Plant Pests of the Middle East

 

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The Department of Entomology
The Robert H. Smith Faculty of Agriculture, Food and Environment
The Hebrew University of Jerusalem
Herzl 229, Rehovot 7610001, ISRAEL

Tel: 08-9489223 
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Email: orlytal@savion.huji.ac.il

Publications

2017
Coll, M. ; Wajnberg, E. Environmental Pest Management. In Environmental Pest Management; Environmental Pest Management; John Wiley & Sons, Ltd, 2017; pp. 405-417. Publisher's VersionAbstract
Summary For thousands of years, farmers have protected their crops by combating one pest at a time, using a single control method with very little consideration of the surrounding environment. In its early form, Integrated Pest Management (IPM) was intended to provide a more holistic approach to pest management than the ‘supervised control’ that was commonplace at the time. However, when public support later declined, agro-chemical companies were quick to step in and take on a major role in directing pest management back towards supervised control. To reduce yield losses to pests and produce more food in sustainable and environmentally compatible ways, major long-term governmental commitments are needed. We argue that governmental inputs acting to promote sustainable agricultural practices and nature conservation should have four main thrusts that are currently missing in most legislation: (1) establishing goal-oriented agro-environmental schemes, (2) externalizing the true costs of pesticide use, (3) strengthening the public extension service, and (4) soliciting goal-specific research.
Coll, M. ; Wajnberg, E. Environmental Pest Management. In Environmental Pest Management; Environmental Pest Management; John Wiley & Sons, Ltd, 2017; pp. 1-17. Publisher's VersionAbstract
Summary Increasing awareness and concerns regarding the adverse effects of pest management activities on human health and the environment have led researchers and, to a lesser extent non-governmental activists and policymakers, to seek ways to restrain harmful pest control practices. Conservation biologists, in their efforts to protect biodiversity, have begun to document the importance of the environment in pest management. At the same time, the Integrated Pest Management (IPM) approach, formulated more than 55 years ago, has for the most part failed to fulfil its mission developing effective, safe and sustainable plant protection systems. To this end, a new pest management paradigm is needed: a top-down, system-centric approach should replace the historical bottom-up, pest-centric viewpoint. This change is particularly important if we are to harness pest control activities to a global effort to increase food security and environmental protection.
Coll, M. ; Wajnberg, E. Environmental Pest Management: Challenges for Agronomists, Ecologists, Economists and Policymakers; John Wiley & Sons, Ltd, 2017. Publisher's VersionAbstract

A wide-ranging, interdisciplinary exploration of key topics that interrelate pest management, public health and the environment

This book takes a unique, multidimensional approach to addressing the complex issues surrounding pest management activities and their impacts on the environment and human health, and environmental effects on plant protection practices.

It features contributions by a distinguished group of authors from ten countries, representing an array of disciplines. They include plant protection scientists and officers, economists, agronomists, ecologists, environmental and public health scientists and government policymakers. Over the course of eighteen chapters, those experts share their insights into and analyses of an array of issues of vital concern to everyone with a professional interest in this important subject.

The adverse effects of pest control have become a subject of great concern worldwide, and researchers and enlightened policymakers have at last begun to appreciate the impact of environmental factors on our ability to manage pest populations. Moreover, while issues such as pesticide toxicity have dominated the global conversation about pest management, economic and societal considerations have been largely neglected. Environmental Pest Management: Challenges for Agronomists, Ecologists, Economists and Policymakers is the first work to provide in-depth coverage of all of these pressing issues between the covers of one book.

• Offers a unique multi-dimensional perspective on the complex issues surrounding pest management activities and their effect on the environment and human health

• Addresses growing concerns about specific pest management strategies, including the use of transgenic crops and biological controls

• Analyses the influence of global processes, such as climate change, biological invasions and shifts in consumer demand, and ecosystem services and disservices on pest suppression efforts

• Explores public health concerns regarding biodiversity, pesticide use and food safety

• Identifies key economic drivers of pest suppression research, strategies and technologies

• Proposes new regulatory approaches to create sustainable and viable crop protection systems in the framework of agroenvironmental schemes

Offering a timely and comprehensively-unique treatment of pest management and its environmental impacts in a single, interdisciplinary volume, this book is a valuable resource for scientists in an array of disciplines, as well as government officials and policymakers. Also, teachers of undergraduate and graduate level courses in a variety of fields are sure to find it a highly useful teaching resource.

