Bruchidae Research Articles

Identify immune-related genes of adzuki bean weevil (Callosobruchus chinensis) in response to bacteria challenge by transcriptome analysis

BackgroundCallosobruchus chinensis is one of the important postharvest pests in legume growing areas. Bacterial pesticide is a potential alternative method to control storage pests. However, the effect of these pathogen bacteria on storage pests, and the molecular mechanisms of insect response remain to be to investigated. ResultsUsing the next generation sequencing technology, we established a transcriptomic library for C. chinensis larvae in response to Escherichia coli. Total of 355 differential expressed genes (DEGs) were identified, which 178 DEGs were upregulated, and 177 DEGs were downregulated compared to control group. To validate the RNA-seq analysis, 20 DEGs and 14 immune-related genes were selected to perform quantitative polymerase chain reaction (RT-qPCR). These immune-related genes were involved in recognition (peptidoglycan recognition proteins), signal transduction (fibrinogen-related proteins, serine proteinases and NF-κB), and execution effectors (phenoloxidase, defensin, attacin, and antimicrobial peptide). In addition, genes that encode digestive and respiratory enzymes were altered in C. chinensis larvae in response to infection. Some genes that involved in juvenile hormone and insulin pathway appeared to express differentially, suggesting that pathogen infection might lead to developmental arrest. Furthermore, iron homeostasis and chitin metabolism appeared significantly altered after infection. ConclusionIn this study, we characterized the immune response of C. chinensis larvae in response to E. coli using RNA-seq, from pathogen recognition, signal transduction, to execution. Some other identified genes were involved in iron homeostasis, respiration, and digestion. A better understanding of molecular response of beetle to pathogen will facilitate us to develop an available strategy to control storage pests.

Bruchid beetle ovipositioning mediated defense responses in black gram pods

BackgroundBlack gram [Vigna mungo (L)] seeds are a rich source of digestible protein and dietary fibre, both for human and animal consumption. However, the quality and quantity of the Vigna seeds are severely affected by bruchid beetles during storage. Therefore, analyses of the expression of the bruchid induced transcript dynamics in black gram pods would be helpful to understand the underlying defense mechanism against bruchid oviposition.ResultsWe used the RNAseq approach to survey the changes in transcript profile in the developing seeds of a moderately resistant cultivar IC-8219 against bruchid oviposition using a susceptible cultivar T-9 as a control. A total of 96,084,600 and 99,532,488 clean reads were generated from eight (4 each) samples of IC-8219 and T-9 cultivar, respectively. Based on the BLASTX search against the NR database, 32,584 CDSs were generated of which 31,817 CDSs were significantly similar to Vigna radiata, a close relative of Vigna mungo. The IC-8219 cultivar had 630 significantly differentially expressed genes (DEGs) of which 304 and 326 genes up and down-regulated, respectively. However, in the T-9 cultivar, only 168 DEGs were identified of which 142 and 26 genes up and down-regulated, respectively. The expression analyses of 10 DEGs by qPCR confirmed the accuracy of the RNA-Seq data. Gene Ontology and KEGG pathway analyses helped us to better understand the role of these DEGs in oviposition mediated defense response of black gram. In both the cultivars, the most significant transcriptomic changes in response to the oviposition were related to the induction of defense response genes, transcription factors, secondary metabolites, enzyme inhibitors, and signal transduction pathways. It appears that the bruchid ovipositioning mediated defense response in black gram is induced by SA signaling pathways and defense genes such as defensin, genes for secondary metabolites, and enzyme inhibitors could be potential candidates for resistance to bruchids.ConclusionWe generated a transcript profile of immature black gram pods upon bruchid ovipositioning by de novo assembly and studied the underlying defense mechanism of a moderately resistant cultivar.

