Bruchid Infestation Research Articles

Effects of a plant resistance protein on parasitism of the common bean bruchid Acanthoscelides obtectus (Coleoptera: Bruchidae) by its natural enemy Dinarmus basalis (Hymenoptera: Pteromalidae)

Abstract Dinarmus basalis is an important larval parasitoid of the bean bruchid Acanthoscelides obtectus , a major pest of stored legumes throughout the tropical belt. The use of a combination of different natural resources for protecting stored beans from attack by A. obtectus by non-toxic means is considered a promising alternative to the use of traditional chemical insecticides. The seed storage protein arcelin causes sub-lethal effects on the development of A. obtectus that are favorable for biological control. The present study aimed to validate the mutual compatibility between the plant resistance factor arcelin and the biological control candidate D. basalis . Development and performance of D. basalis attacking A. obtectus on beans with different relative arcelin concentrations were investigated in bioassays. The parasitoid accepted hosts on all tested bean lines, irrespective of the relative concentration of arcelin. No indications were found for an effect of arcelin on parasitoid offspring fitness. The parasitoid’s capability to suppress bruchid development was investigated in a follow-up experiment mimicking the temporal complexity of bruchid infestations in the field. Bruchid suppression was significantly higher on arcelin containing bean lines than on arcelin-free cultivars. Our findings demonstrate the potential of the candidate biological control agent D. basalis to contribute to a marked reduction of bruchid emergence in a proposed two-component integrated pest management system.

The Effect of Dung and Dispersal on Postdispersal Seed Predation of Attalea phalerata (Arecaceae) by Bruchid Beetles1

ABSTRACTLow postdispersal mortality of palm seeds in tapir dung is hypothesized to result from the mechanical barrier provided by dung against bruchid infestation and/or from the distance to adult palms at which seeds are dispersed. We tested these hypotheses by distributing endocarps of Attalea phalerata Mart. ex Spreng. in experimental dung piles in Beni, Bolivia. Predation rates were significantly lower for seeds covered by dung than for exposed or partially covered seeds, but did not differ between seeds placed below and 50 m away from palms. Thus, dung, not short‐distance dispersal, protects seeds against bruchid beetles, and may ultimately promote survival of palm seeds.

Characterization of Resistance to <I>Callosobruchus maculatus</I> (Coleoptera: Bruchidae) in Mungbean Variety VC6089A and Its Resistance-Associated Protein VrD1

Characteristics of resistance of VC6089A, a mungbean, Vigna radiata (L.) Wilczek, bred by using a wild Vigna species, V. sublobata (Roxburgh) Verdcourt (accession no. TC1966), and containing a novel protein, VrD1, were investigated against the cowpea weevil, Callosobruchus maculatus (F.). The seeds of VC6089A showed high level of resistance; > 96% of the bruchid eggs failed to develop into adults, whereas 85% of eggs laid on susceptible cultivar VC1973A became adults. Mortality of surviving bruchids raised for five generations on VC6089A remained higher than 96%; however, female adults maintained high fecundity and thus showed a positive population growth through these generations. We therefore cannot exclude the possibility that the beetles could develop resistance to the resistant mungbean VC6089A. The protein VrD1 purified from seeds of VC6089A showed marked toxicity to C. maculatus when beetles were reared on artificial seeds containing varying levels of VrD1. Thorough inhibition of development was observed when artificial seeds containing 0.2% (wt:wt) VrD1 was provided for insect feeding. Our findings demonstrated the insecticidal activity of VC6089A mungbean seeds and VrD1 protein against C. maculatus. These results may facilitate safer control against bruchid infestation.

Bruchid (Coleoptera: Bruchidae) Ovicidal Phenylbutanoid from <I>Zingiber purpureum</I>

The larvicidal activity of the dichloromethane extract of Zingiber purpureum Roscoe (Zingiberaceae) rhizome against the second instar of Aedes aegypti (L.) (Diptera: Culicidae) is shown to be due to 4-(3',4'-dimethoxyphenyl)buta-1,3-diene. The diene also showed ovicidal activity against the bruchid Callosobruchus maculatus (F.) (Coleoptera: Bruchidae). Most of the eggs laid by bruchids on treated cowpea seeds were transparent, and very few of them contained developing embryos. The few larvae produced from these embryos were unable to penetrate the seed coat and enter the seed. Similar effects were seen when adults were exposed to the compound and then placed on untreated cowpea seeds, suggesting that a new type of maternally mediated ovicidal effect was involved. Coated and impregnated granular formulations of the extract were evaluated for use in the control of bruchid infestation of stored cowpea seeds. Coated granules showed activity similar to that of the crude extract but were found to lose activity rapidly. Impregnated granules were found to be less active than the crude extract.

