Search

The severity of postharvest losses varies considerably depending on storage method and prevalence of storage insect pests known to bore into storage bags. Polypropylene (PP) bags used by smallholder farmers in Nigeria do not provide effective protection for stored produce due to insect boring activities. Deltamethrin incorporated polypropylene, ZeroFly® (ZF) and ZeroFly® Hermetic Storage Bags are technologies with potential to improve protection of stored food commodities against insect attack. Therefore, a 12-month study was conducted in Ibadan, Nigeria to determine the suitability and potential of combined postharvest bag technologies involving ZeroFly® (hermetic and non-hermetic) bags for smallholder farmers when exposed to Sitophilus zeamais and Prostephanus truncatus infestation pressure. Cleaned but un-fumigated 50-kg lots of maize were used to fill bags in each of the following 8 treatments - PP and ZF bags alone, diatomaceous earth-treated maize in PP and ZF bags, single and double hermetic liners in ZF bags, single hermetic liner in PP bags and lastly PICS bags. Results obtained over a 12-month period showed infestation by S. zeamais, Tribolium castaneum, Cryptolestes ferrugineus and Liposcelis spp and abundance of insect increased with storage period in PP and ZF bags without liner. The percentages of insect damaged kernels by number (IDK) were higher in PP and ZF bags without liner and were 5.4 and 16.9%, respectively; in ZeroFly bags with hermetic liners, these values were ~ 0.5%. The PP and ZF bags without liner also had higher weight loss values of 1.4 and 6.7%, respectively compared with ZeroFly bags with hermetic liners and PICS bags which had a relatively lower weight loss of ≤0.2%. These results indicate that the ZeroFly Hermetic bag mitigates insect infestations, thereby offering a suitable alternative towards achieving significant reduction in postharvest losses during storage. [ABSTRACT FROM AUTHOR]

Insect mandibles are most frequently encountered fragments in processed foods. Thanks to their sclerotised and darkly pigmented nature, they usually remain intact in foods and are relatively easily detectable. Moreover, because of their complexity and variety of shapes, stored product beetle mandibles may be useful in species determination. The present work deals with a comparative morphology of two stored product bostrichid beetles, Rhyzopertha dominica and Prostephanus truncatus. The mandibles were studied using by light and scanning electron microscopy and their morphological details, overall appearance and size are provided. [ABSTRACT FROM AUTHOR]

A study on AgroZ airtight bag was conducted against two major storage insects under simulated farmers' storage practice. Two (2) lots of 50kg white maize of Pioneer variety were put into AgroZ bag and polypropylene woven bag to serve as a control. Four replications of each bag type were used. In each bag, 50 adults of unsexed larger grain borer, Prostephanus truncatus, and maize weevil, Sitophilus zeamais, each were introduced. AgroZ bag had one liner placed inside polypropylene bag to provide support and handling convenience. Each liner had been tested for air tightness before use. The AgroZ bags were securely tied to ensure airtightness thus leading to a hermetic environment. The bags were then randomly placed in a barn on pallets in a randomised complete design (RCD). Sampling was done every 4 weeks up to 24 weeks. A 500g sample was initially taken using a compartmented long spear probe from each bag for baseline data, and subsequent ones at 4, 8, 12, 20 and 24 weeks. Repeated sampling from the same storage device reflected farmer practices of opening the device at regular intervals to draw grain for use as household food. Gas analysis in AgroZ bags showed oxygen level dropping rapidly to 7% within 4 weeks and later increased gradually to 10% at 12 weeks. Conversely, carbon dioxide level increased sharply to 10% and declined gradually to 9% over the same period. The number of insects and percentage damaged grains between AgroZ bag and polypropylene bag significantly differed from 12th week to 24th week. AgroZ bag outperformed the polypropylene bag commonly used by farmers and conveniently protected maize from insect infestation within the 6-month storage period. [ABSTRACT FROM AUTHOR]