Molecular characterization of pests (Chrysomelidae: Bruchinae) of beans (Phaseolus vulgaris) in the Republic of Congo

The bean Phaseolus vulgaris is widely consumed by the Congolese population, because it is rich in protein and has a good nutritional quality. Beetles of the subfamily Bruchinae are pests of bean seeds in the field and storage in the Republic of Congo (RC). Their attacks cause a reduction in seed weight, leading to a decrease in the nutritional and commercial value of the seeds. The purpose of our study was to identify the post-harvest diversity of bean bruchids in two bean producing regions in the Congo (Niari and Bouenza) using molecular taxonomy (12S rRNA marker). The bean weevil, Acanthoscelides obtectus (Say), and cowpea weevil, Callosobruchus maculatus (Fabricius), were identified. Acanthoscelides obtectus, recognised as the main pest of beans, was found in all ten localities sampled, whereas C. maculatus, recognised as the main pest of pigeon peas (Cajanus cajan) and chickpeas (Cicer arietinum), was found in two of the ten. Better knowledge of the diversity of bruchids present in the RC will make it possible to propose effective control methods with little impact on environmental and human health.

Ekonomski zanačajne štetočine pasulja u Srbiji

Insects represent a limiting factor in the cultivation of beans (Phaseolus vulgaris L.) in most of the production regions, and often are the main cause of low productivity. During the vegetation, beans, as well as other legumes, are susceptible to the attack of numerous pests. The most significant are soil-dwelling, such as wireworms (fam. Elateridae), and storage pests like the bean weevil (Acanthoscelides obtectus Say). In addition to these two groups of insects, during the season, pests of the aboveground part such as aphids, thrips, stink bugs, and in dry years, mites, often occur causing significant losses.

Sementes de Senegalia polyphylla (Fabaceae) atacadas por bruquíneos podem ser viáveis?

Este trabalho teve por objetivo analisar a germinação de sementes de Senegalia polyphylla (DC.) Britton & Rose (Fabaceae) atacadas por bruquíneos (Coleoptera: Chrysomelidae: Bruchinae). Frutos dessa espécie foram coletados em São Gonçalo do Rio Preto, MG. As sementes indenes e as danificadas por bruquíneos foram submetidas aos testes de germinação em cinco tratamentos, com 100 sementes cada. O melhor percentual de germinação foi obtido nas sementes sadias e lixadas. As sementes sadias embebidas em água apresentaram baixo percentual de germinação. O ataque de bruquíneos proporcionou redução na taxa de germinação, mas não impediu que esse processo ocorresse nas sementes danificadas.

Resistance of Phaseolus vulgaris genotypes to Zabrotes subfasciatus (Coleoptera: Chrysomelidae: Bruchinae): categories and mechanisms

Information on Phaseolus vulgaris L. resistance categories and mechanisms to the Mexican bean weevil Zabrotes subfasciatus Boheman (Coleoptera: Chrysomelidae: Bruchinae) is important for breeding and subsequent commercialization of improved P. vulgaris genotypes. Using resistant genotypes in the bruchid beetles control may reduce insecticide applications, environmental risks, and production costs. Therefore, the objective of this study was to evaluate antixenosis and antibiosis of P. vulgaris genotypes to Z. subfasciatus and the relation of bromatological components on resistance. Free- and no-choice tests were carried out in a climate-controlled room (temperature 25 ± 1 °C, relative humidity 70 ± 10%, and 12:12 h light:dark photoperiod). Host selection for oviposition, total and viable numbers of eggs, emerged adults, egg to adult period (life cycle), adult longevity, and dry mass consumed of Z. subfasciatus were evaluated on 10 P. vulgaris genotypes. Bean samples of P. vulgaris genotypes were subjected to a bromatological analysis to determine possible resistance mechanisms. In the oviposition antixenosis, none of the P. vulgaris genotypes showed resistance to Z. subfasciatus. Contrastingly, the genotypes Raz 59, 173, 177, 179, 283, 284, 361, and 364 showed resistance in the categories of feeding antixenosis and/or antibiosis to Z. subfasciatus. On average, these genotypes reduced the number of emerged adults in 95.9%, the dry mass consumed in 88.3%, and increased the Z. subfasciatus life cycle in 40.3% compared to susceptible genotypes (IAC Alvorada and 178). Crude protein content in the resistant genotypes was on average 10.9% higher than in the susceptible genotypes. Some proteins, such as arcelin, have antibiotic effects on bruchid beetles, indicating that a higher protein content in resistant genotypes may have been one of the mechanisms responsible for antibiosis of these genotypes to Z. subfasciatus.

