a Mosaic Landscape in Coffea arabica's Native Range

AbstractShaded coffee has been highlighted for its potential to conserve biodiversity, and thus perhaps also a diversity of natural enemies that could control pest organisms. In southwestern Ethiopia, coffee is grown in shade both in contiguous forests and in forest patches with native trees surrounded by open fields. We hypothesized that coffee grown in contiguous forests, which is the natural habitat for coffee (Coffea arabica) and its interacting organisms, would have less pest damage due to high protection by natural enemies. We surveyed pests on coffee plants in plots within contiguous forests (10 sites) and in forest patches (21 sites). In general, the variation in number of damaged or attacked leaves by individual insect or fungal pests was larger between plants than between plots, which suggests that very local conditions or processes are important. The spatial signals were generally weak. Coffee rust and coffee blotch miner tended to have lower infestation rates in accordance with our hypothesis, while fruit flies in ripe berries were more abundant in forest patches closer to contiguous forest. Based on interviews, olive baboons showed a clear dependency on contiguous forest habitat and were regarded as a problem only in contiguous forests and forest patches close to contiguous forests. In conclusion, we found no support for a generally stronger top‐down control on coffee pests in sites within, or with connectivity to, contiguous moist afromontane forests in the native range of coffee.

Honey production of honey bee (Hymenoptera: Apidae) colonies with high and low Varroa destructor (Acari: Varroidae) infestation rates in eastern Canada

AbstractThe objective of this study was to compare the honey yields of groups of honey bee (Hymenoptera: Apidae) colonies with high and low infestation rates of the mite Varroa destructor Anderson and Trueman (Acari: Varroidae). More than 150 colonies were screened for mite fall in early spring and again 16 weeks later. The 10 colonies with the lowest rates (L) and the 10 colonies with the highest rates (H) of mite population growth were selected. These 20 colonies were evaluated for mite infestation in adult bees and honey production. Adult bee infestation in the colonies of the H group was significantly higher than in the colonies of the L group. Additionally, H and L colonies differed significantly for honey production. L colonies produced 28.91 ± 2.34 kg of honey per hive versus 18.49 ± 0.77 kg for the group of H colonies. Furthermore, the mite infestation level of colonies measured as mite fall or as number of mites per 100 bees, was significantly correlated with honey production (r = −0.62, P < 0.05 and r = −0.76, P < 0.01, respectively). These results indicate that varroa mite populations significantly reduce honey yields in honey bee colonies in eastern Canada.

Automatic image analysis and spot classification for detection of fruit fly infestation in hyperspectral images of mangoes

Fruit fly infestation of mangos is a major concern for growers and exporters, leading to requirements for quarantine treatments such as vapor heat treatment or irradiation and subsequent reduction in quality and consumer acceptance. An on-line method for detection and removal of infested fruit would thus benefit producers and consumers. An algorithm has been developed to identify spots generated in hyperspectral images of mangoes infested with fruit fly larvae. The algorithm incorporates background removal, application of a Gaussian blur, thresholding, and particle count analysis to identify locations of infestations. Each of the four algorithm steps involves adjustable parameters which were iteratively tested to find the optimal combination for detection in terms of false positive and false negative results. For algorithm parameters selected to minimize false negative results, a false negative error rate of 1.0% was achieved with 11.1% false positive error and 6.0% overall error in heavily infested samples. For the same sample set, the lowest overall error rate achieved was 2.0%, with 1.0% false positive and 3.0% false negative. For samples with lower infestation rates, the error rates were much higher, the lowest overall error being 12.3%. This therefore demonstrates the feasibility of hyperspectral imaging for fruit fly detection while highlighting the need for technology with improved resolution and signal to noise ratio to allow detection of single larvae.