Schuldiner-harpaz, T. ; Coll, M. Estimating the effect of plant-provided food supplements on pest consumption by omnivorous predators: lessons from two coccinellid beetles. Pest Manag Sci 2017, 73, 976-983.Abstract
BACKGROUND: Plant-provided food supplements can influence biological pest control by omnivorous predators in two counteracting ways: they can (i) enhance predator populations, but (ii) reduce pest consumption by individual predators. Yet the majority of studies address only one of these aspects. Here, we first tested the influence of canola (Brassica napus L.) pollen supplements on the life history of two ladybeetle species: Hoppodamia variegata (Goeze) and Coccinella septempunctata (L.). We then developed a theoretical model to simulate total pest consumption in the presence and absence of pollen supplements. RESULTS: Supplementing a prey diet with canola pollen increased H. variegata larval survival from 50 to 82%, and C. septempunctata female oviposition by 1.6-fold. Model simulations revealed a greater benefit of pollen supplements when relying on C. septempunctata for pest suppression than on H. variegata. CONCLUSION: For these two predators, the tested pollen serves as an essential supplement to a diet of prey. However, the benefit of a mixed prey-pollen diet was not always sufficient to overcome individual decrease in pest consumption. Taken together, our study highlights the importance of addressing both positive and negative roles of plant-provided food supplements in considering the outcome for biological control efforts that rely on omnivorous predators. © 2016 Society of Chemical Industry.
Zarchin, S. ; Dag, A. ; Salomon, M. ; Hendriksma, H. P. ; Shafir, S. Honey bees dance faster for pollen that complements colony essential fatty acid deficiency. Behavioral Ecology and Sociobiology 2017, 71, 172. Publisher's VersionAbstract
Honey bee colonies require adequate pollen for maintenance and growth. Pollens vary in nutritional value, and a balanced diet is achieved by mixing pollens with complementary essential nutrients. We tested subjective evaluation of pollens by foragers in colonies deprived of one of two essential fatty acids (eFAs), alpha-linolenic acid (omega-3) or linoleic acid (omega-6). We used four pollens, two rich in omega-3 and two rich in omega-6. A colony in an observation hive was allowed to forage for 2–5 days on a single pollen source. The following day, we repeatedly presented one of three pollens: the same pollen that the bees had been collecting the previous days, a novel pollen that was similarly deficient in omega-3 or omega-6, and a novel pollen that complemented their eFA deficiency. We measured the rate of waggle dances, which reflects on the strength of recruitment effort, of foragers returning to the observation hive from each of the pollens. Dance rates did not differ between the four pollens, but they were the highest to the ``complementary'' pollen and the lowest to the ``same'' pollen. Furthermore, this effect was greater for pollen combinations with greater eFA disparity between the same and the complementary pollens. Our findings support the ability of bees to balance colony eFA intake. Conditioning of the proboscis extension response (PER) tests showed that pollen foragers discriminated well between the four pollen odors, but the mechanisms by which bees assess pollen eFA composition remain to be elucidated. Differential dancing would recruit foragers to pollens that balance colony nutritional needs.
Yuval, B. Symbiosis: Gut Bacteria Manipulate Host Behaviour. Current Biology 2017, 27, R746 - R747. Publisher's VersionAbstract
Summary Bacteria resident in the gut of Drosophila modify the fly’s innate chemosensory responses to nutritional stimuli. In effect, the gut microbiome compels the host to forage on food patches that favour particular assemblages of bacteria.
Sapir, G. ; Baras, Z. ; Azmon, G. ; Goldway, M. ; Shafir, S. ; Allouche, A. ; STERN, E. ; Stern, R. A. Synergistic effects between bumblebees and honey bees in apple orchards increase cross pollination, seed number and fruit size. Scientia Horticulturae 2017, 219, 107 - 117. Publisher's VersionAbstract
