Bruchidae Research Articles

Changes in the insecticide susceptibility and physiological trade-offs associated with a host change in the bean weevil Acanthoscelides obtectus

For most of the seed weevils (Coleoptera: Chrysomelidae: Bruchinae), the ability to survive environmental stresses like insecticide exposure and reproduction is variable and depends on the host. Here, we evaluated the physiological costs and benefits of a host shift from kidney beans of the landrace “Vermelho” to cranberry beans of the landrace “Manteigao” in the bean weevil Acanthoscelides obtectus. We assessed the susceptibility of A. obtectus to the commercial pyrethroid deltamethrin and clove and cinnamon essential oils as potential alternative insecticides and measured its reproductive performance (e.g., oviposition and emergence rates) on both hosts. The females of A. obtectus reared on kidney beans were less susceptible to both deltamethrin and clove essential oil and showed more sources of energy in the trophocytes although the attraction of adult females to both hosts was similar. However, the females reared on cranberry beans had higher reproductive performances and respiration rates, indicating that more energy was expended on reproduction than on the mitigation of the insecticide actions. Thus, with a change in hosts, a trade-off between reproductive fitness and the susceptibility to insecticides was demonstrated for A. obtectus. These results should not only affect the management of A. obtectus in storage units but also the understanding of these insects’ host adaptativeness.

Toxicity of an Annonin-Based Commercial Bioinsecticide Against Three Primary Pest Species of Stored Products.

The effects of a bioinsecticide formulation based on extract of Annona squamosa L. (Annonaceae) containing 10,000mgL-1 of acetogenin annonin as the main active ingredient were investigated against three primary pest species of stored grains in Brazil [maize weevil Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), Mexican bean weevil Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae: Bruchinae), and cowpea weevil Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae: Bruchinae)] by means of residual contact bioassays. In a concentration-dependent manner, the annonin-based commercial bioinsecticide caused significant adult mortality of C. maculatus (LC50=6890μLkg-1), S. zeamais (LC50=2781μLkg-1), and Z. subfasciatus (LC50=2120μLkg-1) after 120h of residual contact exposure. In addition to acute toxicity, the tested bioinsecticide also promoted a significant reduction of the number of eggs laid by females of C. maculatus (EC50=5949.7μLkg-1) and Z. subfasciatus (EC50=552.7μLkg-1). Moreover, the bioinsecticide significantly reduced the number of emerged insects (F1 generation) of C. maculatus (EC50=2763.0μLkg-1), S. zeamais (EC50=1380.8μLkg-1), and Z. subfasciatus (EC50=561.5μLkg-1). The bioinsecticide also reduced the percentage of damaged grains for the three pest species studied, and its grain-protectant properties are comparable to or superior in efficacy in relation to a diatomaceous earth-based insecticide (Insecto® at 1000mgkg-1) used as a positive control. Thus, this standardized formulation has promising bioactivity against stored insect species and can be a useful component for IPM of stored grains in Brazil and elsewhere.

Protective effects of three Artemisia essential oils against Callosobruchus maculatus and Bruchus rufimanus (Coleoptera: Chrysomelidae) and the extended side-effects on their natural enemies

This research aimed to find plant essential oils with a strong fumigant-specific toxicity effects against Callosobruchus maculatus and Bruchus rufimanus, but which have lower side effects on their parasitoids wasps Dinarmus basalis and Triaspis luteipes. For that, the essential oils of Artemisia herba-alba, A. campestris and A. absinthium were investigated for their chemical composition using GC and GC–MS analysis and were used in a manner that combined exposure to their essential oils with parasitoids releases. Essential oils were assessed for their direct fumigant toxicity against both bruchid beetles and for their residual effects on parasitism rates and pests offspring control. The introduction of D. basalis and T. luteipes adults were done 6 days after the oil application.The results showed that A. campestris essential oil can be considered compatible with the natural enemies for controlling stored food legume beetles. When the parasitoids D. basalis and T. luteipes were released six days after the application of A. campestris oil, the parasitism rates reached 13.6% and 80.3% for C. maculatus and B. rufimanus respectively. Moreover, 26.6% of C. maculatus offspring have emerged, while for B. rufimanus a complete lack of offspring was recorded. Adults of D. basalis were more susceptible to oils vapours than adults of T. luteipes.The release of parasitoids could better be combined with essential oils of A. campestris, as this oil had more pronounced effects on the beetles than on their parasitoids, in particular for the case of B. rufimanus and T. luteipes.