Gene Sequences of Potential Targets of Insecticidal PF2 Lectin Identified from the Larval De Novo Transcriptome of the Mexican Bean Weevil (Zabrotes Subfasciatus; Boheman 1833).

Simple SummaryThe Mexican bean weevil Zabrotes subfasciatus is a major insect pest of stored beans. We have previously reported that the PF2 lectin, which is a protein found in the desert wild legume Olneya tesota (Palo Fierro), is toxic to Z. subfasciatus by inhibiting its early larval development. The use of proteomic means allowed us to identify PF2 targets in the midgut of Z. subfasciatus larvae. However, efforts to completely elucidate the insecticidal mechanism of PF2, as well as novel potential targets for insecticidal compounds, have been hindered by the lack of available genomic and proteomic information of non-model insects. Therefore, in this work we massively sequenced and analyzed the transcripts expressed in the larval stage of Z. subfasciatus, which is the first transcriptome reported for this insect. A total of 29,029 transcript sequences were identified, of which 30 sequences encode putative targets of PF2. The functional characteristics and biochemical, biological, or molecular roles for 15,124 sequences were established by means of bioinformatics tools. This study significantly increased the available genetic resources for Zabrotes and related insect species and will be helpful for any kind of future study that requires information on genes or protein sequences.The available genomic and proteomic information of non-model organisms is often underrepresented in public databases hindering their study at molecular, cellular, and physiological levels. Information on Zabrotes subfasciatus (Mexican bean weevil) is poorly represented in databases, yet it is a major pest of common beans. We report the transcriptome of Z. subfasciatus larvae; transcripts were sequenced using an Illumina RNA-Seq technology and assembled de novo identifying 29,029 unigenes with an average size of 1168 bp and an N50 value of 2196 bp. About 15,124 unigenes (52%) were functionally annotated and categorized. Further analysis revealed 30 unigene sequences encoding putative targets of the insecticidal PF2 lectin. The complete deduced amino acid sequences of eight selected proteins potentially related to insecticidal mechanism of Palo Fierro 2 (PF2) were used for predicting probable N-glycosylation sites and analyzing phylogenetic relationships with insect sequences. This work provides a dramatic increase in the genetic resources available for Coleopterans and set the basis for developing future studies on biological aspects and potential control strategies for Z. subfasciatus.

Multigenerational experimental simulation of climate change on an economically important insect pest.

Long‐term multigenerational experimental simulations of climate change on insect pests of economically and socially important crops are crucial to anticipate challenges for feeding humanity in the not‐so‐far future. Mexican bean weevil Zabrotes subfasciatus, is a worldwide pest that attacks the common bean Phaseolus vulgaris seeds, in crops and storage. We designed a long term (i.e., over 10 generations), experimental simulation of climate change by increasing temperature and CO2 air concentration in controlled conditions according to model predictions for 2100. Higher temperature and CO2 concentrations favored pest's egg‐to‐adult development survival, even at high female fecundity. It also induced a reduction of fat storage and increase of protein content but did not alter body size. After 10 generations of simulation, genetic adaptation was detected for total lipid content only, however, other traits showed signs of such process. Future experimental designs and methods similar to ours, are key for studying long‐term effects of climate change through multigenerational experimental designs.

Seed Predation on Oil-Polluted and Unpolluted Vachellia (Acacia) Trees in a Hyper-Arid Desert Ecosystem.