Life history and assessment of grapevine phylloxera leaf galling incidence on Vitis species in Uruguay

Grapevine phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera: Phylloxeridae) is a worldwide pest of Vitis species. It has forms that feed on leaves and roots. Root forms predominate on Vitis vinifera (L.) cultivars, while leaf forms predominate on Vitis species from its native American range. Recently, high densities of D. vitifoliae infestations in leaves of V. vinifera in Brazil, Peru, and Uruguay have been reported. The aims of this study were to determine the seasonal development of grape phylloxera, quantify infestation levels on V. vinifera leaves, and compare them with infestation levels on leaves of a rootstock of American origin. Studies were conducted in two vineyards in Uruguay from 2004–2007. Terminal shoots of 3309 C and Cabernet Sauvignon, Chardonnay, Tannat, Viognier, grafted onto resistant rootstock, were sampled weekly and leaves examined for gall presence and insect life stage. First galls were detected in early October; eggs began to appear within two weeks. Two oviposition peaks occurred by the end of December, and they coincided with bursts of shoot growth. On 3309C rootstock, oviposition peaks were more frequent than on the European cultivars. Based on thermal accumulation, D. vitifoliae could complete eight generations a year in Uruguay. Rootstock 3309C suffered the greatest damage but in some cases was similar to the European cultivars. Damage to Chardonnay, Cabernet Sauvignon and Viognier were also high. There were no galls on Tannat. The 2005–2006 season was characterized by low infestation rates caused by a prolonged drought that affected vegetative growth. There were also differences between vineyards, where the vigorous plants suffering more damage. Leaf galling phylloxera incidence and damage were mainly associated to the cultivar but plant vigor and environmental factors also contributed to increase the incidence.

The ectoparasite mite Varroa destructor Anderson and Trueman in southeastern Brazil apiaries: effects of the hygienic behavior of Africanized honey bees on infestation rates

In Brazil, the ectoparasitic mite of bees Varroa destructor Anderson and Trueman (Acari: Varroidae) remains at low levels of infestation causing no major damage. However, with the introduction and possible dominance of a new haplotype (K) of the mite, usually found in areas with high infestation rates (IR), it is necessary to monitor and select beehives that are resistant to the pest in order to avoid future problems. Several factors are listed as potentially being responsible for the dynamics of mite infestation, among which hygienic behavior (HB) stands out. In this context we sought to evaluate the HB of Africanized honey bees Apis mellifera L. (Hymenoptera: Apidae) compared with the mite IR in apiaries of two municipalities of southeastern Brazil (Taubaté and Viçosa). For the municipality of Taubaté, the average IR was 4.9% (3.4 to 5.8%), while the HB averaged 98.6% (96 to 100%). In Viçosa, the average mite IR was found to be 10.0% (5.4 to 21.0%) with an average value for HB of 57.7% (0 to 79.0%). Results from this research show that IR and HB were negatively correlated (R = -0.9627, P<0.01), suggesting that hives with higher HB have lower IR.

Crosstalk between above- and belowground herbivores is mediated by minute metabolic responses of the host Arabidopsis thaliana

Plants are frequently under attack by multiple herbivores and can be infested at their shoots as well as their roots. As a consequence, plant metabolites are readily induced, mediated by phytohormones such as salicylic acid and jasmonic acid. Thereby, cross-talk between signal transduction pathways may occur if different herbivores attack the plant simultaneously. In turn, modifications in the plant metabolic pattern can affect herbivores infesting local and systemic tissue. Here, an integrative approach combining metabolomics and performance experiments was used to study the induction of plant metabolites in Arabidopsis thaliana by the specialist aphid Brevicoryne brassicae feeding on shoots and the generalist nematode Heterodera schachtii infesting root tissue. In contrast to most other studies, low infestation rates typical for the decisive early stages of infestation were used. Moreover, the consequences of induction responses on plant-mediated indirect interactions between these herbivores were investigated. In aphid-treated plants, several metabolites including glucosinolates, important defence compounds of Brassicaceae, were reduced in the shoot, but only minute changes took part in the systemic root tissue. Primary metabolites as well as phytohormones were not altered 3 days post infestation. In contrast, nematodes did not evoke significant metabolic alterations locally or systemically. In accordance, nematode presence did not affect aphid population growth, whereas aphids mediated a considerably reduced nematode infestation. These results demonstrate that plants respond in a very fine-tuned way to different challenges. Although they show only minute systemic responses to low herbivore stress, these changes can have pronounced effects on plant-mediated interactions between herbivores.