Most apple cultivars are self-sterile and completely dependent on cross-pollination from a different cultivar in order to set fruit. Various insects may be pollinators, but the main one is the honey bee [HB] (Apis mellifera). However, despite the advantages of the honey bee as pollinator of many plants, it is a relatively inefficient pollinator of apple flowers. The main reason for this is the tendency of HBs to visit the apple flower from the side (sideworker), thus “stealing” nectar without touching the flower’s reproductive organs – stamens and stigma. In contrast, a bee that visits the flower from the top (topworker) contacts the flower’s reproductive organs, which results in better pollination. Due to the low pollination efficiency, few seeds are formed, and often the resulting fruit is too small to be of commercial value. Experiments conducted in Israel over the last few years have shown for the first time that adding bumblebees [BB] (Bombus terrestris) into pear orchards improved cross-pollination, thus increasing the number of seeds and subsequently fruit size. The goal of the present work was to test the hypothesis that adding BBs to apple orchards may improve cross-pollination. We found that adding BBs to the HBs in the apple orchard improved pollination in all tested cultivars, especially in ‘Gala’, which naturally suffers from relatively few seeds in the fruit. It appears that the addition of BBs did not only increase the number of pollinating insects in the orchard that could perform cross-pollination, including in the cool mornings and in adverse weather conditions, but that it also changed HB foraging behavior, which resulted in improved cross-pollination and increased efficiency, and subsequently more seeds and larger fruit. The improved pollination was due to the greater mobility of HBs between rows of pollinated cultivar and pollenizer, and to the greater proportion of topworkers, which are more efficient pollinators.
Santos-Garcia, D. ; Silva, F. J. ; Morin, S. ; Dettner, K. ; Kuechler, S. M. The All-Rounder Sodalis: A New Bacteriome-Associated Endosymbiont of the Lygaeoid Bug Henestaris halophilus (Heteroptera: Henestarinae) and a Critical Examination of Its Evolution. Genome Biology and Evolution 2017, 9 2893 - 2910. Publisher's VersionAbstract
Hemipteran insects are well-known in their ability to establish symbiotic relationships with bacteria. Among them, heteropteran insects present an array of symbiotic systems, ranging from the most common gut crypt symbiosis to the more restricted bacteriome-associated endosymbiosis, which have only been detected in members of the superfamily Lygaeoidea and the family Cimicidae so far. Genomic data of heteropteran endosymbionts are scarce and have merely been analyzed from the Wolbachia endosymbiont in bed bug and a few gut crypt-associated symbionts in pentatomoid bugs. In this study, we present the first detailed genomic analysis of a bacteriome-associated endosymbiont of a phytophagous heteropteran, present in the seed bug Henestaris halophilus (Hemiptera: Heteroptera: Lygaeoidea). Using phylogenomics and genomics approaches, we have assigned the newly characterized endosymbiont to the Sodalis genus, named as Candidatus Sodalis baculum sp. nov. strain kilmister. In addition, our findings support the reunification of the Sodalis genus, currently divided into six different genera. We have also conducted comparative analyses between 15 Sodalis species that present different genome sizes and symbiotic relationships. These analyses suggest that Ca. Sodalis baculum is a mutualistic endosymbiont capable of supplying the amino acids tyrosine, lysine, and some cofactors to its host. It has a small genome with pseudogenes but no mobile elements, which indicates middle-stage reductive evolution. Most of the genes in Ca. Sodalis baculum are likely to be evolving under purifying selection with several signals pointing to the retention of the lysine/tyrosine biosynthetic pathways compared with other Sodalis.
Sparks, J. T. ; Bohbot, J. D. ; Ristić, M. ; Mišić, D. ; Skorić, M. ; Mattoo, A. ; Dickens, J. C. Chemosensory Responses to the Repellent Nepeta Essential Oil and Its Major Component Nepetalactone by Aedes aegypti (Diptera: Culicidae), a Vector of Zika Virus. Journal of Medical Entomology 2017, 54, 957 - 963. Publisher's VersionAbstract
Nepeta essential oil (Neo; catnip) and its major component, nepetalactone, have long been known to repel insects including mosquitoes. However, the neural mechanisms through which these repellents are detected by mosquitoes, including the yellow fever mosquito Aedes aegypti (L.), an important vector of Zika virus, were poorly understood. Here we show that Neo volatiles activate olfactory receptor neurons within the basiconic sensilla on the maxillary palps of female Ae. aegypti. A gustatory receptor neuron sensitive to the feeding deterrent quinine and housed within sensilla on the labella of females was activated by both Neo and nepetalactone. Activity of a second gustatory receptor neuron sensitive to the feeding stimulant sucrose was suppressed by both repellents. Our results provide neural pathways for the reported spatial repellency and feeding deterrence of these repellents. A better understanding of the neural input through which female mosquitoes make decisions to feed will facilitate design of new repellents and management strategies involving their use.