Simple SummaryBruchid beetles are the pests of many plant species worldwide. One or more grubs can develop inside a seed by consuming it and impairing its germination. Vachellia trees are important for preserving diverse and healthy arid ecosystems, but they are often threatened by human activities and hostile environmental conditions. Seed predation by bruchid beetles is one of the major causes of the decline in the populations of Vachellia trees in Israel. In a hyper-arid desert ecosystem affected by two major oil spills (in 1975 and 2014), we evaluated whether oil pollution increases seed predation rates of the seeds of Vachellia tortilis and V. raddiana. We recorded remarkably high predation rates for both species, particularly at the ground level, which suggests that conservation measures to reduce repeated infestations on fallen pods may be important to preserve these tree species. However, we found no clear evidence of a negative effect of oil pollution on seed predation, indicating that it did not increase the vulnerability of the seeds to bruchids even in trees affected by the recent oil spill.Acacia trees are keystone species in many arid environments, supporting high levels of plant and animal diversity. In Israel, the populations of Vachellia (formerly Acacia) tortilis (Forssk.) and V. raddiana (Savi) are declining at an alarming rate. Severe infestations by bruchid beetles (Coleoptera, Chrysomelidae) are among the major causes of seed mortality, but additional environmental stressors can reduce the defence level of the seeds, exacerbating their susceptibility to predators. In a hyper-arid desert ecosystem affected by two major oil spills (in 1975 and 2014), we quantified seed predation rates caused by insect granivores before and after the pods dropped to the ground. We recorded predation rates of up to 84% for both tree species, and higher predation rates at the ground level than in the canopy, suggesting that repeated infestations occur. These results reinforce the call to protect the populations of large ungulates such as gazelles, which kill the bruchids by feeding upon the pods, and promote seed germination and dispersion. We found no clear evidence of a negative effect of the oil spill on seed predation, indicating that oil pollution did not increase the vulnerability of the seeds to granivores even in trees affected by the recent oil spill.

BIOACTIVITY OF EXTRACTS FROM SOLANACEAE AGAINST Zabrotes subfasciatus

The botanical family Solanaceae has many species producing compounds with insecticidal properties, e.g. nicotine and capsaicin, which are used for pest management in agriculture. This fact provides perspectives to identify insecticidal compounds in Brazilian native species of Solanaceae. In this study, we performed a screening with 25 ethanolic extracts from 17 Solanaceae species in order to evaluate their bioactivity against the Mexican bean weevil, Zabrotes subfasciatus(Coleoptera: Chrysomelidae: Bruchinae). The bioactivity of Solanaceae ethanolic extracts (2500 mg kg-1) was tested with residual contact bioassays. Adults ofZ. subfasciatus were exposed to treated bean grains, and adult mortality, oviposition, F1progeny and damages on grains were quantified. Most of the ethanolic extracts from Solanaceae reduced the number of eggs per sample, the egg-adult viability, the F1progeny and the damages on bean grains promoted byZ. subfasciatus, but none of them interfered on its sex ratio. Ethanolic extract from leaves of Solanum lycocarpumA. St.-Hil promoted the most promissory effects on Z. subfasciatus. This ethanolic extracts can be a suitable alternative to control Z. subfasciatus in stored beans, mainly for small farmers and organic farmers.

Toxic, Oviposition Deterrent and Oxidative Stress Effects of Thymus vulgaris Essential Oil against Acanthoscelides obtectus.

Simple SummaryCompounds of botanical origin, including essential oils (EOs), which coevolved as plant defense mechanism against herbivores and pathogens have been proposed as a promising strategy for post-harvest control of stored product insects. Despite several drawbacks, such as low stability, phytotoxicity and food odor changes at high concentrations, EOs are believed to be safe for human and environmental health and thus have an advantage comparing to conventional insecticides. The present study was aimed to examine acute toxicity and effects of thyme (Thymus vulgaris) EO on longevity, behavior and physiology of the bean weevil (Acanthoscelides obtectus), a major pest of stored bean seeds. We found that exposure to thyme oil reduced adult survival and longevity and induced damages to lipids and proteins in a concentration-dependent manner. Sublethal EO concentrations also deterred female egg laying and strongly inhibited adult emergence. Efficacy of such low EO concentrations in suppression of adult emergence implies that thyme EO might be cost-effective and environmentally low risk botanical insecticide for bean seed protection against A. obtectus.The bean weevil Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae: Bruchinae) can cause significant losses in production of its primary host common bean Phaseolus vulgaris L. To avoid bean protection with environmentally risky chemical insecticides and provide sustainable and safe production of food, new pest management methods based on natural compounds are investigated. In the present study, we evaluated protective potential of the essential oil (EO) from the common thyme Thymus vulgaris L. applied on bean seeds. We assessed residual contact toxicity of thyme EO and its effects on A. obtectus longevity, oviposition and adult emergence. Furthermore, to elucidate the role of oxidative stress in thyme EO toxicity, we estimated the levels of oxidatively damaged proteins and lipids, as well as the level of thiols which have important role for antioxidant capacity. We found that thyme oil significantly reduced adult survival and longevity, induced oxidative damage to lipids and proteins and depleted protein and non-protein thiols in a concentration-dependent manner. Females appeared to be more tolerant to thyme oil treatment than males. Sublethal EO concentrations affected oxidative stress indices, deterred oviposition and strongly inhibited adult emergence. The results suggest that thyme oil has the potential to be used as an ecofriendly insecticide for A. obtectus control.