Screening and selection of lentil (Lens Miller) germplasm resistant to seed bruchids (Bruchus spp.)

Seed weevil (Bruchus spp.) is one of the most damaging pests to lentil crop, and the current chemical treatments to control this insect present numerous disadvantages. In this work, we have searched for resistant or almost resistant lentil cultivars to be used as potential sources of genes for resistance to bruchids as a more sustainable and environmentally friendly approach to diminish harvest loss. Thus, a lentil germplasm collection of 571 accessions from 27 different countries, and including wild species was screened for susceptibility to seed bruchids under natural field conditions in Central Spain. Infestation was evaluated in comparison with a check (lentil cultivar ‘Lyda’) according to the number of eggs per pod and the infestation rate in seeds (IR). A large variation of IR (0–70 %) was observed among accessions although, in general, wild species were consistently less affected by bruchids than the check. A total of 32 accessions, including Lens culinaris Medikus subsp. culinaris, Lens culinaris Medikus subsp. orientalis (Boiss.) Ponert, Lensnigricans (M. Bieb.) Godr., and Lenslamottei Cezfr., showed lower infestation rates than the check and were selected as potential sources of resistance to this pest. Potential mechanisms of resistance of selected accessions and their inclusion in a breeding program are outlined.

IMPACT OF CERTAIN FACTORS AND AGRICULTURAL PRACTICES ON INFESTATION OF DATE PALM TREES BY THE RED PALM WEEVIL (RHYNCHOPHORUS FERRUGINEUS (OLIV.)

The aim of the present work was to study the Effect of certain agricultural practices on infestation of date palm by the red palm weevil (RPW)Rhynchophorus ferrugineus (Oliv.). Results showed that palm tree pruning without dusting with agricultural sulfur showed the highest infestation rate while, pruning of date palm and dusting with agricultural sulfur resulted in lower infestation rate. Flooding irrigation resulted in significantly higher infestation of date palm by RPW compared to dripping, which showed lower % infestation. The RPW infestation rates in date palm plantation were maximum in stem position of 0-50 cm. Meanwhile the lowest infestation rate was at the date palm top (growing area).Data also indicated that about 75%of date palm infestations were found at the first meter from the ground. The most susceptible date palm cultivars to RPW were seedling and Zaghloul followed by Samany and Hayany while the least susceptible cultivar was Amhat.

No experimental effects of parasite load on male mating behaviour and reproductive success

Parasites can negatively affect their host’s physiology and morphology and render host individuals less attractive as mating partners. The energetic requirements of defending against parasites have to be traded off against other needs such as feeding activity, territoriality, thermoregulation or reproduction. Parasites can affect mating patterns, with females preferentially mating with parasite-resistant or parasite-free partners. We tested experimentally whether removal of both ectoparasites and endoparasites on free-living, male Columbian ground squirrels, Urocitellus columbianus, affected male mating behaviour, reproductive success and seasonal and posthibernation weight gain compared to control males. We predicted that experimental males would lose less body mass and mate more often than control males. In addition, we predicted experimental males would copulate earlier than control males in the mating sequences of receptive females and sire more offspring, because this species exhibits a strong first-male paternity advantage. Parasite treatment significantly reduced the parasite loads of experimental males. None of these males had ectoparasites at the end of the season, compared to 70% infestation of the control males. However, contrary to our expectations, the experimental treatment did not affect male reproductive behaviour (mating frequency, mating position, consort duration and mate-guarding duration), did not increase male reproductive success, and did not influence male body mass. We conclude that parasite infestation plays a minor role in affecting male reproductive behaviour, maybe because of the overall low infestation rates. Alternatively, males may be able to compensate for any costs associated with moderate loads of parasites.