Effect of Pre-harvest Sprays of Neem (Azadirachta indica A. Juss) Seed Products and Pirimiphos-methyl and Harvest Time Modification on Infestation of Cowpeas by Storage Bruchids in the Field and Store in Maiduguri, Nigeria

The efficacy of combining three harvesting times with pre-harvest spray of two botanicals obtained from neem seeds and the synthetic contact insecticide pirimiphosmethyl in reducing field infestation of cowpea pods was investigated in Maiduguri located in the Sudan savanna zone of northeastern Nigeria during the cropping seasons of 2001 and 2002. The harvesting times included harvesting dry cowpea pods 3 weeks after ripening (WAR) commenced, as well as 4 and 5 WAR. Neem seed oil (NSO) was mixed with water and applied at the rate of 20 ml/L, aqueous neem seed extract (ANSE) applied as filtrate obtained from soaking neem powder in water at the rate of 50 g/l and pirimiphosmethyl (Actellic 25 EC)(PMM) was applied at the rate of 2 ml/L to plants in experimental plots at each of the harvesting times. Unsprayed plots were included in the trials to serve as control. In both cropping seasons, pods from plots protected with the botanicals/insecticides were infested significantly less with bruchid eggs than pods from unsprayed plots. In the 2002 cropping season. storage bruchid eggs infested results showed that pods that were harvested 5 WAR significantly more than pods that were harvested 3 or 4 WAR. The percentage of insecticide-protected pods that were infested with bruchid eggs was significantly lower than that of unprotected pods in the 2001 cropping season. Bruchid infestation generally increased with delayed harvesting in both seasons. In 2001, percentage of pods that were protected with ANSE end harvested 5 WAR were infested significantly more with bruchid eggs than pods

The role of chemical cues in host finding and acceptance by Callosobruchus chinensis

We studied the response of female Callosobruchus chinensis to chemical cues emitted by cowpea seeds at different stages of bruchid infestation (uninfested, egg carrying, L1-, and L4-infested). Olfactory attractiveness was determined in Y-tube olfactometer assays by testing individual seed categories against either clean air or uninfested seeds. Oviposition preferences between uninfested and infested seeds were determined in petri-dish choice-experiments. The olfactometer assays revealed that weevils discriminate between seeds containing different stages of developing bruchids on the basis of olfactory cues. While odors from uninfested and egg-carrying seeds acted as attractants, odors from L1- and L4-infested seeds failed to induce a positive response by the bruchids. When given a choice between uninfested and infested seeds in the olfactometer, weevils preferred uninfested seeds over L1- and L4-infested seeds, but failed to distinguish between uninfested and egg-carrying seeds. In the oviposition experiment as well, bruchids showed a distinct preference for uninfested seeds when offered in combination with L1- and L4-infested seeds. This experiment further showed a reduced acceptance of egg carrying seeds. Our results indicate that C. chinensis females use chemical information during both host searching and host acceptance. Volatiles from uninfested or egg carrying seeds act as attractants, while deterrence increases as development of bruchid immature stages progresses.

The efficacy of harvest time modification and intercropping as methods of reducing the field infestation of cowpeas by storage bruchids in Kenya

A study was carried out in Eastern Province, Kenya to evaluate whether the harvesting of cowpeas at different times and intercropping with maize were effective in reducing field infestation by storage bruchids. Cowpea seed harvested very late (4 weeks after the recommended harvest time) was infested by storage bruchids to a significantly greater extent than cowpeas harvested early or at the recommended harvest time. The intercropping experiments showed that bruchid infestation was significantly reduced in the intercropped cowpeas. These results are discussed in view of the current cowpea farming systems in Kenya.

Effect of Callosobruchus chinensis (Bruchid) infestation on antinutritional factors in stored legumes.