Inheritance and metabolomics of the resistance of two F2 populations of Phaseolus spp. to Acanthoscelides obtectus

The bean weevil Acanthoscelides obtectus is one of the major storage pests of dry bean. Tepary bean (Phaseolus acutifolius) is a great source of resistance against A. obtectus to improve dry bean production. We developed two F2 populations of Phaseolus spp. by crossing bean genotypes resistant to A. obtectus × susceptible, to (1) search for metabolites related to bean weevil resistance using an untargeted metabolomics approach and (2) understand the genetics of resistance to A. obtectus attack using the number of adults emerged from seeds as resistance criteria. The segregation of the number of adults emerged from seeds showed that the genetics of resistance (0 emerged adults = resistant, 1 or more emerged adults = susceptible) was controlled by a single dominant gene in two (resistant × susceptible) F2 populations. From nine metabolites detected, pipecolic acid concentration was significantly higher in the testa of resistant individuals than in the testa of susceptible individuals. From a breeding point of view, (P. Saltillo × T. amarillo) F2 is of special interest because it is derived from a cultivated tepary × cultivated common bean cross and showed 3:1 resistant vs susceptible segregation. Therefore, this F2 is a suitable base material for breeding programmes to obtain new bean lines with good agronomic performance, seed quality and resistance to insect attack. Pipecolic acid plays a role in resistance against A. obtectus.

Population Development of Bean Weevils (Coleoptera: Chrysomelidae: Bruchinae) in Landrace Varieties of Cowpeas and Common Beans

Bean weevils (Coleoptera: Chrysomelidae: Bruchinae) are responsible for large quantity losses of cowpea (Vigna unguiculata (L.) Walp.; Fabaceae) and common bean (Phaseolus vulgaris L.; Fabaceae). The magnitude of damage is related to the grains’ varietal susceptibility. The objective of this study was to determine the population development rates of Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) in 4 landrace varieties of cowpea (var. ‘UFAC-B01,’ ‘UFAC-MV01,’ ‘UFAC-MG01,’ and ‘UFAC-Q01’), as well as the population development rates of Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae) in 4 landrace varieties of common bean (var. ‘UFAC-G01,’ ‘UFAC-M01,’ ‘UFAC-P01,’ and ‘UFAC-R01’). We determined the population development rates of the weevils in each variety. The weight of 100 grains (g) and the percentage of grain weight loss were measured, and correlations between these variables were analyzed. The statistical design was completely randomized, with 4 replications. Varieties UFAC-Q01 (cowpea) and UFAC-R01 (common bean) showed lower insect population development rates than other varieties. Although variations were found in the weight of 100 grains and grain weight loss, no significant correlations with bean weevil population development were observed. The cowpea and common bean landrace varieties from the southwestern Amazon region are important sources of resistance to bean weevils. The UFAC-Q01 cowpea variety and the UFAC-R01 common bean variety showed lower susceptibility to C. maculatus and Z. subfasciatus, respectively. Resumo Os bruquideos (Coleoptera: Chrysomelidae: Bruchinae) sao responsaveis por elevadas perdas na qualidade do caupi (Vigna unguiculata (L.) Walp.; Fabaceae) e feijao comum (Phaseolus vulgaris L.; Fabaceae), sendo que a magnitude dos danos esta relacionados a susceptibilidade varietal dos graos. O objetivo desta investigacao foi determinar as taxas de desenvolvimento populacional de Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) em quarto variedades crioulas de caupi (var. ‘UFAC-B01,’ ‘UFAC-MV01,’ ‘UFAC-MG01,’ e ‘UFAC-Q01’), bem como a a taxa de desenvolvimento populacional de Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae) em quarto variedades crioulas de feijao comum (vbean weevilsar. ‘UFAC-G01,’ ‘UFAC-M01,’ ‘UFAC-P01,’ e ‘UFAC-R01’). Foram realizados bioensaios para determinar as taxas de desenvolvimento populacional dos bruquideos em cada variedade, e avaliou-se a massa de 100 graos (g), perda de massa (%) e foram realizadas analises de correlacao entre estes fatores. O delineamento estatistico foi inteiramente casualizado com quatro repeticoes. As variedades UFAC-Q01 e UFAC-R01 de caupi e feijao comum, respectivamente, apresentaram menores taxas de desenvolvimento populacional, comparando-se com as demais variedades. Embora tenha havido variacao da massa de 100 graos, perda de massa, nao foram constadas correlacoes significativamente com o desenvolvimento populacional dos bruquideos. As variedades landraces de caupi e feijao comum, oriundos da Amazonia Sul-Ocideltal, constituem importantes fontes de resistencia para bruquideos, sendo que as variedades UFAC-Q01 e UFAC-R01 de caupi e feijao comum apresentaram menor susceptibilidade ao ataque de C. maculatus e Z. subfasciatus. Key Words: Vigna unguiculata; Phaseolus vulgaris; varietal susceptibility; storage; bruchids View this article in BioOne