Penghambatan aktivitas peneluran kumbang kacang hijau Callosobruchus Chinensis L. (Coleoptera: Bruchidae) oleh extrak sepuluh spesies tumbuhan

Oviposition Deterrence of Bean Weevil, Callosobruchus chinensis L.(Coleoptera: Bruchidae) Treated with Ten Plant Extracts. Pest and Diseases attack agricultural products not only in the field but also in storehouse. Their attack causes decreasing both quantity and quality of stored materials. One of important stored product insect pests is Callosobruchus chinensis L. (Coleoptera: Bruchidae). Till now the effective strategy to control this insect pest is chemical control by using synthetic insecticides. The improper use synthetic insecticides causes some undesirable effects, so alternative strategist should be searched to controls insect pests in storehouse. One of the alternatives is by using plant materials as insect pests control agent. The aim of this study was to find out the oviposition deterrence of C. chinensis treated with ten plant which were extracted with methanol, hexane and ether. Oviposition deterrence was evaluated by choice and no-choice methods at 1,3 and 5% of extract concentration. Extract of Acorus calamus (methanol), A.calamus (hexane), A. calamus (ether), Illicium verum (ether), Pogostemon calbin (hexane), P. cablin (ether), Vetiveria zizanioides (hexane), and V. zizanioides (ether) were able to deter ovipostion activity of C. chinensis by more than 90% of deterrence. Further study should be conducted to isolate and identify the active compound and to make botanical insecticide formulation for practical use as a commercial product.

Ability of a Generalist Seed Beetle to Colonize an Exotic Host: Effects of Host Plant Origin and Oviposition Host.

The colonization of an exotic species by native herbivores is more likely to occur if that herbivore is a generalist. There is little information on the life-history mechanisms used by native generalist insects to colonize exotic hosts and how these mechanisms are affected by host properties. We examined the ability of the generalist seed beetle Stator limbatus Horn to colonize an exotic species. We compared its host preference, acceptability, performance, and egg size when ovipositing and developing on two native (Pithecellobium dulce (Roxb.) Benth and Senegalia riparia (Kunth)) and one exotic legume species (Leucaena leucocephala (Lam.)). We also analyzed the seed chemistry. We found that females recognize the exotic species as an unfavorable host for larval development and that they delayed oviposition and laid fewer and larger eggs on the exotic species than on the native species. Survivorship on the exotic host was 0%. Additionally, seeds of the native species contain five chemical compounds that are absent in the exotic species, and the exotic species contains three sterols, which are absent in the native legumes. Genetically based differences between beetles adapted to different hosts, plastic responses toward new hosts, and chemical differences among seeds are important in host colonization and recognition of the exotic host. In conclusion, the generalist nature of S. limbatus does not influence its ability to colonize L. leucocephala. Explanations for the colonization of exotic hosts by generalist native species and for the success of invasive species must be complemented with studies measuring local adaptation and plasticity.

Attraction of Coffee Bean Weevil, Araecerus fasciculatus, to Volatiles from the Industrial Yeast Kluyveromyces lactis.

The coffee bean weevil (CBW), Araecerus fasciculatus (De Geer, 1775) (Coleoptera: Anthribidae) is an important pest of stored products such as grains, coffee beans, cassava, and traditional Chinese medicine materials. In China, CBW causes large losses of Daqu, a traditional Chinese liquor fermentation starter, and, unfortunately, the use of conventional insecticides against CBW is not suitable in Daqu storage. We found CBW to be highly attracted to fermenting yeast cultures, such as Kluyveromyces lactis. Eight volatile compounds, produced by fermenting cultures and not by sterile samples, were identified by gas chromatography coupled with mass spectrometry. Five of these substances elicited significant responses in Y-tube behavioral bioassays. Field trapping experiments revealed 2-phenylethanol and 2-phenylethyl acetate to be crucial for attraction of CBW. Results show that yeast volatiles play an important role in host location, and that 2-phenylethanol and 2-phenylethyl acetate could be utilized as potential attractants in monitoring and control systems against this important pest.