Effect of bruchid infestation on selected antinutritional factors, saponin, phytic acid and trypsin inhibitor activities, of three (mung bean, chickpea and pigeon pea) legumes stored for six months was studied. The three antinutritional factors, saponin, phytic acid and trypsin inhibitor activity (TIA), increased with increased storage period. Saponin, phytic acid and trypsin inhibitor activity values were significantly lower in control samples compared to stored infested samples. The difference between the contents of antinutritional factors were significant (p < 0.05) during different storage periods.

Acacia Seed Predation by Bruchids in an African Savanna Ecosystem

1. Acacia tortilis, A. nilotica and A. mellifera seeds on the ground suffered greater bruchid infestation than seeds within canopy held pods. 2. Seeds of indehiscent and dehiscent Acacia species showed no difference in the rate of bruchid infestation. More bruchid species attacked seeds of indehiscent (A. nilotica, A. tortilis, A. hebeclada and A. robusta) than dehiscent (A. karroo, A. mellifira and A. caffra) species. 3. Bruchid infestation differed between A. tortilis trees, and for A. tortilis and A. hebeclada, differed between years. There was no difference in bruchid attack on A. nilotica between years. 4. Stored Acacia seeds were infested more than fresh seeds. 5. The results of this research have important implications for re-afforestation programmes with Acacia trees in Africa. Pods should be collected from the canopies of Acacia exhibiting low bruchid infestation, the length of seed storage should be minimized and seeds susceptible to the same bruchid species should not be stored together.

The association between some physico-chemical characteristics and susceptibility of cowpea ( Vigna unguiculata (L.) Walp) to Callosobruchus maculatus (F.)

The association between some physical characteristics and the tannin content of cowpea ( V. unguiculata), and the susceptibility of the beans to bruchid ( C. maculatus) infestation was investigated. The physical characteristics were the coat colour and texture, seed height, length and width, and the thickness of the seed coat. The dimensional parameters show significant ( P < 0.05) correlation with the number of eggs laid with the seed height accounting for about 70% of the variance. The same parameter accounted for 77% of the variance in the number of F 1 progeny. The tannic acid content, however, becomes increasingly significant with the growth of the larvae to adulthood. The tannic acid content accounted for 14.3 and 39.9% of the variance in the number of F 1 progeny and percentage adult emergence, respectively.

Predispersal Seed Predation in Leguminous Species: Seed Morphology and Bruchid Distribution

We measured and calculated seed morphological parameters [axonometric linear measures, weight, volume and minimum-maximum seed size ratio (SMIMA)] of 110 leguminous plant species occurring in Hungary. We collected seed samples, reared the predispersal seed predators from the samples, took morphological data from the bruchids (elytra length, body width, thorax length) and calculated the body size ratio (BSR). We found that SMIMA and BSR were fairly good predictors of bruchid infestation patterns at plant tribe, species and sample (locality) levels. Bruchid body length was much less variable than the parameters (e.g., volume) of seeds from which they were reared. We also found that the closer the shape of the seeds of a leguminous plant species to a sphere, or the larger the seed volume, the higher the probability of bruchid infestation. Seed morphological traits (weight, volume and SMIMA) clearly separated the hosts of the genera Bruchus and Bruchidius. For the three related bruchid genera studied, phylogenetic and ecological effects (regarding seed shape preference) were also separated. We concluded that the evolution of the seed size of plant species studied is not likely driven by bruchids or by other seed predators

Transgenic Pea Seeds Expressing the α-Amylase Inhibitor of the Common Bean are Resistant to Bruchid Beetles

Infestations of stored legume seeds by bruchid beetles, such as the cowpea weevil and the Azuki bean weevil cause substantial economic and nutritional losses of these food crops, especially in developing countries. Seeds of the common bean are resistant to these bruchids largely because of the presence of α-amylase inhibitor (αAI-Pv), a seed protein that is toxic to the larvae. The αAI-Pv gene is therefore a candidate for a genetic engineering approach that would make other legumes (pea, chickpea, cowpea, Azuki bean) resistant to bruchid infestations. We tested this possibility by transforming peas (Pisum sativum) with the αAI-Pv gene driven by a strong seed-specific promoter. The levels of αAI protein in the pea seeds were as high as in bean seeds and the peas were resistant to the cowpea and Azuki bean weevils.

