Bean Weevil Acanthoscelides Obtectus Research Articles

THE INFLUENCE OF THE CHEMICAL COMPOSITION OF DIFFERENT ORIGIN BEANS (PHASEOLUS VULGARIS L.) ON TOLERANCE TO THE BEAN WEEVIL (ACANTHOSCELIDES OBTECTUS SAY) STROKE

Bean weevil Acanthoscelides obtectus Say is a very harmful pest. When pest control lacks it can produce 100% damages in stocked seeds. Research performed in Romania emphasized the importance of resistant or tolerant origins use besides the quarantine and fight measures in order to limit the stroke of this pest (Manolache et al., 1966; Marghitu et al., 1978). Research aimed to establish the chemical composition of the beans of different origins in the same time with correlation between the different chemical components and their tolerance against A. obtectus stroke.

Activity toward Bruchid Pest of a Kunitz-Type Inhibitor from Seeds of the Algaroba Tree (Prosopis juliflora D.C.)

A proteinaceous inhibitor with high activity against papain was found in seeds of the xerophytic algaroba tree (Prosopis julifora). The proteinase inhibitor Pj was purified using Sephacryl S-200 gel filtration followed by reverse-phase high-performance liquid chromatography on a Vidac 18 TP. Inhibitor Pj showed a Mr of 20,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a Mr of 19.2K by mass spectrometry. The inhibition of papain by the Pj inhibitor was the noncompetitive type, with a Ki value of 0.59 × 10−9 M. The gelatinase activity of papain was strongly inhibited by Pj too. The N-terminal amino acid sequence of the Pj inhibitor showed homology with the N-terminal amino acid sequence of the Kunitz-proteinase inhibitor family. Pj was strongly effective against digestive proteinases from bean weevil Acanthoscelides obtectus and cowpea weevil Callosobruchus maculatus and was moderately active toward midgut proteinases from pod weevil Mimosestes mimosae and Mexican bean weevil Zabrotes subfasciatus. The data shown here suggest that the protein present in algaroba seeds is involved with defense responses to insects and may be an important tool to be used in engineering plants resistant to bean weevils.

Residual activity of pirimifos-methyl and deltamethrin against plodia interpunctella hubner and sitotroga cerealella olivier in maize and acanthoscelides obtectus say in beans

Effects of contact insecticides pirimifos-methyl and deltamethrin of Indian meal moth Plodia interpunctella Hbn. and Angoumois grain moth Sitotroga cerealella Oliv. in maize, and on bean weevil Acanthoscelides obtectus Say in beans were examined 6 and 18 months after treatment in laboratory environment. Using appropriate methods (EPPO and other), maize and bean were treated with recommended and double rates of the insecticide products: EC formulation of pirimifos-methyl and EC formulation and dust of deltamethrin. After 6 and 18 months, we examined the mortality of P. interpunctella larvae, and 5. cerealella and A. obtectus adults following 2,7 and 14 days of contact with the treated material. In Angoumois grain moth and bean weevil, the resulting progeny was monitored up to FI generation. Both insecticides achieved full mortality of P. interpunctella larvae on the 6-month-old deposit. On the 18-months-old deposit, the same result was achieved with deltamethrin dust (both rates), as well as with pirimifosmethyl and deltamethrin (EC formulation) at the double recommended rates. S. cerealella mortality was 100% for both insecticides and both deposit ages. Regarding A. obtectus, full mortality of adults was found after contact with pirimifos-methyl and deltamethrin dust, while deltamethrin liquid caused low mortality of bean weevil, especially the 18-months-old deposit. FI generation adults of Angoumois grain moth and bean weevil were found only on 18-months-old deposits of the recommended rates of deltamethrin dust and pirimifos-methyl. The tested contact insecticides can provide very long prevention and control of Indian meal moth and Angoumois grain moth in stored maize and bean weevil in stored beens.