Toxicity and metabolic mechanisms underlying the insecticidal activity of parsley essential oil on bean weevil, Callosobruchus maculatus

Control of the bean weevil, Callosobruchus maculatus (Coleoptera: Chrysomelidae: Bruchinae), in stored cowpea beans, Vigna unguiculata (L) Walp., when accomplished, is mainly achieved by applications of phosphine. However, the long-term use of this insect control practice has contributed to the selection of resistant populations, enhancing the need to develop alternative control tools. Due to their diverse biologically active compounds, the essential oils of aromatic plants such as parsley, Petroselinum sativum L., have been suggested as suitable alternatives for controlling insect pests. Here, we evaluated the toxicity (including the metabolic mechanisms underlying the insecticidal activity) of parsley essential oil against C. maculatus. Parsley essential oil controlled C. maculatus in a concentration-dependent manner (concentration increases resulted in lower weight losses and better germination levels of beans) with a fumigant toxicity (LC50: 489.5 μL L−1 air) significantly lower than that observed for phosphine (LC50: 35.7 μL L−1 air). However, when applied at their LC10 values (Parsley essential oil: 399.3 μL L−1 air. Phosphine: 18.6 μL L−1 air), the parsley essential oil caused significantly higher reductions in the emergence of C. maculatus compared with phosphine. Additionally, application of the synergists piperonyl butoxide (PBO), triphenyl phosphate (TPP) and diethyl maleate (DEM) demonstrated that glutathione S-transferases enhanced the parsley essential oil toxicity, while cytochrome P450-dependent monooxygenases formed part of the resistance mechanisms used by C. maculatus to mitigate the toxicity of the essential oil. Our findings suggest that parsley essential oil may be integrated into the control of C. maculatus only when synergized with PBO.

Pharmacognostic standardization and insecticidal activity of the leaves of <i>Hyptis suaveolens</i> (L.) Poit (Lamiaceae)

Lamiaceae have traditionally been used in developing countries for their insecticidal and repellant properties against several insect species. Hyptis suaveolens has been reported to repel mosquitoes and other insects effectively when burnt overnight in rooms. This study was aimed at establishing the Pharmacognostic profile and insecticidal/repellant activity of the leaves of H. suaveolens (L.) Poit against maize/bean weevils. Evaluation of the fresh, powdered and anatomical sections of the leaves was carried out to determine the macromorphological, micromorphological, chemomicroscopic, numerical and phytochemical profile. Evaluation of the insecticidal activity involved the determination of antifeedant properties, repellant and insecticidal actions of the extract and its fractions against adult Sitophilus zeamais (maize weevil) and Acanthscelides obtectus (bean weevil). Macro and microscopic studies gave results that could serve as a basis for proper identification, collection and investigation of the leaves of H. suaveolens . Phytochemical screening revealed the presence of alkaloids, tannins, saponins and cardiac glycosides. The crude extract and fractions produced antifeedant, repellant and insecticidal activities to varying degrees against Adult Sitophilus zeamais (maize weevil) and Acanthscelides obtectus (bean weevil). H. suaveolens has the potential to act as a lead in the commercial production of insecticides of plant origin. This will go a long way in ameliorating the deleterious effects associated with synthetic chemicals. Keywords: H. suaveolens ; Pharmacognostic profile; Insecticidal activity; Phytochemical constituents; Weevils

Genetic diversity and differentiation ofAcanthoscelides obtectusSay (Coleoptera: Bruchidae) populations in China

Bean weevil Acanthoscelides obtectus Say is one of the most destructive pests of bean seeds. Using 10 microsatellite loci, we studied the genetic diversity and differentiation of 13 geographical populations. A total of 79 alleles were detected, with an average of 7.900 alleles per locus. The gene flow and genetic differentiation rate values at the 10 loci varied from 0.376 to 1.560 and 13.8–39.9%, with averages of 0.774% and 24.4%, respectively. Among the 13 populations, the effective number of alleles and observed heterozygosity ranged from 1.865 to 2.848 and 0.457 to 0.646, respectively. Shannon's information index ranged from 0.684 to 1.104. In all comparisons, the fixation index (FST) values ranged from 0.021 to 0.463, with a total FST value of 0.228 among the 13 populations, indicating a moderate level of genetic differentiation among these populations. Analysis of molecular variance revealed that the genetic variation within populations accounted for 67.7% of the total genetic variation. Using the unweighted pair group method with arithmetic mean cluster analysis, 13 populations were clustered into three distinct genetic groups. The pattern of the three concentrated groups from principal component analysis showed a similar result to cluster, although some individuals interpenetrated with one another.