Genetic diversity analysis of common bean (Phaseolus vulgaris L.) genotypes for resistance to Mexican bean weevil (Zabrotes subfasciatus), using single nucleotide polymorphism and phenotypic markers

ABSTRACT The objective of this study was to examine the genetic diversity present among 297 common bean genotypes using 2554 SNPs and 12 insects and seed-related traits. The phenotyping was done under laboratory condition while the genotyping was conducted by using the Illumina SNP BeadChip. High phenotypic diversity among traits were recorded, ranging from 0.87 to 0.96, with a mean of 0.92. Principal component and discriminant analyses identified four PCs and three discriminant functions, which explained 82% and 100% of the total phenotypic variations among genotypes, respectively. Polymorphic Information Content ranged from 0.21 to 0.38, with a mean of 0.34. The mean gene diversity among genotypes ranged from 0.24 to 0.50, with a mean of 0.44. Genetic distance ranged from 0.19 to 0.82, with a mean of 0.62, while the phenotypic distance ranged from 0.00 to 1.00, with a mean of 0.64 were observed aamong genotypes. The analysis of molecular variance revealed highly significant differences (p<0.001) among and within individuals and among populations. Both the SNP and the phenotypic markers grouped the 297 genotypes into two major distinct clusters and three sub-clusters. This information is useful for identification and development of common bean germplasm with economically valuable traits and the conservation and utilization of genotypes.

Colonization of Marginal Host Plants by Seed Beetles (Coleoptera: Chrysomelidae): Effects of Geographic Source and Genetic Admixture

The ability to adapt to a novel host plant may vary among insect populations with different genetic histories, and colonization of a marginal host may be facilitated by genetic admixture of disparate populations. We assembled populations of the seed beetle, Callosobruchus maculatus (F.), from four continents, and compared their ability to infest two hosts, lentil and pea. We also formed two cross-continent hybrids (Africa × N.A. and Africa × S.A.). In pre-selection assays, survival was only ~3% in lentil and ~40% in pea. For three replicate populations per line, colonization success on lentil was measured as cumulative exit holes after 75-175 d. On pea, we estimated the change in larval survival after five generations of selection. Females in all lines laid few eggs on lentil, and survival of F1 larvae was uniformly <5%. Subsequently, however, the lines diverged considerably in population growth. Performance on lentil was highest in the Africa × N.A. hybrid, which produced far more adults (mean > 11,000) than either parental line. At the other extreme, Asian populations on lentil appeared to have gone extinct. The Africa × N.A. line also exhibited the highest survival on pea, and again performed better than either parent line. However, no line displayed a rapid increase in survival on pea, as is sometimes observed on lentil. Our results demonstrate that geographic populations can vary substantially in their responses to the same novel resource. In addition, genetic admixtures (potentially caused by long-distance transport of infested seeds) may facilitate colonization of an initially poor host.