Increased mortality of Acanthoscelides obtectus by alkane-grown Beauveria bassiana

The effect of alkane-growth induction of theentomopathogenic fungus Beauveria bassiana(Balsamo) Vuillemin (Deuteromycotina:Hyphomycetes), on the ability to kill the beanweevil Acanthoscelides obtectus Say(Coleoptera: Bruchidae), was tested. Adultinsects were sprayed with an 0.01% Tween 20aqueous suspension of 4 × 106 conidia/ml.The performance of fungi grown in complete agarmedium containing glucose as carbon source(FS0) was compared to that of alkane-grownfungi (FS1) with n-hexadecane as the onlycarbon source. Mortality increased (p< 0.05) from 22 ± 4.5% to 44 ±11.4% at day 7, and from 26 ± 5.5% to 60± 7.1% 14 days after treatment withFS0 or FS1 respectively. The insectepicuticular hydrocarbons were analysed bycapillary gas chromatography (CGC); majorcomponents were saturated hydrocarbons, 27 to29 carbons in length. A variety ofmethyl-branched isomers of C27 were theprevailing structures, and nC27 was the majorstraight chain component. Whole insecthydrocarbons were qualitatively identical tothose of the epicuticular surface. Oleic,linoleic and palmitic acids accounted foralmost 88% of the fungal fatty acids,irrespective of the carbon source used forgrowth; however, the unsaturated/saturatedratio diminished markedly from 4.32(FS0) to 2.47 (FS1). These resultsindicate that alkane supplementation of culturemedia might be a tool to improve the virulenceof some mycoinsecticides.

Activity of wheat alpha-amylase inhibitors towards bruchid alpha-amylases and structural explanation of observed specificities.

Plant alpha-amylase inhibitors show great potential as tools to engineer resistance of crop plants against pests. Their possible use is, however, complicated by observed variations in specificity of enzyme inhibition, even within closely related families of inhibitors. Five alpha-amylase inhibitors of the structural 0.19 family were isolated from wheat kernels, and assayed against three insect alpha-amylases and porcine pancreatic alpha-amylase, revealing several intriguing differences in inhibition profiles, even between proteins sharing sequence identity of up to 98%. Inhibition of the enzyme from a commercially important pest, the bean weevil Acanthoscelides obtectus, is observed for the first time. Using the crystal structure of an insect alpha-amylase in complex with a structurally related inhibitor, models were constructed and refined of insect and human alpha-amylases bound to 0.19 inhibitor. Four key questions posed by the differences in biochemical behaviour between the five inhibitors were successfully explained using these models. Residue size and charge, loop lengths, and the conformational effects of a Cys to Pro mutation, were among the factors responsible for observed differences in specificity. The improved structural understanding of the bases for the 0.19 structural family inhibitor specificity reported here may prove useful in the future for the rational design of inhibitors possessing altered inhibition characteristics.

Comportement sexuel et stratégie reproductrice chez le Chryseida bennetti Burks (Hymenoptera: Eurytomidae), parasitoïde de la bruche du haricot. I. Effet de l'âge des partenaires

This paper relates a female age effect to the mating behavior of Chryseida bennetti Burks, an ectoparasitoid of the bean weevil (Acanthoscelides obtectus (Say)). The sexual behavior includes rapid courtship and copulation followed by a postmating courtship behavior ("guarding"). Male guarding behavior varies according to the females' age, with males guarding females of 2–3 days old longer than younger and older females. A period of sexual maturation is necessary for most of the males. Females' attractiveness begins at the pupal stage, and their receptivity on emergence. Mated females are still attractive to males. Multiple matings (up to four copulations) with the same male have been observed. The females' age seems to control copulation frequency and the duration of the postmating courtship behavior. Two- and three-day-old females had more successive multiple matings with the same male than the other females did, and males spent much more time guarding them. The age of the males (except from newly emerged males) did not seem to influence copulation frequency. On the other hand, the complexity of the sequential courtship behavior increased with the age of the partners. The function of males' postmating courtship is discussed.