Schuldiner-harpaz, T. ; Coll, M. Effect of Diet History on Prey and Pollen Food Choice by Two Lady Beetle Species. Journal of Insect Behavior 2017, 30, 432-438. Publisher's VersionAbstract
Mixed diets of prey and plant-provided foods, such as pollen, have been shown to benefit a wide range of arthropods. However, diet shifting between these two very different food sources remains poorly understood. We hypothesized that previous diet should influence subsequent time allocation between prey and plant food types; to reach a balanced diet, consumers are expected to allocate more time to resources previously lacking in their diet. We tested this hypothesis by observing the foraging choices of larvae of two omnivorous coccinellid species: Coccinella septempunctata L. and Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae), following a diet history of prey, pollen or a mixed diet of both food types. Results showed an asymmetrical tendency of C. septempunctata larvae to complement their previous diet with unfamiliar food: larvae allocated more time to pollen feeding, but not to prey, when each of the foods was previously absent from their diet. Study results have important implications for the use of plant-provided food supplements to enhance biological control by these omnivorous consumers.
Ben-Yosef, M. ; Zaada, D. S. Y. ; Dudaniec, R. Y. ; Pasternak, Z. ; Jurkevitch, E. ; Smith, R. J. ; Causton, C. E. ; Lincango, M. P. ; Tobe, S. S. ; Mitchell, J. G. ; et al. Host-specific associations affect the microbiome of Philornis downsi, an introduced parasite to the Galápagos Islands. Mol Ecol 2017, 26, 4644-4656.Abstract
The composition and diversity of bacteria forming the microbiome of parasitic organisms have implications for differential host pathogenicity and host-parasite co-evolutionary interactions. The microbiome of pathogens can therefore have consequences that are relevant for managing disease prevalence and impact on affected hosts. Here, we investigate the microbiome of an invasive parasitic fly Philornis downsi, recently introduced to the Galápagos Islands, where it poses extinction threat to Darwin's finches and other land birds. Larvae infest nests of Darwin's finches and consume blood and tissue of developing nestlings, and have severe mortality impacts. Using 16s rRNA sequencing data, we characterize the bacterial microbiota associated with P. downsi adults and larvae sourced from four finch host species, inhabiting two islands and representing two ecologically distinct groups. We show that larval and adult microbiomes are dominated by the phyla Proteobacteria and Firmicutes, which significantly differ between life stages in their distributions. Additionally, bacterial community structure significantly differed between larvae retrieved from strictly insectivorous warbler finches (Certhidea olivacea) and those parasitizing hosts with broader dietary preferences (ground and tree finches, Geospiza and Camarhynchus spp., respectively). Finally, we found no spatial effects on the larval microbiome, as larvae feeding on the same host (ground finches) harboured similar microbiomes across islands. Our results suggest that the microbiome of P. downsi changes during its development, according to dietary composition or nutritional needs, and is significantly affected by host-related factors during the larval stage. Unravelling the ecological significance of bacteria for this parasite will contribute to the development of novel, effective control strategies.
Pavlidi, N. ; Gioti, A. ; Wybouw, N. ; Dermauw, W. ; Ben-Yosef, M. ; Yuval, B. ; Jurkevitch, E. ; Kampouraki, A. ; Van Leeuwen, T. ; Vontas, J. Transcriptomic responses of the olive fruit fly Bactrocera oleae and its symbiont Candidatus Erwinia dacicola to olive feeding. Sci Rep 2017, 7 42633.Abstract
The olive fruit fly, Bactrocera oleae, is the most destructive pest of olive orchards worldwide. The monophagous larva has the unique capability of feeding on olive mesocarp, coping with high levels of phenolic compounds and utilizing non-hydrolyzed proteins present, particularly in the unripe, green olives. On the molecular level, the interaction between B. oleae and olives has not been investigated as yet. Nevertheless, it has been associated with the gut obligate symbiotic bacterium Candidatus Erwinia dacicola. Here, we used a B.oleae microarray to analyze the gene expression of larvae during their development in artificial diet, unripe (green) and ripe (black) olives. The expression profiles of Ca. E. dacicola were analyzed in parallel, using the Illumina platform. Several genes were found overexpressed in the olive fly larvae when feeding in green olives. Among these, a number of genes encoding detoxification and digestive enzymes, indicating a potential association with the ability of B. oleae to cope with green olives. In addition, a number of biological processes seem to be activated in Ca. E. dacicola during the development of larvae in olives, with the most notable being the activation of amino-acid metabolism.
