When cowpea grain is stored in airtight containers, destructive populations of the cowpea bruchid (Callosobruchus maculatus) don't develop even though the grain put into the store is already infested with sufficient C. maculatus to destroy the entire store within a few months. The surprising effectiveness of hermetic storage for preserving grain against insect pests has long been linked with the depletion of oxygen in the hermetic container and with the parallel rise in carbon dioxide. With C. maculatus, low oxygen (hypoxia) leads to cessation of larval feeding activity, whereas elevated levels of carbon dioxide (hypercarbia) have little or no effect on feeding. Cessation of feeding arrests the growth of the insects, which don't mature and don't reproduce. As a result, population growth ceases and damaging infestations don't develop. C. maculatus eggs, larvae, and pupae subjected to hypoxia eventually die after exposures of various duration. The cause of death is desiccation resulting from an inadequate supply of water. We demonstrate that blocking the supply of oxygen interdicts the main supply of water for C maculatus. This leads to inactivity, cessation of population growth, desiccation and eventual death. (C) 2012 Elsevier Ltd. All rights reserved.

Avidin, a large protein from egg whites, powerfully binds biotin, a vitamin for many insects. When avidin was incorporated into the diets of larval Callosobruchus maculatus (F.), the cowpea bruchid, at relatively low levels (10–30ppm), there was a marked dose-dependent increase in mortality, as well as a small increase in the developmental time of survivors. Avidin toxicity was prevented when biotin was added to the diet together with avidin. Sub-lethal doses of avidin caused reductions in fecundity. Avidin had no effect on the larval feeding rates during the first three instars, even when the larvae were consuming amounts of the protein that would later cause death. In the fourth instar there was a dose-dependent reduction in the rates of feeding as the avidin level in the food increased. Death of the C. maculatus larvae usually occurred at the pupal/adult stage still within the host seed. Streptavidin, a biotin-binding protein from a bacterial source, had effects similar to chicken egg avidin.

The cowpea bruchid, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae: Bruchini), is a worldwide pest of stored cowpea grain [ Vigna unguiculata (L.) Walp. (Leguminosae)], causing tens of millions of dollars’ worth of damage annually. One method of managing this pest involves planting cultivars whose seeds are resistant to bruchids. Despite extensive research, we still do not know the mechanism by which TVu 2027, the original resistant cowpea line, resists C. maculatus . Using micro‐CAT (computerized axial tomography) scan imaging, we visualized the feeding patterns of bruchids living and growing within cowpea seeds. We present evidence that an interior zone in TVu 2027 seeds is responsible for the high mortality and developmental delays experienced by avirulent larval bruchids. We observed that both virulent as well as avirulent bruchid strains have different feeding patterns in TVu 2027 seeds compared to susceptible seeds. It appears that the resistance factor is most concentrated in a zone in each cotyledon adjacent to the air space separating the two seed halves.

Two hairpin-loop domains in cystatin family proteinase inhibitors form an interface surface region that slots into the active site cleft of papain-like cysteine proteinases, and determine binding affinity. The slot region surface architecture of the soybean cysteine proteinase inhibitor (soyacystatin N, scN) was engineered using techniques of in vitro molecular evolution to define residues that facilitate interaction with the proteinase cleft and modulate inhibitor affinity and function. Combinatorial phage display libraries of scN variants that contain mutations in the essential motifs of the first (QVVAG) and second (EW) hairpin-loop regions were constructed. Approximately 1010-1011 phages expressing recombinant scN proteins were subjected to biopanning selection based on binding affinity to immobilized papain. The QVVAG motif in the first hairpin loop was invariant in all functional scN proteins. All selected variants (30) had W79 in the second hairpin-loop motif, but there was diversity for hydrophobic and basic amino acids in residue 78. Kinetic analysis of isolated scN variants identified a novel scN isoform scN(LW) with higher papain affinity than the wild-type molecule. The variant contained an E78L substitution and had a twofold lower Ki (2.1 pM) than parental scN, due to its increased association rate constant (2.6 +/- 0.09 x 107 M-1sec-1). These results define residues in the first and second hairpin-loop regions which are essential for optimal interaction between phytocystatins and papain, a prototypical cysteine proteinase. Furthermore, the isolated variants are a biochemical platform for further integration of mutations to optimize cystatin affinity for specific biological targets.