The fate of mature African Acacia pods and seeds during their passage from the tree to the soil

ABSTRACTThe fate of mature Acacia tortilis pods on the tree and ground and A. nilotica pods on the ground were investigated at a site in South Africa. Pods on Acacia trees were browsed only by giraffe whereas pods on the ground were browsed by kudu, impala, steenbok and duiker. In the absence of giraffe most A. tortilis pods fell from the tree to the ground. When giraffe were present they consumed most A. tortilis pods at tree level. Bruchids infested 21.6–54.0% of seeds within pods on the tree. Once fallen, in the absence of browsing ungulates, A. tortilis and A. nilotica pod and seed disappearance could be attributed to burial by termites and ants, seed consumption by rodents and to decomposition; when browsing ungulates were present they consumed most pods on the ground. Between 20.0–47.6% of A. tortilis and 31.0–58.0% of A. nilotica seeds on the ground were infested by bruchids. Ungulate browsing had no effect on bruchid infestation of seeds. This study exemplifies the importance of browsing ungulates as consumers of Acacia pods. Although survival of A. tortilis and A. nilotica seeds was greatest in the absence of browsing ungulates the survival of seeds following pod consumption by ungulates is unknown.

Large African herbivores, bruchid beetles and their interactions with Acacia seeds.

This study investigated the interactions of large African herbivores and bruchid seed beetles with Acacia seeds. The germination of bruchid-infested and uninfested seeds was compaed. The effects of pod consumption by large herbivores on bruchid infestation and seed germination was also assessed. Bruchid-infested seeds did germinate, and the germination of bruchid-infested and uninfested A. tortilis, A. nilotica and A. hebeclade seeds did not differ. Pod ingestion by large herbivores lowered the bruchid infestation of consumed and defaecated seeds compared to uningested seeds. Uninfested, ingested and voided A. tortilis seeds germinated seeds. Furthermore, infested A. tortilis seeds egested by giraffe, kudu and ostrich germinated better than infested, uningested seeds. Pod ingestion by large herbivores may reduce bruchid infestation, increase Acacia seed germination and therefore increase potential Acacia seedling recruitment.

Control of Acanthoscelides obtectus Say (Coleoptera: Bruchidae) in Phaseolus vulgaris L. seed stored on small farms—I. Evaluation of damage

Abstract On-farm experiments were carried out in Darien (Valle de Cauca), Colombia, South America on stored beans (Phaseolus vulgaris L.) to evaluate the effectiveness of post-harvest treatments designed for the control of Acanthoscelides obtectus Say and adoptability by small farmers. Three treatments effectively reduced A. obtectus damage below the economic threshold (4% damaged grains) determined in this study. Vegetable oil (5 ml/kg) reduced emergence and prevented reproduction of bruchids for 8 months after harvest. Kitchen ash (20% by weight) controlled bruchid reproduction throughout the 39-week storage period. Black pepper controlled reproduction under heavy artificial bruchid infestation. The potential for small-farmer adoption of these and less successful treatments is evaluated.

Effect at some plant materials on progeny development in Callosobruchus maculatus F. in established infestations on cowpea grain at Sarnaru, Nigeria

In tests of efficacy of various plant materials for control of the bruchid, Callosobruchus maculatus Fabricus, on Cowpea at Samaru, it was found that groundnut and palm oils but not chilli pepper powder nor ash of pawpaw stem adequately protected previously uninfested cowpea from attack by the bruchid. The oils applied at 10 ml/kg seed controlled fresh bruchid infestations of up to three days old but five days or more. Adult progeny emergence was suppressed by 99.1 and 97.8% with groundnut oil by 99.6 and 98.6% with palm oil when applied at five and seven days after introducing the insects on grain, respectively. Cowpea seed germination was impaired over the control by 51.3 – 59.7% and 12.1-13.6%with groundnut and palm oils, respectively.