Expanding the European distribution limits of &lt;em&gt;Bruchidius raddianae&lt;/em&gt;. First record in Portugal from Vachellia karroo’s infested seeds (Coleoptera: Bruchidae; Fabales: Fabaceae)

Several Australian and African Acacia shrubs and trees have been intentionally introduced into the Mediterranean basin for different purposes, but some species become invasive, such as Vachellia karroo (Hayne) Banfi and Galasso (syn. Acacia karroo) (Fabales: Fabaceae). The seed beetles, belonging to family Bruchidae, have a significant ecological and economic importance, either because they can be plant pests or, on the other hand, be used as biocontrol agents against invasive plant species. Bruchidius raddianae (Anton and Delobel, 2003) (Coleoptera: Bruchidae) is native to tropical and subtropical areas, but it has been recently reported from Cádiz and Málaga (southern Spain, 2007) and in the Lampedusa Island (Italy, 2015) from seeds of pods collected from V. karroo. This paper reports 104 specimens reared from seeds collected from V. karroo in Faro (southern Portugal) from August to October 2019, expanding the B. raddianae’ European distribution limits. This is also the first report of its presence in Portugal and the third in Europe.

Fecundity and fertility inhibition effects of some plant essential oils and their major components against Acanthoscelides obtectus Say (Coleoptera: Bruchidae)

Fecundity (egg production) and fertility (egg hatchability/progeny production) are important components of both sexual and asexual reproduction of insects. Some plant essential oils (EOs) are reported to be active inhibitors against various insect pests by reducing or completely hindering their fecundity and fertility. The present study was carried out to determine the inhibitory effects of three plant EOs [eucalyptus (Eucalyptus camaldulensis Dehn.), peppermint (Mentha piperita L.) and anise (Pimpinella anisum L.)] and their major components (1,8-cineole, L-menthol and trans-anethole, respectively) on egg-laying and progeny production of bean weevil, Acanthoscelides obtectus Say (Coleoptera: Bruchidae), which is an economically important pest of common bean, Phaseolus vulgaris L. (Fabaceae), in tropical and subtropical regions. The EOs were extracted by hydro-distillation, and their chemical composition was determined by gas chromatography–mass spectrometry. The oils and components were bio-assayed via fumigation against the pest by exposing newly emerged virgin females and young males to the median lethal concentration (LC50) of each material for 10 h. After the exposure, the surviving individuals were mated in the following combinations; treated females × treated males (TF × TM), untreated females × treated males (UF × TM), treated females × untreated males (TF × UM), untreated females × untreated males (UF × UM). According to the results, the highest fecundity inhibition was observed in TF × TM with 86.05%, 71.9% and 55.72% for anise, eucalyptus and peppermint oils, respectively. In addition, the highest progeny production inhibition was seen in the TF × TM combination with 93.3%, 68.0% and 44.9% after exposing to eucalyptus, anise and peppermint oils, respectively. Overall the results showed that the exposure of newly emerged adults by the median lethal concentration of EOs and their major components negatively affected the egg-laying and progeny production of bean weevil. These results may also pioneer new approaches in insect pest control of stored products.