Hermetic storage technology using plastic liners is threatened by the boring action of Prostephanus truncatus Horn. (Coleoptera: Bostrichidae), a major insect pest of stored maize in sub-Saharan Africa. We investigated the performance of four brands of hermetic storage bags against adult P. truncatus in maize stored for 90 d under simulated resident and incoming infestation. Five treatments were used: four hermetic bag brands; SuperGrain Bag (SGB) IV-R, SGB Farm, Purdue Improved Crop Storage (PICS) bag, and Kuraray bag; and an ordinary plastic bag; each containing 50 kg of shelled maize. Two modes of insect infestation were used whereby 50 adult insects were introduced inside and outside the hermetic bags to simulate resident and incoming insect infestations, respectively. Parameters measured included carbon dioxide–oxygen levels, live adult P. truncatus numbers, grain moisture content, grain damage and weight loss, germination, and number of insect-induced perforations on plastic liners. Externally infested bags had no insect activity; all the introduced insects died of starvation. Internally infested bags were all perforated. The ordinary plastic liner was severely perforated with 151 insect-induced holes compared to hermetic plastic liners (<40 holes). There was no live adult insect infestation in grain samples collected using double-tube multi-slotted sampling probes inserted vertically several times. However, live adult insects were present in the bottom grain layer (0.05 m) of all plastic liners. There were no significant differences between hermetic bags regardless of mode of infestation for all parameters assessed. The results show that the tested hermetic bags are equally susceptible to perforations by resident P. truncatus. [ABSTRACT FROM AUTHOR]

This study evaluated the potential of mass trapping to reduce Prostephanus truncatus population numbers in granaries and hence its possible utilisation as pest management tool. Universal moth traps (Uni-traps) were used to trap the pest and its predator, Teretrius nigrescens Lewis (Coleoptera: Histeridae), in granaries of small-scale farmers in three villages of the Gaza Province of Mozambique during the maize storage period of August 2013 to January 2014. Five granaries were selected in each village. Two baited pheromone traps were set up adjacent to each of three of these granaries. The other two granaries were used as controls, without traps. Numbers of both the pest and its predator were monitored in these traps as well as in stored maize ears inside the granaries for a 6-month period. Meannumbers and densities of P. truncatus, the percentage damaged maize kernels and maize kernel weight loss in granaries with and without traps were compared by means of t-tests. The Cohen's standard of effect size was applied to measure the magnitude of differences between studied variables. An average of 1272 individuals of P. truncatus was caught per trap. Mean densities of P. truncatus recorded per maize ear in granaries with traps were lower (27 individuals/ear) than of those without traps (129 individuals/ear). Mean numbers of T. nigrescens per trap followed similar patterns between granaries with and without traps. The percentage of damaged maize kernels was higher (62 %) in granaries without traps than in those with traps (22 %). Highly significant negative correlations were found between mean numbers of P. truncatus caught in traps and mean infestation in maize ears inside granaries. These findings indicate that mass trapping holds potential for control of P. truncatus in granaries of small-scale farmers. [ABSTRACT FROM AUTHOR]

Phosphine is the most widely used fumigant for stored grain insect pests, and resistance to phosphine has evolved in several species worldwide. This study was designed to determine the presence of phosphine resistance in 34 populations of Rhyzopertha dominica (F.) collected from the United States and Canada. Adult R. dominica were sampled and subjected to a discriminatory dose toxicity assay of exposure to 20 ppm of phosphine for 20 h of exposure to distinguish a susceptible R. dominica adult by death from a resistant beetle that survives the treatment. All but two of the 34 geographic populations surveyed had some beetles that were resistant to phosphine, and the frequency of resistance varied from 97% in a population from Parlier, California to 0% in beetles from both Carnduff, Saskatchewan and Starbuck, Manitoba. Probit analyses of dose-mortality bioassays with beetles from a laboratorysusceptible strain and those from five of the populations sampled were used to calculate resistance ratio factors (RRs) based on the ratio of LC50 (estimate for the concentration to kill 50% of a test group) in the sampled population to the LC50 for the susceptible strain. The highest RR for the five resistant populations was nearly 596-fold in beetles from Belle Glade, Florida, whereas the lowest RR in that group was 9-fold in Wamego, Kansas. This study revealed that phosphine resistance in R. dominica is common across North America and some populations have levels of resistance that may pose challenges for continued use of phosphine for their management. [ABSTRACT FROM AUTHOR]