Pithy Protection: Nicotiana attenuata’s Jasmonic Acid-Mediated Defenses Are Required to Resist Stem-Boring Weevil Larvae

Folivory is the best studied plant-herbivore interaction, but it is unclear whether the signaling and resistance traits important for the defense of leaves are also important for other plant parts. Larvae of the tobacco stem weevil, Trichobaris mucorea, burrow into stems of Nicotiana attenuata and feed on the pith. Transgenic N. attenuata lines silenced in signaling and foliar defense traits were evaluated in a 2-year field study for resistance against attack by naturally occurring T. mucorea larva. Plants silenced in early jasmonic acid (JA) biosynthesis (antisense [as]-lipoxygenase3 [lox3]; inverted repeat [ir]-allene oxide cyclase), JA perception (as-coronatine insensitive1), proteinase inhibitors (ir-pi), and nicotine (ir-putrescine methyl-transferase) direct defenses and lignin (ir-cad) biosynthesis were infested more frequently than wild-type plants. Plants unable to emit C(6) aldehydes (as-hpl) had lower infestation rates, while plants silenced in late steps in JA biosynthesis (ir-acyl-coenzyme A oxidase, ir-opr) and silenced in diterpene glycoside production (ir-geranylgeranyl pyrophosphate synthase) did not differ from wild type. Pith choice assays revealed that ir-putrescine methyl-transferase, ir-coronatine insensitive1, and ir-lox3 pith, which all had diminished nicotine levels, were preferred by larvae compared to wild-type pith. The lack of preference for ir-lox2 and ir-cad piths, suggest that oviposition attraction and vascular defense, rather than pith palatability accounts for the higher attack rates observed for these plants. We conclude that traits that influence a plant's apparency, stem hardness, and pith direct defenses all contribute to resistance against this herbivore whose attack can be devastating to N. attenuata's fitness.

Modeling the dynamic transmission of dengue fever: investigating disease persistence.

BackgroundDengue is a disease of great complexity, due to interactions between humans, mosquitoes and various virus serotypes as well as efficient vector survival strategies. Thus, understanding the factors influencing the persistence of the disease has been a challenge for scientists and policy makers. The aim of this study is to investigate the influence of various factors related to humans and vectors in the maintenance of viral transmission during extended periods.Methodology/Principal FindingsWe developed a stochastic cellular automata model to simulate the spread of dengue fever in a dense community. Each cell can correspond to a built area, and human and mosquito populations are individually monitored during the simulations. Human mobility and renewal, as well as vector infestation, are taken into consideration. To investigate the factors influencing the maintenance of viral circulation, two sets of simulations were performed: (1st) varying human renewal rates and human population sizes and (2nd) varying the house index (fraction of infested buildings) and vector per human ratio. We found that viral transmission is inhibited with the combination of small human populations with low renewal rates. It is also shown that maintenance of viral circulation for extended periods is possible at low values of house index. Based on the results of the model and on a study conducted in the city of Recife, Brazil, which associates vector infestation with Aedes aegytpi egg counts, we question the current methodology used in calculating the house index, based on larval survey.Conclusions/SignificanceThis study contributed to a better understanding of the dynamics of dengue subsistence. Using basic concepts of metapopulations, we concluded that low infestation rates in a few neighborhoods ensure the persistence of dengue in large cities and suggested that better strategies should be implemented to obtain measures of house index values, in order to improve the dengue monitoring and control system.