English

Bean crop occupies a prominent place in medium and large farming units in Brazil. Most of the time, the success of this crop depends, among other factors, on the use of good quality seeds at sowing; which requires strict quality control, harvesting, and storage. The objective of this study is to evaluate the effect of leaves and shells extracts of Aspidosperma pyrifolium Mart., Anadenanthera colubrina and myrtle (Licania rigida benth) in controlling Zabrotes subfasciatus associated with bean seeds and to evaluate the seeds treated and stored in pet bottles for a period of 180 days. The experiments were conducted in the Agricultural Products Storage and Processing laboratory of the Federal University of Campina Grande. It was observed that for leave extracts, germination decreased with storage time for all the extracts and the best germination percentage (95.00%) occurred in 5 ml of A. pyrifolium Mart. leaves extract. These results found for the bark extract A. pyrifolium Mart. showed that germination was 94.00% in the seeds treated with 5 ml dose of this extract. On the other hand, the extracts that had lower efficiency on germination were the extract of myrtle leaf and bark which showed 64.00 to 65.40% germination in 180 days of storage. It is concluded that low percentages of infestation show the efficiency of the extracts tested in the control of insects. The efficiency of these extracts may be due to the action of their secondary metabolites; especially the extracts of A. colubrina’s leaves and bark. Key words: Bioactive plants, bean weevil, stored seeds.

Antennal and mouthpart sensilla of Acanthoscelides obtectus say (Coleoptera: Bruchidae).

Acanthoscelides obtectus, a serious pest with a worldwide distribution, damages stored seeds of Phaseolus sp. To acquire a better understanding of the sensory orientation of bean weevils, their antennal and palpal sensilla were investigated. The antennae and palps possess several types of sensory hairs: blunt-tipped sensilla chaetica and trichoidea and also sharp-tipped sensilla trichoidea, these last being the most numerous. Sensilla basiconica are present only on the flagellomeres, but Böhm bristles occur on the basal sclerite and scape of the antennae. The terminal segments of the maxillary and labial palps bear a group of sensilla styloconica with single apical pores. Sensilla coeloconica are located only on the terminal palpal segments. They were unable to detect any distinct morphological differences between males and females. The possible chemosensory, mechanosensory, and thermo-/hygroreceptive functions of the sensilla are discussed.

Construction of an integrated map and location of a bruchid resistance gene in mung bean

Bruchid beetle (Callosobruchus chinensis) poses a serious threat to the production and storage of mung bean (Vigna radiata). Mapping bruchid resistance (Br) will provide an important basis for cloning the responsible gene(s) and elucidating its functional mechanism, and will also facilitate marker-assisted selection in mung bean breeding. Here, we report the construction of the genetic linkage groups of mung bean and mapping of the Br1 locus using an RIL population derived from a cross between Berken, a bruchid-susceptible line, and ACC41, a bruchid-resistant line. A total of 560 markers were mapped onto 11 linkage groups, with 38.0% of the markers showing distorted segregation. The lengths of the linkage groups ranged from 45.2 to 117.0cM with a total coverage of 732.9cM and an average interval of 1.3cM between loci. Br1 was located on LG9 between BM202 (0.7cM) and Vr2-627 (1.7cM). Based on 270 shared SSR markers, most of the linkage groups were assigned to specific chromosomes. These results should further accelerate the genetic study of this crop.

Identification of single nucleotide polymorphism markers associated with resistance to bruchids (Callosobruchus spp.) in wild mungbean (Vigna radiata var. sublobata) and cultivated V. radiata through genotyping by sequencing and quantitative trait locus analysis.