Efficiency of plants from the South of France used as traditional protectants of Phaseolus vulgaris L. against its bruchid Acanthoscelides obtectus (Say)

The bean weevil Acanthoscelides obtectus Say is a major pest of Phaseolus vulgaris L. (kidney bean), one of the most important food pulses produced in South Western France. To protect the stored seeds against this pest, some farmers of this area traditionally used plants. The efficiency of these practices are tested and the effects of plants and botanicals on physiological behaviour of A. obtectus have been evaluated (ovipositional activity, growth inhibition and adult mortality). A statistical study shows significant differences in the tested plants (Allium sativum, Laurus nobilis, Tilia cordata sylvestris, Origanum serpyllum, Eucalyptus globulus, Cymbopogan nardus, Thymus vulgaris, Thymus serpyllum, Rosmarinus officinalis, Satureia hortensis). Plants from the family Labiatae provide the best direct and indirect insecticidal effect and among them, Origanum serpyllum is the most efficient.

Seed Predation by the Bean Weevil Acanthoscelides Obtectus on Phaseolus Species: Consequences for Seed Size, Early Growth and Reproduction

We examined potential implications of seed predation by the common bean weevil, Acanthoscelides obtectus for seed size variation in cultivated beans (Phaseolus vulgaris L., P. coccineus L. and P. lunatus L.) grown in common gardens. Significant seed size variation existed among different plants, among pods of differing seed number within plants, among successive seed crops within plants, and among seeds within pods. Within-plant sources of seed size variation were equally or more important than among-plant sources. Initial seed size strongly influenced early growth under laboratory and field conditions, and the advantage in early growth due to large seed size carried over to enhance subsequent plant reproduction in the field. Predationrelated shifts in seed and seedling size distributions apparently occurred without active selection by the bruchid. Oviposition that was evenly distributed among pods, but clumped within one or a few seeds within pods, allowed a greater proportion of seeds to escape from many-seeded pods. This, coupled with negative size/number relationships within and among plants, resulted in shifts toward smaller mean seed size. Due to nearly ubiquitous embryo damage by bruchid larvae, seed size of host plants was not related to tolerance to predation. We conclude that indirect sizeselective seed predation can have significant effects on maternal plant fitness both by altering the number of progeny produced, and by altering the fitness of surviving progeny.

Inheritance of resistance to Acanthoscelides obtectus in a wild common bean accession crossed to commercial bean cultivars

The bean weevil Acanthoscelides obtectus, is an important storage pest of common beans in Latin America and Africa. A few wild bean accessions from Mexico have been identified as highly resistant to the weevil. One accession, G 12952, was crossed to two susceptible bean cultivars differing in seed size. Reciprocal F1 and F2 individual seed were evaluated for days to adult emergence (DAE) and emerged adult weight. Maternally inherited seed size affected resistance measurements only in the F1 reciprocal crosses, however, the overall resistance level of the F1 was more similar to that of the susceptible cultivars. The F2 showed a continuous, but skewed distribution from low to high DAE. Very few F2 individuals had the resistance level of G 12952. When the frequency distributions were divided into discrete categories based on parental response, resistance was found to be inherited as two recessive complementary genes. The F3 generation showed an overall lowering of resistance levels compared to their original F2 evaluations. However, none of the lines classified as resistant (≥50 DAE) in the F2, fell into the susceptible category in the F3, indicating that the resistant genotypes were relatively stable as expected with recessively inherited traits. Modifying genes from the commercial parents may be responsible for general lowering of resistance. Seed size was negatively correlated with adult weight but not with DAE. The unique resistance of the wild bean accessions is discussed in relation to its inheritance. The results and obstacles encountered in the A. obtectus breeding program at CIAT are described.

The effects of selection for early and late reproduction on fecundity and longevity in bean weevil (Acanthoscelides obtectus)

In the bean weevil (Acanthoscelides obtectus) selection for early and late reproduction was performed both under minimal stress and when adults were subjected to starvation. We obtained direct responses to selection in both early and late reproducing lines, but only under stressful conditions. Mortality rate differences between lines selected for early and for late fecundity were not observed. These findings suggest that the bean weevil has a genetic system which allows a nearly independent adjustment of age-dependent fecundity and mortality.