Experiments conducted in Maroua, Cameroon, demonstrated that a large 50-kg-capacity solar heater can be used to successfully eradicate infestations of Callosobruchus maculatus from cowpea seeds kept in small, transparent Minigrip® ziplock plastic bags. Differences in temperature were noted in ziplock bags from different locations within the solar heater, but these were slight and not significant. Temperatures produced inside the heater were sufficient to kill all developing insects living within infested cowpea seeds. Small, transparent ziplock plastic bags are useful seed storage containers for short-term cowpea germplasm collections and are easily inspected during storage following solar disinfestation. Published reports indicate that temperatures of up to 85 °C do not adversely affect seed germination, germination rates, or seedling viability. These temperature and biological experiments provide evidence that the solar heater technique can serve as an effective and practical means to improve the short-term storage of cowpea seeds in developing country national agricultural research programs

Accessions of Vigna vexillata, Vigna oblongifolia, and Vigna unguiculata (subspecies unguiculata, dekindtiana, and pubescens) were evaluated under laboratory conditions to identify sources of seed and/or pod resistance to the cowpea weevil Callosobruchus maculaius. TVnu 37 and TVnu 88 (V. oblongifolia) and TVnu 72 (V. vexillata) possessed high levels of seed resistance. On mature, dry pods, seventeen-fold differences in mean eggs laid/cm2 were observed, suggesting that ovipositional nonpreference could be a practical form of resistance to C. maculatus. In infested pods, pre-establishment larval mortality (mortality before larvae become established in seeds) varied among accessions, ranging from 19.3% in Nl 778 (cv-gr. Biflora) to 91.3% in NI 816 (cv-gr. Textilis). The total percentage larval mortality in infested pods ranged from 34.6% in TN 88-63 (V. unguiculata) to 100% in TVnu 72 (V. vexillata) and NI 816 (cv-gr. Textilis) with the majority of accessions producing over 80% mortality. Higher levels and more durable forms of bruchid resistance might be achieved by combining seed and pod resistance.

Exposing cowpeas to temperatures 2≤57.3°C in an oven for 1 h killed cowpea weevil larvae and pupae living within the seeds, and cowpea weevil adults living among the seeds. Using only the sun's rays and a simple heater constructed from cheap, widely available materials, we demonstrated the feasibility of using solar energy to eliminate cowpea weevil from cowpea stores. The temperatures and exposure times necessary to disinfest cow peas had no significant effect on the cooking time and percentage germination of cowpea seeds. Solar disinfestation of cowpea stores using simple technology represents a new approach to preserving cowpeas from weevil attack, which may be useful at the level of subsistence farms in developing nations.

There are claims that phytohemagglutinin (PHA), the lectin of common bean, Phaseolus vulgaris, is toxic when fed to the cowpea weevil, Callosobruchus maculatus, and that PHA serves as the chemical defense against this seed-feeding bruchid beetle (DH Janzen, HB Juster, IE Liener [1976] Science 192: 795-796; AMR Gatehouse, FM Dewey, J Dove, KA Fenton, A Pusztai [1984] J Sci Food Agric 35: 373-380). However, our studies indicate that neither PHA nor its isolectins have detrimental effects when fed to the cowpea weevil. To explain these contradictory results we characterized the commercial lectin source used by A. M. R. Gatehouse, F. M. Dewey, J. Dove, K. A. Fenton, A. Pusztai (1984, J Sci Food Agric 35: 373-380). We demonstrate here that the toxic effects of PHA to cowpea weevil are due to an alpha-amylase inhibitor contaminant in the commercial preparation.