BackgroundBruchid beetles are an important storage pest of grain legumes. Callosobruchus sp. infect mungbean (Vigna radiata) at low levels in the field, multiply during grain storage and can destroy seed stocks in a few months. Resistance against bruchid beetles has been found in wild mungbean V. radiata var. sublobata TC1966 and in cultivated mungbean line V2802.ResultsBruchid resistance data were obtained from recombinant inbred line populations TC1966 (V. radiata var. sublobata) × NM92 (F12) and V2802 (V. radiata) × NM94 (F7). More than 6,000 single nucleotide polymorphic markers were generated through genotyping by sequencing (GBS) for each of these populations and were used to map bruchid resistance genes. One highly significant quantitative trait locus (QTL) associated with bruchid resistance was mapped to chromosome 5 on genetic maps of both populations, suggesting that TC1966 and V2802 contain the same resistance locus. Co-segregation of all markers associated with resistance indicated the presence of only one major resistance QTL on chromosome 5, while QTL analysis based on physical map positions of the markers suggested the presence of multiple QTLs on different chromosomes. The diagnostic capacity of the identified molecular markers located in the QTL to correctly predict resistance was up to 100 %.ConclusionsMolecular markers tightly linked to bruchid resistance loci of two different mungbean resistance sources were developed and validated. These markers are highly useful for developing resistant lines.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0847-8) contains supplementary material, which is available to authorized users.

Comparative Efficacy of Insecticidal Plants on the Management of Groundnut Bruchid (Caryedon Serratus)

Laboratory study was conducted to determine the efficacy of insecticidal plant extracts Azadirachta indica A. (Juss), Lantana camara L. (Verbenaceae), Eupatorium odoratum L. (Asteraceae), Tephrosia vogelii Hook, Afromomum melegueta K.M. (Schumann) and Ocimum gratissimum (L) leaves against groundnut bruchid beetle (Caryedon serratus), and a synthetic insecticide (Cypermethrin) (10EC)) under ambient condition of temperature and relative humidity (30°C and 72%). One hundred grams of shelled groundnut was weighed into jute bags and treated with powders of the insecticidal plants. Both treated and untreated bags of groundnut were then infested with newly emerged adult of C. serratus (20 per bag) and covered. The experiment was laid out in Completely Randomized Design (CRD) and replicated four times. Parameters assessed included number of egg oviposited, number of eggs hatched (eclosion) and number of adults that emerged from each treatment, total developmental period (egg – adult), sex ratio of the emerged adults and finally percentage germination of the treated seeds. Data collected were analyzed using analysis of variance and treatment means were separated using Duncan multiple range tests at P ≤ 0.05 level of significance. Results showed that A. indica, L. camara, T. vogelli, A. melegueta and O. gratissimum treated seeds significantly recorded lowest mean number of eggs, reduced damage by C. serratus and increased germination percentage compared with E. odoratum and control. In conclusion, A. indica, L. camara, T. vogelli, A. melegueta and O. gratissimum have the potentials as alternatives to synthetic insecticides in the management of C. serratus by resource poor farmers.

Behavioral and physiological responses of the bean weevil Zabrotes subfasciatus to intraspecific competition

Zabrotes subfasciatus uses Phaseolus vulgaris seeds as its main host and reacts to variations in the availability of seeds by adjusting egg size and number. When faced to choose among different hosts, however, this insect shows the following preference hierarchy: bean > soy > lentil > chickpea, meaning that it is quite able to use species initially rejected as hosts for oviposition. Here, we investigated how this insect would react when placed in environments with different insect densities and allowed to choose between two types of seeds with contrasting levels of acceptability as substrates for oviposition. The experimental setting compared four levels of resource competition (density) by placing 1, 2, 4, or 6 couples within a Petri dish with 2 grains of P. vulgaris and 2 grains of Cicer arietinum. During the 7-day oviposition period, the following four behaviors were identified and quantified: fleeing, mating, inspecting P. vulgaris, and inspecting C. arietinum. We correlated these behaviors with fecundity. The most common behavior revealed by correspondence analyses plots was fleeing (searching for a new resource), followed by inspecting and mating (p < 0.001). Increasing competition diminished the inspecting behavior (of both hosts), reduced oviposition on P. vulgaris (the preferred host) and increased oviposition on C. arietinum (the less-preferred host), promoted fleeing and augmented the number of eggs glued to Petri dishes (egg dumping, p < 0.0001). Mating occurred mainly in situations of intermediate density. We previously demonstrated the existence of a preference hierarchy for different hosts and showed that artificial selection increases the oviposition preference for the less-preferred host. Here, we found that fleeing and egg dumping are the main strategies for avoiding competition and that these behaviors may support niche broadening in Z. subfasciatus.