Copyright of Zemdirbyste-Agriculture is the property of Lithuanian Research Centre for Agriculture & Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recent research in Ghana has demonstrated the effectiveness of an isolate ofB. bassiana,sensu lato(IMI 389521) from the U.K. against the larger grain borerProstephanus truncatus(Horn) (Coleoptera: Bostrichidae), a major pest of stored maize. To determine whether this isolate is effective on immature stages ofP. truncatus, a laboratory study of the response of immature stages (egg, larvae and pupae) ofP. truncatusin maize grains to two concentrations (1 × 109and 3.16 × 109 cfu/kg maize) ofB. bassiana, IMI 389521 formulated with Entostat™ and kaolinite was undertaken. Adult emergence, per cent survival of adults that emerged and the number of larvae in each immature stage were assessed after 45 days. Apart from the egg experiment, higher numbers of adults emerged in grains containing larvae and pupae treated withB.bassianaproduct compared to the untreated maize control. This notwithstanding, survival of emerged adults ofP.truncatuswas greatly reduced inB. bassianatreatments (<10%) compared with 75–95% in the controls. Surface treatment withB. bassianaon pre-infested maize showed a significant effect on the developmental biology ofP. truncatusin Ghana. [ABSTRACT FROM AUTHOR]

Detecting sources of insects attacking grain stores can help to develop more effective pest management tools. This study considers combinations of chemical elements as intrinsic markers for tracing resource use by Prostephanus truncatus ( Horn) ( Coleoptera: Bostrichidae), a pest of stored maize ( Zea mays L., Poaceae) which occurs in natural environments where alternative hosts may support reservoirs of infestation. Prostephanus truncatus were laboratory-reared on maize or field-caught in pheromone-baited flight-traps. Beetles and hosts were screened for multiple elements using inductively coupled plasma atomic emission spectrometry (ICP-AES). For elements above detection limits, we tested relationships between determinations for various host plants, and for beetles according to environment where captured. An alternative host, Spondias purpurea L. ( Anacardiaceae), contained more Al, B, Ca, Cu, Fe, Mg, Si, and Sr than maize, and less P and Zn. Elemental profiles of beetles were associated with environment, with significantly lower Al, Ca, Cu, Cr, Fe, P, S, Si, Sr, Ti, and Zn determinations in maize-reared beetles than in beetles captured in agricultural or natural environments. Additionally, Al, Ba, K, P, Sr, and Ti determinations of field beetles captured in agricultural vs. natural environments were significantly different. This suggests Al, Sr, and Ti as candidate markers for environment, and possibly others as elemental concentrations (except B, Ba, Ni, and P) were significantly different in comparisons of all field-collected vs. maize-reared beetles. We present a robust practical solution which successfully identified combinations of elemental markers for remotely tracing resource use and dispersal by P. truncatus. We discuss the application of chemical characterisation for identifying intrinsic markers of pests, particularly species with alternative hosts. We discuss how to manage the low replication and unbalanced sample sizes inherent in insect elemental screening, particularly when rarer elements are potential markers. [ABSTRACT FROM AUTHOR]