2016
Kark, S. ; Sutherland, W. J. ; Shanas, U. ; Klass, K. ; Achisar, H. ; Dayan, T. ; Gavrieli, Y. ; Justo-Hanani, R. ; Mandelik, Y. ; Orion, N. ; et al. Priority questions and horizon scanning for conservation: A comparative study. PLoS ONE 2016, 11. Publisher's Version
Zidon, R. ; Tsueda, H. ; Morin, E. ; Morin, S. Projecting pest population dynamics under global warming: the combined effect of inter- and intra-annual variations. Ecological Applications 2016, 26, 1198-1210. Publisher's VersionAbstract
AbstractThe typical short generation length of insects makes their population dynamics highly sensitive not only to mean annual temperatures but also to their intra-annual variations. To consider the combined effect of both thermal factors under global warming, we propose a modeling framework that links general circulation models (GCMs) with a stochastic weather generator and population dynamics models to predict species population responses to inter- and intra-annual temperature changes. This framework was utilized to explore future changes in populations of Bemisia tabaci, an invasive insect pest-species that affects multiple agricultural systems in the Mediterranean region. We considered three locations representing different pest status and climatic conditions: Montpellier (France), Seville (Spain), and Beit-Jamal (Israel). We produced ensembles of local daily temperature realizations representing current and future (mid-21st century) climatic conditions under two emission scenarios for the three locations. Our simulations predicted a significant increase in the average number of annual generations and in population size, and a significant lengthening of the growing season in all three locations. A negative effect was found only in Seville for the summer season, where future temperatures lead to a reduction in population size. High variability in population size was observed between years with similar annual mean temperatures, suggesting a strong effect of intra-annual temperature variation. Critical periods were from late spring to late summer in Montpellier and from late winter to early summer in Seville and Beit-Jamal. Although our analysis suggested that earlier seasonal activity does not necessarily lead to increased populations load unless an additional generation is produced, it is highly likely that the insect will become a significant pest of open-fields at Mediterranean latitudes above 40° during the next 50 years. Our simulations also implied that current predictions based on mean temperature anomalies are relatively conservative and it is better to apply stochastic tools to resolve complex responses to climate change while taking natural variability into account. In summary, we propose a modeling framework capable of determining distinct intra-annual temperature patterns leading to large or small population sizes, for pest risk assessment and management planning of both natural and agricultural ecosystems.
Hendriksma, H. P. ; Shafir, S. Honey bee foragers balance colony nutritional deficiencies. 2016, 70, 509 - 517. Publisher's VersionAbstract
Honey bee colonies, foraging predominantly on a single pollen source, may encounter nutritional deficits. In the present study, we examined the nutritional resilience of honey bee colonies, testing whether foragers shift their foraging effort towards resources that complement a nutritional deficit. Eight honey bee colonies were kept in screened enclosures and fed for 1 week a pollen substitute diet deficient in a particular essential amino acid. Foragers were subsequently tested for a preference between the same diet previously fed, a different diet that was similarly deficient, or a diet that complemented the deficiency. Foragers preferred the complementary diet over the same or similar diets. Appetitive conditioning tests showed that bees were able to discriminate also between the same and similar diets. Overall, our results support the hypothesis that honey bees prefer dietary diversity, and that they do not just include novel sources but specifically target nutritionally complementary ones. Whereas we specifically focused on deficiencies in essential amino acids, we cannot rule out that bees were also complementing correlated imbalances in other nutrients, most notably essential fatty acids. The ability of honey bees to counter deficient nutrition contributes to the mechanisms which social insects use to sustain homeostasis at the colony level.