Salvia officinalis essential oil in bean weevil control

ABSTRACT Bean weevil [Acanthoscelides obtectus Say (Coleoptera: Bruchidae)] is considered the main storage pest of the bean crop. Its control is performed mainly by chemical treatment, which has potential to cause resistance in pests, as well as environmental contamination. This study aimed at evaluating the insecticidal and repellent effect of Salvia officinalis L. essential oil against bean weevil. The doses used for the insecticidal test were: 0 L t-1, 0.5 L t-1, 1.0 L t-1, 1.5 L t-1, 2.5 L t-1 and 5.0 L t-1 of bean grains. For the mortality test, the experimental design was completely randomized, in a 6 × 7 (dose × time) factorial scheme, with five replications. The number of dead insects was counted at 2, 6, 12, 24, 48, 72 and 96 h after the insect introduction. The repellency test was conducted in arenas, under a completely randomized design, using the same doses applied to evaluate the insecticidal effect. Counts were performed 24 h after the introduction of insects. The insecticidal effect of the S. officinalis essential oil on A. obtectus resulted in mortality rates higher than 95 %, after 6 h of insect introduction, for all doses tested. Repellency effect was also detected for all doses tested.

Common bean seeds quality during storage under treatments with potential repellent of aromatic plants

ABSTRACT ndustrial chemicals that control pests in stored seed can cause damage to health by residual effects remaining in the grains. Studies of products with potential insecticide and repellent properties are required to decrease post-harvest losses. Thus, the aim of this study was to evaluate the quality and efficiency of seed treatment in beans stored under the following treatments: dried leaves and crushed laurel (Laurus nobilis L.), rosemary (Rosmarinus officinalis L.) and basil (Ocimum basilicum L.), cinnamon powder (Cinnamomum zeylanicum Breyn) and ground cloves (Syzygium aromaticum L.) over eight months. An untreated control and a treatment with diatomaceous earth were used to compare the results. At the beginning and at 30 days, percentages of normal and abnormal seedlings as well as seeds that did not germinate, mass of onehundred seeds, water content and infested seeds were analyzed. At 210 and 240 days, free choice arena and repellency testswere conducted. Treatments did not affect germination, mass of 100 seeds or water content; however, all plants tested showed a repellent effect on the bean weevil.

Calceolaria integrifolia s.l. complex, reduces feeding and growth of Acanthoscelides obtectus, and Epilachna varivestis. A new source of bioactive compounds against dry bean pests

Acanthoscelides obtectus Say (Coleoptera:Chrysomelidae) and Epilachna varivestis Mulsant (Coleoptera:Coccinellidae) are important predators of dry beans. Due to infestation during crop and storage, these insects affects the quality of seed and crop yields. This study aimed to investigate the effects of samples isolated from Calceolaria integrifolia sensu lato complex aerial parts, on A. obtectus and E. varivestis adults and larval development, respectively. The aerial parts of selected specimens of C. integrifolia s.l. Ehrhart complex (Calceolariaceae), C. integrifolia, C. talcana, C. andina, and the hybrid C. integrifolia x C. talcana were studied as insect growth regulators against dry bean insect pests. In addition to extracts and fractions, some mixtures of compounds were evaluated against the dry bean weevil (A. obtectus), and Mexican bean beetle (E. varivestis). Neem extract (with azadirachtin), gedunin, a known insect growth regulator isolated from Cedrela spp., Cedrela extract, some naphthoquinones and Malathion were used as positive controls. When tested for mortality on neonate larvae in a contact artificial diet bioassay, many samples, especially fractions of diterpenes, triterpenes and phenolic compounds, together with n-hexane and ethyl acetate extracts, at 500μg/cm2 caused significant mortality with 40–81% against A. obtectus and with 35.0–88.9% against E. varivestis, respectively. At lower concentrations, these substances exhibited growth reduction effects, such as strong repellency effects. They increased the development time of surviving larvae and a significant delay in time to pupation and adult emergence. Acute toxicity against larvae of E. varivestis was also found. In addition to n-hexane extract of C. andina and the hybrid (C. integrifolia x C. talcana), those fractions rich in diterpenes, quinones (mixture M5), azadirachtin, gedunin, Cedrela-MeOH-extract, juglone, plumbagin, 1,4-naphthoquinone and Malathion had the most potent lethal effect with values up to 79.0–100% at 500μg/cm2. In addition, fractions of these plants rich in triterpenes and flavonoids caused inhibition of growth at the same concentrations, whereas at minor concentrations they exhibited only moderate inhibitory activity. Many of samples assayed in this study had inhibitory activity comparable to gedunin and azadirachtin, which were used as positive controls. These results indicate that Calceolaria compounds may serve as desirable tools for protecting stored dry beans against A. obtectus and E. varivestis in small storage facilities as a component of environmentally friendly pest control strategies. Our work supports the use of extracts from C. species both as fumigants, repellent and contact bioinsecticides against stored product pests for crops of economic importance.