Many insects show a greater attraction to multimodal cues, e.g. odour and colour combined, than to either cue alone. Despite the potential to apply the knowledge to improve control strategies, studies of multiple stimuli have not been undertaken for stored product pest insects. We tested orientation towards a food odour (crushed white maize) in combination with a colour cue (coloured paper with different surface spectral reflectance properties) in three storage pest beetle species, usingmotion tracking to monitor their behaviour. While themaizeweevil, Sitophilus zeamais (Motsch.), showed attraction to both odour and colour stimuli, particularly to both cues in combination, this was not observed in the bostrichid pests Rhyzopertha dominica (F.) (lesser grain borer) or Prostephanus truncatus (Horn) (larger grain borer). The yellow stimulus was particularly attractive to S. zeamais, and control experiments showed that this was neither a result of the insects moving towards darker-coloured areas of the arena, nor their being repelled by optical brighteners in white paper. Visual stimuli may play a role in location of host material by S. zeamais, and can be used to inform trap design for the control or monitoring of maize weevils. The lack of visual responses by the two grain borers is likely to relate to their different host-seeking behaviours and ecological background, which should be taken into account when devising control methods. [ABSTRACT FROM AUTHOR]

The preference of cassava as a major host by Prostephanus truncatus Horn is a major constraint to ample production of cassava, Manihot esculenta Crantz and storage. This study analyzed the nutritional and secondary metabolite compositions in 15 cassava varieties, evaluated levels of damage and reproduction by P. truncatus, and assessed their resistance to attack. One hundred grams of dried cassava chips in 250-ml Kilner jars were infested with 10 adult larger grain borerof 0-10 days old and held for 3 months. The nutritional and secondary metabolites compositions of the dry cassava chips were determined using the method of Association of Analytical Chemists . Chip perforation rates in the cassava varieties ranged from 17.7 to 71.6%. The weight of cassava powder varied by about threefold. The final number of larger grain borer in the cassava varieties varied by about sixfold with 63 in 01/0040 and 379 in 01/1368. Hydrocyanic acid content content varied by over 10-fold and correlated negatively with number of larger grain borer. Flavonoid content varied by ∼10%. Tannins and saponin content of the cassava negatively correlated with number of adult P. truncatus. The cassava varieties 95/0166, 92/0326, 01/0040, 05/0024, and 34 91934 had selection index <0.8 and were classified as resistant to larger grain borer damage, while others with selection index >0.8 were classified as susceptible. The resistance to high damage in the resistant varieties was conferred by secondary metabolites such as tannins, saponins, alkaloids, and hydrocyanic acid content. The genetic variation in cassava varieties could be explored to breed resistant cassava varieties for use in larger grain borer-endemic areas. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is a staple crop used for subsistence by smallholder farmers around the world, who usually store grain for gradual use. During the course of storage, losses due to storage pests often reach 20%. Over three cycles of recurrent selection, population improvement to develop sources of resistance to the larger grain borer (Prostephanus truncates) and the maize weevil (Sitophilus zeamais) resulted in a new population called Population 84 (P84). The objective of this study was to evaluate the biophysical, phytochemical, and nutraceutical profile changes in P84 derived from three cycles of selection for resistance. Insect resistance parameters were evaluated using bioassay and biophysical, phytochemical, and nutraceutical parameters. Resistance to storage pests increased by two- to threefold after three cycles of selection for maize weevil and larger grain borer, respectively. The major factors related to enhanced resistance are kernel hardness (10% increase) and proportion of pericarp (68% increase) in the kernel. Comparing the phytochemical composition of the pericarp cell wall before and after selection revealed an elevated level of cell wall-bound components (42% increase), including ferulic and diferulic acids (14% and twofold increase, respectively). Increases of 18% in free phenolic acid were found in the endosperm. A significant association between insect resistance with antioxidant activity (r > 0.75) establishes the possibility of seeking increased nutrients beneficial for human health in the same maize germplasm selected for increased insect resistance and stemming from the same compounds. Population 84 is a good source for resistance to postharvest pests with enhanced nutraceutical properties. [ABSTRACT FROM AUTHOR]