Morphology and ultrastructure of the abdominal integumentary glands of Acanthoscelides obtectus Say (Coleoptera : Bruchidae)

The morphology of the abdominal integumentary glands of the bean weevil Acanthoscelides obtectus (Coleoptera : Bruchidae) is described. There are 2 types: glands with long secretory ducts and ampullate glands with short ducts. The former are distributed throughout the integument and have 2 secretory cells, one of which is connected to the reservoir in the distal receptor zone, and the other to the duct. The duct, which is 100 μm long, has an epicuticular structure and its evacuation pore is 0.5 μm in diameter. It is surrounded by cytoplasm rich in microtubules. The epicuticular structure of the duct is resolved into fine filaments in the distal region. The ampullate glands exist only on the abdominal tergites and the pygidium. They are composed of an epicuticular receptor ampoule and a short duct connected to one secretory cell. The 2 types of glands can be placed in class 3 according to the nomenclature of Noirot and Quennedey (1974. Annu. Rev. Entomol. 19: 61–80).

Mechanism of seed lectin tolerance by a major insect storage pest of Phaseolus vulgaris, acanthoscelides obtectus

AbstractThe bean weevil Acanthoscelides obtectus (Say) is a major storage peat of Phaseolus vulgaris L (kidney, haricot bean). The seeds of P vulgaris contain high levels (up to 30 mg g−1 DM) of lectin, which has been shown to be toxic towards larvae of the related bruchid storage pest of cowpea, Callosobruchus maculatus F. The lack of toxicity of this lectin towards larvae of A obtectus is demonstrated. Unlike the strong binding of lectin to the midgut epithelium observed in larvae of C maculatus, no binding of lectin molecules was found to occur in the gut epithelial cells of A obtectus. This observation provides the basis for a hypothesis explaining the lack of toxicity of P vulgaris lectin towards A obtectus. Assays of proteolytic activity in gut homogenates of C maculatus and A obtectus suggest that the difference in susceptibility of the two insects towards the toxic effects of the lectin is not due to differential inactivation by proteolysis. Besides its effects on larval development, the lectin has a further effect at pupation, causing disruption of adipose tissues in C maculatus but having no effect on A obtectus.

Effets inhibiteurs de la présence d'un congénère sur la maturation des ovocytes chez Acanthoscelides obtectus Say (Coléoptère: Bruchidae)

The bean weevil Acanthoscelides obtectus, which is found over a large geographical area, can live in habitats where its host plant is not continuously available throughout the year. In such cases, the females must wait for favorable egg-laying conditions during part of the year. Individuals of this species may concentrate in temporary shelters such as dry leaves for example. The effect of the grouping of two individuals (female and male; female and female) on the reproductive physiology of females from a Cuban strain led to an inhibition or a decrease in oogenesis. This phenomenon was also observed when a female cohabited with a male whose aedeagus had been removed. However, oocyte maturation was stimulated when 4-day-old females were placed in the presence of a male for 4 h. The variability observed between two generations is discussed along with the often neglected role of relationships among individuals. The adaptive role of the inhibition of oocyte maturation induced by the grouping of two individuals is discussed.

Longevity and Egg Production in the Common Bean Weevil, Acanthoscelides Obtectus (Say)1

Reproductive activity and duration of life are two biological variables which play important roles in the economy of any species. The relationships between them have not only broad biological significance but also, in many cases, considerable economic importance. Hence detailed studies of reproduction and longevity in particular species are of general as well as specific interest. The common bean weevil (Acanthoscelides obtectus (Say)) has proven to be a highly satisfactory species for such studies; its reproductive activity can be measured by egg counts and its duration of life in days. Since relatively few data on these biological variables are available for insects, we present here a summary of the features of egg production by mated and unmated females and longevity of mated and unmated individuals. The results are analyzed statistically and compared with those of similar studies reported for other insects.