Hall, A. B. ; Papathanos, P. A. ; Sharma, A. ; Cheng, C. ; Akbari, O. S. ; Assour, L. ; Bergman, N. H. ; Cagnetti, A. ; Crisanti, A. ; Dottorini, T. ; et al. Radical remodeling of the Y chromosome in a recent radiation of malaria mosquitoes. Proceedings of the National Academy of Sciences 2016, 113, E2114–E2123. Publisher's VersionAbstract
Interest in male mosquitoes has been motivated by the potential to develop novel vector control strategies, exploiting the fact that males do not feed on blood or transmit diseases, such as malaria. However, genetic studies of male Anopheles mosquitoes have been impeded by the lack of molecular characterization of the Y chromosome. Here we show that the Anopheles gambiae Y chromosome contains a very small repertoire of genes, with massively amplified tandem arrays of a small number of satellites and transposable elements constituting the vast majority of the sequence. These genes and repeats evolve rapidly, bringing about remodeling of the Y, even among closely related species. Our study provides a long-awaited foundation for studying mosquito Y chromosome biology and evolution.Y chromosomes control essential male functions in many species, including sex determination and fertility. However, because of obstacles posed by repeat-rich heterochromatin, knowledge of Y chromosome sequences is limited to a handful of model organisms, constraining our understanding of Y biology across the tree of life. Here, we leverage long single-molecule sequencing to determine the content and structure of the nonrecombining Y chromosome of the primary African malaria mosquito, Anopheles gambiae. We find that the An. gambiae Y consists almost entirely of a few massively amplified, tandemly arrayed repeats, some of which can recombine with similar repeats on the X chromosome. Sex-specific genome resequencing in a recent species radiation, the An. gambiae complex, revealed rapid sequence turnover within An. gambiae and among species. Exploiting 52 sex-specific An. gambiae RNA-Seq datasets representing all developmental stages, we identified a small repertoire of Y-linked genes that lack X gametologs and are not Y-linked in any other species except An. gambiae, with the notable exception of YG2, a candidate male-determining gene. YG2 is the only gene conserved and exclusive to the Y in all species examined, yet sequence similarity to YG2 is not detectable in the genome of a more distant mosquito relative, suggesting rapid evolution of Y chromosome genes in this highly dynamic genus of malaria vectors. The extensive characterization of the An. gambiae Y provides a long-awaited foundation for studying male mosquito biology, and will inform novel mosquito control strategies based on the manipulation of Y chromosomes.
Galizi, R. ; Hammond, A. ; Kyrou, K. ; Taxiarchi, C. ; Bernardini, F. ; O’Loughlin, S. M. ; Papathanos, P. A. ; Nolan, T. ; Windbichler, N. ; Crisanti, A. A CRISPR-Cas9 sex-ratio distortion system for genetic control. 2016, 6 31139. Publisher's VersionAbstract
Genetic control aims to reduce the ability of insect pest populations to cause harm via the release of modified insects. One strategy is to bias the reproductive sex ratio towards males so that a population decreases in size or is eliminated altogether due to a lack of females. We have shown previously that sex ratio distortion can be generated synthetically in the main human malaria vector Anopheles gambiae, by selectively destroying the X-chromosome during spermatogenesis, through the activity of a naturally-occurring endonuclease that targets a repetitive rDNA sequence highly-conserved in a wide range of organisms. Here we describe a CRISPR-Cas9 sex distortion system that targets ribosomal sequences restricted to the member species of the Anopheles gambiae complex. Expression of Cas9 during spermatogenesis resulted in RNA-guided shredding of the X-chromosome during male meiosis and produced extreme male bias among progeny in the absence of any significant reduction in fertility. The flexibility of CRISPR-Cas9 combined with the availability of genomic data for a range of insects renders this strategy broadly applicable for the species-specific control of any pest or vector species with an XY sex-determination system by targeting sequences exclusive to the female sex chromosome.