Incidence and host range of the melon fruit fly Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) in Central Tanzania

The incidence and host range of the melon fruit fly, Bactrocera cucurbitae, was studied in the Morogoro Region of Central Tanzania between October 2004 and October 2006. Occurrence was limited to low to medium altitude locations. Populations reached a peak in the dry season, between July and September. Host plants belonged mostly to the Cucurbitaceae family, with non-cucurbit hosts being infested occasionally and at low infestation rate. Highly preferred cucurbit hosts were cucumber (Cucumis sativus), melon (Cucumis melo) and watermelon (Citrullus lanatus), while Momordica cf trifoliata was the most important wild host. Bactrocera cucurbitae appeared to dominate most indigenous cucurbit infesters, with the exception of Dacus ciliatus which was still dominant in some cucurbitaceous spp.

Density-Dependent and Density-Independent Mortality of the Western Corn Rootworm: Impact on Dose Calculations of Rootworm-Resistant Bt Corn

The percentage of viable eggs of the western corn rootworm, Diabrotica virgifera virgifera LeConte, which survived to the adult stage was evaluated for the effect of egg density in 2005 and 2007 in central Missouri. In 2005, each plot was 2.44 by 3.05 m and contained 64 maize (corn), Zea mays L., plants. In 2007, plots were 3.05 by 3.05 m and again contained 64 corn plants. Seven egg densities (2,400, 1,200, 600, 300, 100, 50, and 25 viable eggs per 30.5 cm) were evaluated with four to six replications in each year in a completely randomized design. In 2007 only, an additional row was infested near each plot to evaluate plant damage. In both years, there was no correlation of infestation level and percentage of emergence between infestation levels of 25-600 viable eggs per 30.5 cm, indicating that density-dependent mortality did not occur at these egg densities. In 2005, 8.04% of the viable eggs established on a corn plant and produced an adult at these lower infestation rates. In 2007, this value was 2.9%. Regardless of egg density, approximately 92-97% failed to establish and produce adults (density-independent mortality). In 2005 and in the combined analysis, as viable egg densities increased from 600 to 2400 per 30.5 cm there was a significant decrease in percentage of emergence. In a broken line analysis of the 2005 data, the point where density-dependent mortality began in the combined analysis was 851 eggs per 30.5 cm with a 95% confidence interval from 678 to 1024. That year density-dependent mortality was important at high infestations and killed 54.4% of those larvae that successfully established on a plant at the highest egg density. However, little or no density-dependent mortality occurred at infestation levels <850 viable eggs per 30.5 cm in either year of the study. Combining data from both years with all previously published data in a broken line analysis indicated that density-dependent mortality began at approximately 800 viable eggs per 30.5 cm. These data are discussed in terms of dose calculations for products targeting the western corn rootworm.

Host range and distribution of fruit-infesting pestiferous fruit flies (Diptera, Tephritidae) in selected areas of Central Tanzania

The host range of major fruit fly pests in Central Tanzania was evaluated from October 2004 to October 2006. Samples of 48 potential hosts were collected and incubated for fruit fly emergence. Bactrocera invadens was the dominant species in incidence expressed as the ratio of infested to total number samples collected, as well as infestation rate, expressed as number of flies emerging per unit weight. Eight new host fruits are reported. Infestation by native pests, such as Ceratitis capitata and C. cosyra, was minor compared to B. invadens. Ceratitis rosa was the dominant species in temperate fruits, and Cucurbitaceae were mainly infested by Bactrocera cucurbitae, a specialized cucurbit feeder. Among commercial fruits, high infestation incidences were observed in mango and guava, but they decreased throughout the fruiting season. Low infestation rates were observed in all Citrus species and in avocado, indicating these fruits as poor hosts for the studied fruit fly pests in this region. Widespread availability and abundance of fruit species studied here ensures year-round breeding of B. invadens. Seasonal infestation differs, with mango being the most important host in October to January, while guava being important from February to August. Tropical almond showed very high incidence and infestation rate for B. invadens and might act as an important reservoir host, bridging the fruiting seasons of mango and guava. Soursop acts as an important host for C. cosyra after the mango season. Ceratitis capitata is a pest of minor importance of the commercial fruits studied in this region.