Spinetoram and spinosad have been evaluated against certain stored-product insect pests with success but there are no data available on the comparison of the efficacy of these two novel compounds in stored grains. Thus, laboratory bioassays were conducted to compare spinetoram and spinosad as grain protectants against Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae) adults, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) adults, and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) adults and larvae. Factors such as treatment (1 ppm spinetoram, 1 ppm spinosad, 0.1 ppm spinetoram + 0.9 ppm spinosad, 0.5 ppm spinetoram + 0.5 ppm spinosad, and 0.9 ppm spinetoram + 0.1 ppm spinosad), exposure interval (1, 2, 7, and 14 days), temperature (20, 25, and 30 °C), and commodity (barley, maize, rye, and wheat) were evaluated. Progeny production was assessed after 60 days of exposure. Concerning temperatures, for P. truncatus adults, after 14 days of exposure, all adults were dead in treatments except of the case of spinosad alone at 20 °C. Offspring emergence was completely suppressed in all treatments at 20 and 25 °C. For R. dominica adults, after 7 days of exposure, the overall mortality ranged from 92.8 to 100 %. After 14 days of exposure, all adults were dead in all treatments of the combined use of spinetoram and spinosad at 25 and 30 °C. Progeny production was completely suppressed in all treatments at 30 °C. For S. oryzae adults, after 7 days of exposure, all S. oryzae were died at 25 and 30 °C in all treatments except in the case of spinosad alone. Offspring emergence was very low in all treatments and temperatures except in the case of spinosad alone at 30 °C. For T. confusum adults, after 1, 2, and 7 days of exposure, the overall mortality was low in all treatments and temperatures. Concerning commodities, for R. dominica adults, after 7 and 14 days of exposure, the overall mortality was >97 %. Offspring emergence was very low in all commodities. For S. oryzae adults, after 7 and 14 days of exposure, the overall mortality was increased exceeding 91 % except in the case of spinosad alone 7 days after exposure in barley. Progeny production was high in barley and rye in all treatments. For T. confusum adults, after 7 and 14 days, the overall mortality was low in barley, rye, and wheat. No offspring emergence was recorded in all treatments and commodities. For T. confusum larvae, after 14 days of exposure mortality was further increased, but did not reach 100 % for any of the combinations tested. The results of the present study suggest that the simultaneous application of spinetoram and spinosad was generally equally effective with the use of either spinosad or spinetoram alone. Furthermore, the increase of dose of either compound resulted in the same mortality levels. Thus, no benefits were achieved when spinetoram and spinosad were used simultaneously on grains, regardless of the proportion of each ingredient. These issues should be seriously considered when control measures against stored-product insects are designed. [ABSTRACT FROM AUTHOR]

Previous studies with Oriental Fruit Moth (OFM, Grapholita molesta) and Heliothis virescens males flying upwind along a pheromone plume showed that they increased their upwind flight speed as they flew higher above striped floor patterns and, for OFM, to a similar degree over dotted floor patterns. This response pattern has been demonstrated in another moth species, Epiphyas postvittana and in a beetle, Prostephanus truncatus. In all cases the role played by the change in angular size of the wind tunnel's ventral floor pattern was not assessed. In the present study we specifically addressed this question with a systematic examination of moths' flight control over different sizes of transverse stripes and dot patterns ranging down by halves from 5 to 0.625 cm and a blank white floor as a control, and showed that OFM males fly faster upwind and along their flight paths over floor patterns of decreasing size. Increased speeds over striped patterns were evident as stripe width decreased below 2.5 cm, whereas moths did not increase their flight speed over dot patterns until dot size had decreased to less than 1.25 cm. Another flight component that the moths can actively control, their course angles, was unchanged above both patterns, except for moths flying over 5 cm stripes. Turning frequency and interturn distances were mostly unchanged or offset each other, negating any effects on upwind progress. As in an earlier study examining flight speeds at three heights above floor patterns of three densities, the moths' changes in speed appear to be exclusively affected by changes in their orthokinetic response to the size of the floor pattern objects. [ABSTRACT FROM AUTHOR]