Malka, O. ; Shekhov, A. ; Reichelt, M. ; Gershenzon, J. ; Vassão, D. G. ; Morin, S. Glucosinolate Desulfation by the Phloem-Feeding Insect Bemisia tabaci. Journal of Chemical Ecology 2016, 42, 230–235. Publisher's VersionAbstract
Glucosinolates are plant secondary defense metabolites confined nearly exclusively to the order Brassicales. Upon tissue rupture, glucosinolates are hydrolyzed to various bioactive breakdown products by the endogenous plant enzyme myrosinase. As the feeding of chewing insect herbivores is associated with plant tissue damage, these insects have developed several independent strategies for coping with the glucosinolate-myrosinase defense system. On the other hand, our knowledge of how phloem-feeding insects interact with the glucosinolate-myrosinase system is much more limited. In fact, phloem feeders might avoid contact with myrosinase altogether so their susceptibility to intoxication by glucosinolate hydrolysis products is unclear. Previous studies utilizing Arabidopsis thaliana plants accumulating high levels of aliphatic- or indolic-glucosinolates indicated that both glucosinolate groups have moderate negative effects on the reproductive performance of Bemisia tabaci, a generalist phloem-feeding insect. To get a deeper understanding of the interaction between B. tabaci and glucosinolate-defended plants, adults were allowed to feed on artificial diet containing intact glucosinolates or on Brussels sprout and A. thaliana plants, and their honeydew was analyzed for the presence of possible metabolites. We found that B. tabaci is capable of cleaving off the sulfate group of intact glucosinolates, producing desulfoglucosinolates that cannot be activated by myrosinases, a mechanism described to date only in several chewing insect herbivores. The presence of desulfated glucosinolates in the honeydew of a generalist phloem-feeder may indicate the necessity to detoxify glucosinolates, likely due to some level of cellular damage during feeding, which results in glucosinolate activation, or as a mechanism to circumvent the non-enzymatic breakdown of indolic glucosinolates.
Roditakis, E. ; Morin, S. ; Baixeras, J. Is Bactra bactrana (Kennel, 1901) a novel pest of sweet peppers?. Bulletin of Entomological Research 2016, 106, 161-167. Publisher's VersionAbstract
This is the first report of Bactra bactrana (Kennel, 1901) (Lepidoptera: Tortricidae) attacking a major solanaceous crop, sweet pepper Capsicum annuum L. The infestation was detected in two greenhouses at the area of Tympaki (Southern Crete, Greece). The moth larvae caused typical symptoms of a fruit borer with numerous small holes on the surface of the peppers and extensive damage on the inside of the fruit as a result of the feeding activity. Unknown factors facilitated this major shift in host range since B. bactrana is typically a stem borer of sedges. In addition, the pest status of B. bactrana is currently under question, as in both cases the infestations by the moth were associated with significant yield losses. B. bactrana was moderately controlled with chemicals registered for Lepidoptera management in sweet pepper due to the boring nature of the infestation. Some comparative taxonomic notes are provided to facilitate accurate pest discrimination of related Bactra species. Finally, biological attributes of the species are summarized and are discussed from pest control and ecological perspectives. Because Bactra species have been used in augmentative releases for the control of sage, the implications of our findings on the release of biocontrol agents are placed in perspective.
Rader, R. ; Bartomeus, I. ; Garibaldi, L. A. ; Garratt, M. P. D. ; Howlett, B. G. ; Winfree, R. ; Cunningham, S. A. ; Mayfield, M. M. ; Arthur, A. D. ; Andersson, G. K. S. ; et al. Non-bee insects are important contributors to global crop pollination. Proceedings of the National Academy of Sciences 2016, 113, 146–151. Publisher's VersionAbstract
Many of the world’s crops are pollinated by insects, and bees are often assumed to be the most important pollinators. To our knowledge, our study is the first quantitative evaluation of the relative contribution of non-bee pollinators to global pollinator-dependent crops. Across 39 studies we show that insects other than bees are efficient pollinators providing 39% of visits to crop flowers. A shift in perspective from a bee-only focus is needed for assessments of crop pollinator biodiversity and the economic value of pollination. These studies should also consider the services provided by other types of insects, such as flies, wasps, beetles, and butterflies—important pollinators that are currently overlooked.Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25–50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.