Effectiveness of GF-120NF Fruit Fly Bait as a suppression tool forBactrocera latifrons(Diptera: Tephritidae)

Bactrocera latifrons (Hendel) is a tephritid fruit fly of primarily Asian distribution that has invaded Hawaii and, more recently, the continent of Africa (Tanzania and Kenya). It primarily infests solanaceous fruits, so has the potential to impact production of crops such as peppers (Capsicum annuum L. and Capsicum frutescens L.), eggplant (Solanum melongena L.), African eggplant (Solanum aethiopicum L.) and tomatoes (Solanum lycopersicum L.). Because little work has been done to develop suppression techniques for this fruit fly species, field cage tests of the effectiveness of a commercially available bait spray, GF-120NF Fruit Fly Bait, against wild B. latifrons were conducted. Sexually mature B. latifrons adults (75 male and 75 female) were introduced to both a control cage and a treatment cage, each of which held six fruiting Anaheim chili pepper (C. annuum L.) plants. Fruits were harvested, and assessed for infestation, both before and after the application of the bait spray in the treatment cage. There was no difference in infestation rate between control and treatment cages before the application of the bait spray, whereas there was a significantly lower infestation rate in treatment cages following the application of the bait spray. Post-spray infestation rate in the treatment cages (in two separate, replicated bioassays) was always zero and no live flies were detected in the treatment cages at the end of the trials. The results of this study provide evidence that GF-120NF Fruit Fly Bait should be effective in suppressing B. latifrons populations in the field.

Infestation and Population Dynamics of Insects on Stored Cassava and Yams Chips in Benin, West Africa

Natural insect infestation in cassava (Manihot esculenta Crantz subspecies esculenta) and yam (Dioscorea spp.) chips was evaluated during two consecutive storage seasons (2003-2004 and 2004-2005) in two agroecological zones of Benin (Northern Guinea Savanna [NGS] and Sudan Savanna [SS]). The insects infesting chips were collected, identified, and counted, they included Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae), Cathartus quadricollis (Guerin) (Coleoptera: Silvanidae), Carpophilus dimidiatus (F.) (Coleoptera: Nitidulidae), Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). P. truncatus and C. quadricollis were observed with a higher prevalence on cassava than on yam chips. During both seasons after 3 mo of storage, all (100%) cassava chip samples were infested with P. truncatus and C. quadricollis in both agroecological zones, whereas yam chips only showed lower infestation rates of 59.5 and 19.1% for P. truncatus and C. quadricollis, respectively, at the end of storage in 2003-2004. During the 2004-2005 season after 3 mo of storage infestation rate in yam chips was 66 and 24% in NGS and 100 and 0% in SS for P. truncatus and C. quadricollis, respectively, showing that insect infestation levels vary significantly with commodity, year, and fluctuate during the storage season.

A Relationship Between Avian Foraging Behavior and Infestation by Trombiculid Larvae (Acari) in Chiapas, Mexico

ABSTRACTBirds face varying risk from parasites as they select and utilize habitat. Unfortunately, behavioral and habitat correlates of parasitism in birds are not well documented. This study combines data from a foraging behavior study with results from a banding study to test whether behavior and habitat affect an ectoparasite infestation by trombiculid mite (chigger) larvae on the bird community found in two different coffee agroecosystems in Chiapas, Mexico. Individuals from bird species with regular prevalence (i.e., infestation) foraged more frequently in lower vegetative layers and had significantly lower foraging height than those from species with little or no prevalence, suggesting that foraging near the ground increases exposure risk to chigger larvae. Using linear regression, across species, parasite prevalence decreased with increasing average foraging height. Lower infestation rates were found in coffee agroecosystems with higher management intensity (i.e., less shade and drier conditions), suggesting that management activities influence infestation rates. Consequently, drier tropical habitats may pose less risk to birds from ectoparasites, though seasonal prevalence was highest during the winter dry season. Although no direct link was found between host condition and infestation by chigger larvae on the wintering grounds, birds were sampled during the middle of the over‐wintering period, not the end when infestation could affect birds fattening for migration.