A gene encoding a polygalacturonase-inhibiting protein (PGIP) is a candidate gene for bruchid (Coleoptera: bruchidae) resistance in mungbean (Vigna radiata).

The Br locus confers bruchid resistance in mungbean; VrPGIP2 (encoding a polygalacturonase inhibitor) is a strong candidate gene for this resistance. The VrPGIP2 sequence differs between resistant and susceptible lines. Azuki bean weevil (Callosobruchus chinensis) and cowpea weevil (Callosobruchus maculatus) are serious insect pests of mungbean during storage. Bruchid resistance in mungbean is controlled by a single dominant locus, Br. Although the Br locus has been located on a genetic map, molecular basis and function of the gene remain unknown. In this study, high-resolution mapping using a BC11F2 population of 418 plants derived from a cross between 'Kamphaeng Saen 1' (KPS1; susceptible) and 'V2802' (resistant) using simple sequence repeat (SSR) markers delimited the Br locus to a genomic region of 38Kb of chromosome 5 containing two annotated genes. EST-SSR marker DMB-SSR158 co-segregated perfectly with the Br locus. Bioinformatics analyses revealed that DMB-SSR158 corresponds to a gene encoding a polygalacturonase inhibitor (polygalacturonase-inhibiting protein PGIP) and was designated as VrPGIP2. Comparison of VrPGIP2 coding sequences between four bruchid-resistant (V2802, V1128, V2817 and TC1966) and four bruchid-susceptible (KPS1, Sulu-1, CM and an unknown accession) mungbean lines revealed six single nucleotide polymorphisms (SNPs) between the resistant and susceptible groups. Three of the six SNPs resulted in amino acid changes; namely, alanine (A) to serine (S) at position 320, leucine (L) to proline (P) at position 332, and threonine (T) to P at position 335 of the VrPGIP2 sequence in resistant lines, compared with that in susceptible lines. The A to S change at position 320 may affect the interaction between PGIP and polygalacuronase. These results indicate that VrPGIP2 is very likely the gene at the Br locus responsible for bruchid resistance in mungbean.

Insecticidal Potentials of Lemon grass (Cymbopogon citratus) Products against Stored Cowpea Weevil (Callosobruchus maculatus) (F) (Coleoptera: Bruchidae)

Cowpea Weevil (Callosobruchus maculatus), the principal harvest pest of Cowpea, (Vigna unguculata) Order Coleoptera and family Bruchidae is of several economic importance reducing the yield and quality of stored Cowpea. In an attempt to eliminate the menace caused by this insect pest in an environmental friendly way, the insecticidal potentials of Lemon grass (Cymbopogon citratus) products were studied against this insect pest (Callosobruchus maculatus). Sundried fresh leaves of Lemon grass (C. citratus) were pulverized and sieved. The extract was obtained from the pulverized plant part using cold extraction method and ethanol as the solvent. The powder was test at dosage rate of 2.0, 2.5, 3.0 and 3.5g/10kg of experimental cowpea. The insecticidal potential of the extract was evaluated using test tube contact toxicity method at a concentration rate of 0.2, 0.3, 0.4 and 0.5ml/kg of experimental cowpea. Both powder and extract were evaluated for toxicity against C. maculatus at 24, 48, 72 and 96 hours exposure period, with three replicates per treatment. Results indicate that powder had significant difference (P<0.05) in adult C. maculatus mortality. The extract also had significant difference (P<0.05) in adult C. maculatus mortality after 96 h exposure with the highest dose producing 100% mortality. The result reveals that Lemon grass (Cymbopogon citratus) products have potential for use as protection of stored cowpea grains against damage by Callosobruchus maculatus.