The bioactivity of powder from the leaves ofAristolochia ringens, Dalbergia saxatilis, Dioclea reflexa, Ocimum gratissimum, Chrysophyllum albidum, Moringa oleifera, Citrus limonandNewbouldia laeviswas tested against the larger grain borer (LGB) in maize kernels and the effect of the powder on the nutritional composition of the kernels was determined. A total of 72 glass bottles containing 100 g maize kernels was divided into four groups. In the first group of 32 glass bottles, 5 g powder of the experimental plants was admixed uniformly with the kernels (5% w/w). Ten 1–5-day-old LGB adults were introduced into each of the glass bottles. A second group of 32 glass bottles contains 100 g maize kernels admixed with the plant powder as described above, but LGB were not added. In the third group of four glass bottles, 100 g maize kernels received insects only, while in the fourth group of four glass bottles 100 g maize kernels were neither mixed with plant products nor infested with LGB. The treatments were arranged on worktables using completely randomised design and left for three months. The plant products-treated samples (insect free) were passed through a 30 mesh sieve to sieve out the powder and the clean kernels were analysed for proximate composition. The untreated maize kernel had a significantly (p < 0.05) higher % of grain weight loss (17.33), grain damage % (70.96), number (122.0) of adult LGB, weight (14.46 g) of grain dust and lower % of grain germination. The adsorption and absorption of some of the plant powder by the kernels had significant effect on the kernel composition of protein, fibre and carbohydrate, but not on moisture, dry matter and fat and ash content. Control of LGB with the powder of the test plants could be used as green insecticide for the management of LGB. [ABSTRACT FROM PUBLISHER]

In biological control, successful establishment of a natural enemy species depends on its adaptability in the introduced range including its ability to re-establish desired ecological interactions with the pest. These are affected by genetic parameters hitherto largely unresolved in biological control. The larger grain borer (LGB), Prostephanus truncatus, an invasive species from meso-America, is the most important post-harvest pest of maize in Africa. We studied the genetic structure of Teretrius nigrescens, a predatory beetle previously released for the control of the pest in Africa, to test the hypothesis that establishment patterns were a result of ecotype–environment mismatch and to follow up on our earlier reports of distinct lineages of the predator. We studied 13 populations of T. nigrescens, using 16 polymorphic microsatellite markers. Five genetic populations with a hierarchical structure and significant isolation by distance were detected. The most diverse population was found in southern Mexico, consistent with earlier lineage coexistence observations. Populations introduced to Africa maintained genetic similarity to local geographic populations of their area of origin. The more successful Benin releases were also more genetically diverse. Loss of rare alleles and a higher frequency of existing private alleles in some populations indicated population expansions following bottleneck events. Sustainable biological control should accommodate pest and natural enemy species, and monitor genetic changes associated with introduction and release. [ABSTRACT FROM PUBLISHER]

The insecticidal effects of deltamethrin, chlorpyriphos-methyl, pirimiphos-methyl, and spinosad were evaluated against adults of Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae) and larvae of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae). Spinosad was applied at 1 and 0.5 ppm, deltamethrin at 0.5 ppm, chlorpyriphos-methyl at 2.25 ppm, and pirimiphos-methyl at 4 ppm. All tests were carried out on wheat for E. kuehniella and in maize for P. truncatus, at three temperature levels, 20, 25, and 30 °C. Mortality of the exposed individuals of P. truncatus was measured after 7, 14, and 21 days of exposure, and 60 days later, the progeny production in the treated and untreated substrate was recorded. In the case of Ephestia kuehniella, mortality was assessed after 25 days. Spinosad was highly effective against P. truncatus adults, even at 0.5 ppm, but 1 ppm provided a better 'speed of kill' and a higher suppression of progeny production. Mortality of the exposed P. truncatus adults after 21 days of exposure on maize treated with 0.5 ppm of spinosad was 100 %, regardless of the temperature level tested. A complete (100 %) mortality level was also noted in the case of maize treated with deltamethrin and pirimiphos-methyl, while in the case of chlorpyriphos-methyl, mortality at the 21 day exposure ranged between 61 and 90 %. Progeny production was completely suppressed only on maize treated with deltamethrin. In contrast, pirimiphos-methyl was the most effective grain protectant for E. kuehniella, since mortality was usually <99 %. In general, for both species tested, temperature had a significant effect on mortality, but this trend was different at different insecticides. [ABSTRACT FROM AUTHOR]