Resistance of faba bean, Vicia faba, to Bruchus dentipes Baudi (Coleoptera: Bruchidae)

AbstractField screening experiments for resistance of faba bean (Vicia faba) to Bruchus dentipes Baudi in Syria between 1982 and 1985 involved about 1000 accessions and indicated that only phenological resistance was present. Two accessions were chosen, on the basis of seed infestation with larvae, for further study. The two accessions (BPL33 and ILB1814) were tested against natural infestations as well as under four levels of bruchid infestation and at two different times of release of adults. BPL 33 maintained its resistance (about 50%) in relation to ILB1814 under these different conditions, except when adults were released at a time when both accessions carried pods simultaneously. This confirms that the resistance of BPL33 was phenological, related to late flowering and late pod setting. An intergrated control approach is there fore suggested.

Preferential infestation of fruits within theMedicago truncatula ? M. littoralis (Leguminosae) complex by the bean weevilBruchidius bimaculatus

The bean weevilBruchidius bimaculatus was found in fruits of 68 of 217 populations of theMedicago truncatula — M. littoralis complex of Israel, Greece, Italy and Spain. Infestation was higher in fruits of somewhat larger than mean size, and in the more pubescent and tightly coiled fruits. Bean weevil size proved to be independent of fruit size, so that the “preference” for larger fruits does not seem due to adaptation to a larger food source or a larger domicile. Fruit size has been used to delimit the host “species”M. truncatula andM. littoralis, but the character proved to be unimodal, and it is apparent that the taxonomy of the plant complex requires further clarification. Of the 11 472 fruits examined, less than 4% were infested. Given that the plants have evolved indehiscent legumes in which typically only one of the approximately six seeds survives to reproduce, and that very few seeds of a fruit are destroyed, the bruchid's infestation appears to be non-harmful, and indeed the association may be mutualistic.

Inheritance of Bruchid Resistance in Cowpea1

This study was undertaken to elucidate the nature of inheritance of resistance to bruchids [Callosobruchus maculatus. (F.)] in cowpea [Vigna unguiculata (L.) Walp.]. The parental F1, F2, and backcross populations involving three resistant and two susceptible parents were bioassayed in the laboratory for bruchid reaction on an individual plant basis. The reaction of F1 seeds was similar to that of seeds from the maternal parent, indicating that the genotype of the maternal plant controls bruchid infestation. The F2 seeds derived from F1 plants represented the true hybrid population and the mean adult emergence was similar to that of the susceptible parents, indicating complete dominance of susceptibility. No reciprocal differences were observed. The F2 plants derived from the six crosses segregated into a ratio of 15 susceptible:l resistant, indicating digenic inheritance. These results were further supported by the backcross data. The Fl plants from the backcross involving the resistant parent segregated into a 3 susceptible:l resistant ratio, whereas those involving the susceptible parent were uniformly susceptible. These data indicate that resistance to bruchids in cowpea is controlled by two recessive genes for which symbols rcml and rcm2 are being proposed.

Bruchid infestation of cowpea varieties in the field

Cowpea is one of the most widely grown leguminous crops in Africa: in Kenya it occupies over 66,000 ha and Coast Province ranks second to Eastern Province with about 5200 ha. It is an important food item consumed both as a vegetable and as a grain. Unfortunately, it suffers from both preharvest and postharvest infestations which accounts for serious losses of the crop. With the introduction to Kenya of improved varieties from IITA, Nigeria, such losses would be increased due to varying susceptibility in different pest ecosystems. The objective of this study therefore was to observe the infestation of the IITA varieties and compare them with local cowpea varieties collected from different parts of Kenya. The work was conducted at C.A.R.S., Mtwapa from 1979 to 1981 inclusive. From the study, five different bruchid species were identified as infesting cowpea varieties in the field. These were Collosobruchus rhodensienus; C. phaseoli; C. chinensis; Bruchidius atrolineatus; and C. analis; in order of decreasing abundance. Over 50% of the bruchids found in the field were C. rhodensienus while Zabrotes spp. and C. maculatus (F) were never encountered in the field. Although the IITA materials were introduced because of their yield potential, it was found that some of them were as susceptible to preharvest bruchid attack as the locally available materials. The short rains season had more bruchid infestations than the long rain season. There were also fewer eggs on pods of local varieties and fewer bruchids emerging from seeds of local as compared to IITA varieties. The results however were not significantly different. Further work should be done to establish the complex of bruchids found in stored cowpea varieties, the losses caused and control measures applicable to reduce damage.