AbstractAn artificial bean seed system was used to evaluate the effects of a cysteine proteinase inhibitor (E‐64) and a serine proteinase inhibitor (Bowman‐Birk inhibitor) on the developmental time and mortality of the common bean weevil, Acanthoscelides obtectus (Say). These inhibitors were incorporated into artificial bean seeds on which the insect fed. To better understand the mode of action of these inhibitors, free amino acids were also added to the seeds, alone and in combination with the inhibitors. E‐64 was found to be highly effective in delaying development and increasing mortality of the insect. Both effects were directly related to the concentration of E‐64. Bowman‐Birk inhibitor had little effect on these parameters. Assays of gut proteolytic activity of insects reared on artificial seeds with various levels of E‐64 demonstrated a direct relationship between E‐64 concentration in the diet and reduction of gut proteolytic activity. Free amino acid supplementation to the diet did not prevent inhibition of gut proteolytic activity by E‐64, but did reverse its effects on developmental time and mortality, strengthening the hypothesis that E‐64 operates by inhibition of essential digestive proteinase activity.RésuméEffets de 2 inhibiteurs de protéinases, E‐64 et inhibiteur Bowman‐Birk sur la durée de développement et la mortalité d' Acanthoscelides obtectusDes grains artificiels de haricot ont été utilisés pour évaluer les effets sur la durée de développement et la mortalité d' Acanthoscelides obtectus. Say d'inhibiteurs de la protéinase de la cystéine (E‐64) et de la protéinase de la sérine (l'inhibiteur de Bowman‐Birk). Ces inhibiteurs avaient été incorporés dans les grains artificiels. Pour mieux comprendre leur voie d'action, des acides aminés libres étaient ajoutés à ces graines, seuls ou combinés aux inhibiteurs. E‐64 a très efficacement retardé le développement et accru la mortalité; ces 2 effets étaient liés à sa concentration. L'inhibiteur de Bowman‐Birk a eu peu d'effets sur ces paramètres. Des expériences sur l'activité protéolytique du tube digestif d'insectes élevés sur des graines artificielles avec différentes concentrations de E‐64 ont montré une relation directe entre la concentration en E‐64 et la réduction de l'activité protéolytique. L'addition d'acides aminés libres dans l'aliment n'a pas empêché l'inhibition de l'activité protéolytique par E‐64, mais a inversé ses effets sur la durée de développement et la mortalité, renforçant l'hypothèse que E‐64 agit en inhibant l'activité protéinase digestive essentielle.

Crop ScienceVolume 26, Issue 1 cropsci1986.0011183X002600010064x p. 205-205 Registration of Germplasms Registration of 81IND-2 Glandular-Haired Alfalfa Germplasm R. E. Shade, R. E. ShadeSearch for more papers by this authorL. W. Kitch, L. W. KitchSearch for more papers by this author R. E. Shade, R. E. ShadeSearch for more papers by this authorL. W. Kitch, L. W. KitchSearch for more papers by this author First published: 01 January 1986 https://doi.org/10.2135/cropsci1986.0011183X002600010064xCitations: 8AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume26, Issue1January–February 1986Pages 205-205 RelatedInformation

Journal Article An Alfalfa Weevil Larval Resistance Mechanism Detected in Medicago Get access R. E. Shade, R. E. Shade Department of Entomology, Purdue University, West Lafayette, Indiana 47907 Search for other works by this author on: Oxford Academic PubMed Google Scholar T. E. Thompson, T. E. Thompson Department of Entomology, Purdue University, West Lafayette, Indiana 47907 Search for other works by this author on: Oxford Academic PubMed Google Scholar W. R. Campbell W. R. Campbell Department of Entomology, Purdue University, West Lafayette, Indiana 47907 Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Economic Entomology, Volume 68, Issue 3, 1 June 1975, Pages 399–404, https://doi.org/10.1093/jee/68.3.399 Published: 01 June 1975 Article history Received: 01 November 1974 Published: 01 June 1975