Insecticidal effects of some essential oils against Tribolium confusum (du Val.) and Acanthoscelides obtectus (Say), (Coleoptera: Tenebrionidae and Bruchidae) adults

In this study, insecticidal effects of the essential oils obtained from plants Ocimum basilicum L., Rosmarinus officinalis L. and Artemisia dracunculus L. on confused flour beetle (Tribolium confusum du Val., 1863 (Coleoptera: Tenebrionidae)) and bean weevil (Acanthoscelides obtectus (Say), 1831 (Coleoptera: Bruchidae)) adults were tested in laboratory conditions. In this context, T. confusum and A. obtectus adults were exposed to essential oils at 10 and 20 μL/petri doses for 24, 48, 72 and 96 h. All of the essential oils used in the study caused mortalities at different rates in two application doses but end of the 96 h all mortality rates were obtained similar (O. basilicum 98.3%, R. officinalis 98.3%, A. dracunculus 93.3% against T. confusum adults; O. basilicum 100%, R. officinalis 100%, A. dracunculus 100% against A. obtectus adults). It was determined that the effects of essential oils on A. obtectus adults were greater than T. confusum adults. Especially when the dosage was 20 μL, the death rate increased up to over 95% after 96 h for all types. The mortality rates increased with increasing exposure period at the 48, 72 and 96 h. in all applications. The results of the study suggest that essential oils from O.basilicum and R.officinalis could have a potential as control agents against A. obtectus and T.confusum adults under storage conditions.

Food quality effects on instar-specific life histories of a holometabolous insect.

It is a long‐standing challenge to understand how changes in food resources impact consumer life history traits and, in turn, impact how organisms interact with their environment. To characterize food quality effects on life history, most studies follow organisms throughout their life cycle and quantify major life events, such as age at maturity or fecundity. From these studies, we know that food quality generally impacts body size, juvenile development, and life span. Importantly, throughout juvenile development, many organisms develop through several stages of growth that can have different interactions with their environment. For example, some parasitoids typically attack larger instars, whereas larval insect predators typically attack smaller instars. Interestingly, most studies lump all juvenile stages together, which ignores these ecological changes over juvenile development.We combine a cross‐sectional experimental approach with a stage‐structured population model to estimate instar‐specific vital rates in the bean weevil, Callosobruchus maculatus across a food quality gradient. We characterize food quality effects on the bean weevil's life history traits throughout its juvenile ontogeny to test how food quality impacts instar‐specific vital rates.Vital rates differed across food quality treatments within each instar; however, their effect differed with instar. Weevils consuming low‐quality food spent 38%, 37%, and 18% more time, and were 34%, 53%, and 63% smaller than weevils consuming high‐quality food in the second, third, and fourth instars, respectively. Overall, our results show that consuming poor food quality means slower growth, but that food quality effects on vital rates, growth and development are not equal across instars. Differences in life history traits over juvenile ontogeny in response to food quality may impact how organisms interact with their environment, including how susceptible they are to predation, parasitism, and their competitive ability.

Assessment of Grain Storage Structures and Containers in Relation to Build-Up of Insect and Rodent Pests in Southwestern Ethiopia

This study was designed to assess farmers grain storage containers in relation to buildup of storage pests in three selected districts of southwestern Ethiopia. One district was selected from each zone based on the production potential of selected grain crops such as maize, sorghum, wheat and faba bean. Then, 25 households were randomly selected from each district to collect stored grain samples used for the identification of storage insect pests, and grain samples were taken from different storage structures, including un-plastered and plastered gombisa, gumbi, and polypropylene sacks. The results showed that the dominant insect species in maize, sorghum and wheat grains were weevils ( Sitophilus spp.) followed by the Angoumois grain moth ( Sitotroga cerealella Olivier) and flour beetles ( Tribolium spp.), while the bean weevil ( Zabrotes spp.) was the only species recovered from stored faba beans. High numbers of insects were recorded from both plastered and un-plastered gombisa, gumbi and polypropylene sacks. In addition, the number of each insect pest in each storage method recorded per 100 g -1 grain increased as the duration of grain storage increased. The results of this study also demonstrated that most of the farmers in the study areas perceived insect pests and rodents as the main postharvest pests causing considerable losses of stored grains. The poor storage systems of farmers predispose the stored grains to insect and rodent attacks. Thus, there is a need to train farmers on storage hygiene and to develop and disseminate efficient grain storage facilities to reduce losses in grain stores. Moreover, further studies need an improved pest detection method, such as the use of bioacoustics tools, to manage pests associated with grain stores. Keywords: grain, insects, rodents, storage DOI : 10.7176/FSQM/93-04 Publication date: January 31 st 2020