Crop ScienceVolume 14, Issue 4 cropsci1974.0011183X001400040052x p. 609-609 Registration of Germplasms Registration of Indiana Syn. C Alfalfa Germplasm1 (Reg. No. GP 43) T. E. Thompson, T. E. ThompsonSearch for more papers by this authorJ. D. Axtell, J. D. AxtellSearch for more papers by this authorR. E. Shade, R. E. ShadeSearch for more papers by this authorR. D. Meeks, R. D. Meeks Formerly Assistant Professor, Department of Agronomy (Presently Research Geneticist ARS, USDA, North Dakota State University, Fargo, ND 58102), Associate Professor, Department of Agronomy, Assistant Professor, Department of Entomology, and former Graduate Research Assistant, Department of Agronomy, Purdue University, West Lafayette, IN 47907.Search for more papers by this author T. E. Thompson, T. E. ThompsonSearch for more papers by this authorJ. D. Axtell, J. D. AxtellSearch for more papers by this authorR. E. Shade, R. E. ShadeSearch for more papers by this authorR. D. Meeks, R. D. Meeks Formerly Assistant Professor, Department of Agronomy (Presently Research Geneticist ARS, USDA, North Dakota State University, Fargo, ND 58102), Associate Professor, Department of Agronomy, Assistant Professor, Department of Entomology, and former Graduate Research Assistant, Department of Agronomy, Purdue University, West Lafayette, IN 47907.Search for more papers by this author First published: 01 July 1974 https://doi.org/10.2135/cropsci1974.0011183X001400040052x 1 Registered by the Crop Science Society of America. Published with the approval of the Purdue University Agricultural Experiment Station. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue4July–August 1974Pages 609-609 RelatedInformation

The study of the cereal leaf beetle, Oulema melanopus (L.), (Coleoptera: Chrysomelidae) was conducted in 1966 in 2 oat fields with different population densities in Indiana. The average number of eggs deposited per linear foot of row was 194 in the high-density field and 59 in the low-density field. All the eggs used to assess egg mortality in both study groups were 1 day old on May 20, when the study was begun. In the low-density field egg mortality from all causes was 60.3%. Predation by adults of the lady beetle Coleomegilla maculata (De Geer) and the convergent lady beetle, Hippodamia convergens Guérin-Méneville, was the primary biological factor causing egg mortality. The adults and larvae of these 2 coccinellids were also the primary biological agents responsible for larval mortality. Larval mortality from all causes was 72%. Prepupalpupal mortality was 42%. A total mortality of 93.8%, from day-old eggs to newly emerged adults, occurred in the low-density field Adults of the same 2 species of coccinellids were also the primary biological agents responsible for egg mortality in the high-density field. Egg mortality from all causes was 52.2%. Adults and larvae of these 2 coccinellids were the primary biological agents responsible for larval mortality, while rainstorm activity was the major physical factor. Larval mortality from all causes was 58.5%. Prepupal-pupal mortality was 54.5%. The total mortality in the high-density field, from day-old eggs to newly emerged adults, was 91.2%. Additional observations showed that larval mortality late in the season occurred when larval feeding depleted the food supply. Larval mortality caused by rainstorm activity in the high-density field following each of 2 rainstorms was 14.5 and 13.5%, respectively. Mortality of newly emerged adults in the high-density field ran as high as 2.8 per linear foot of row. This mortality was attributed to larval competition for a limited food supply prior to pupation, effects of high soil temperatures and low soil moisture during the pupal period, and lack of an immediate source of food and moisture for the adults upon emergence from pupae.

Journal Article Leaf-Vein Spacing as a Factor Affecting Larval Feeding Behavior of the Cereal Leaf Beetle, Oulema melanopus (Coleoptera: Chrysomelidae) Get access Richard E. Shade, Richard E. Shade Department of Entomology, Purdue University, Lafayette, Indiana Search for other works by this author on: Oxford Academic Google Scholar M. Curtis Wilson M. Curtis Wilson Department of Entomology, Purdue University, Lafayette, Indiana Search for other works by this author on: Oxford Academic Google Scholar Annals of the Entomological Society of America, Volume 60, Issue 3, 15 May 1967, Pages 493–496, https://doi.org/10.1093/aesa/60.3.493 Published: 15 May 1967 Article history Accepted: 19 December 1966 Published: 15 May 1967

In laboratory studies conducted during 2 winters, using 23 species of Gramineae and under 2 sets of environmental conditions, larvae of Oulema melanopa (L.) were transferred to the various food plants within 8 hr of eclosion and were observed for survival and development. Contrary to results reported by others, the cereal leaf beetle was found not to be polyphagous within the family Gramineae. Several plants, notably species of Setaria, Echinocloa, and Arundinaria, exhibited antibiosis. Generally, the small grains (oats, barley, wheat, spelt, and rye) were superior food plants. Some forage grasses were favorable, but usually the larval development on them was slower than on the small grains.