Maize was artificially infested with either 10 or 25 individual Prostephanus truncatus (Horn) and Sitophilus zeamais (Motschulsky) or a mixture of both, and stored in a hermetic grain bag (HGB) or a woven polypropylene bag (WPB) for 150 days. Population growth of P. truncatus and S. zeamais during storage was low in HGB, while in WPB, the insect population increased significantly with storage duration. Mortality rate during storage was significantly higher in HGB than in WPB. After 60 days of storage, the average mortality rate of 99.50% was observed in HGB infested with 25 P. truncatus, and 100% for S. zeamais at the same infestation density after 90 days of storage. Grain losses were significantly lower in HGB compared with WPB. Less than 0.5 and 6.0% losses were obtained, respectively, for S. zeamais and P. truncatus in HGB infested with 25 individual insects after 150 days of storage, whereas losses of 19.2% (infestation with S. zeamais) and 27.1% (infestation with P. truncatus) were observed in WPB. HGB seems to be resistant to the perforation of S. zeamais, but not to P. truncatus. The moisture content of maize grains stored in HGB remained practically the same during storage, compared with the levels in WPB, which reduced with storage time. WPB could be used for maize storage, protecting it against insect infestation without the need for insecticide use. [ABSTRACT FROM PUBLISHER]

Crude powders of Azadirachta indica, Lantana camara, and Tephrosia vogelii, each at six concentrations (0.0, 2.0, 4.0, 6.0, 8.0, and 10% w/w), and Actellic SuperTM 2% dust were evaluated for repellence anti-feeding and toxicity to adult Prostephanus truncatus. Treatments were laid out in a completely randomised design with four replicates. Results showed that powders were strongly repellent (PR values 73.0-90.0%) and caused 46.2-52.2 and 69.7-85.6% reductions in grain damage and F1 progeny, respectively. Results showed that powders were weakly toxic to P. truncatus causing 40% kill 21 days after treatment compared to 100% kill by Actellic SuperTM 2% dust 5 DAT. The findings are discussed in the context of their relevance for integrated pest management options in smallholder agriculture. [ABSTRACT FROM AUTHOR]

In this article, we describe and compare two individual-based models constructed to investigate how genetic factors influence the development of phosphine resistance in lesser grain borer ( R. dominica). One model is based on the simplifying assumption that resistance is conferred by alleles at a single locus, while the other is based on the more realistic assumption that resistance is conferred by alleles at two separate loci. We simulated the population dynamic of R. dominica in the absence of phosphine fumigation, and under high and low dose phosphine treatments, and found important differences between the predictions of the two models in all three cases. In the absence of fumigation, starting from the same initial frequencies of genotypes, the two models tended to different stable frequencies, although both reached Hardy-Weinberg equilibrium. The one-locus model exaggerated the equilibrium proportion of strongly resistant beetles by 3.6 times, compared to the aggregated predictions of the two-locus model. Under a low dose treatment the one-locus model overestimated the proportion of strongly resistant individuals within the population and underestimated the total population numbers compared to the two-locus model. These results show the importance of basing resistance evolution models on realistic genetics and that using oversimplified one-locus models to develop pest control strategies runs the risk of not correctly identifying tactics to minimise the incidence of pest infestation. [ABSTRACT FROM AUTHOR]

The powders and extracts of Azadirachta indica A. Juss and Piper guineense (Schum and Thonn) seeds were bioassayed for their insecticidal potential against the lesser grain borer, Rhizopertha dominica (Fabr.) in the laboratory at 30+20C and 70+5% relative humidity. The powders were applied at rates 0.5, 1.0, 2.0 and 4.0g/20g of wheat grains. The extracts of the plants were also applied at rates 1, 2, 3 and 4%/20g of wheat grains. The parameter studies were adult mortality, adult emergence, % reduction of adult emergence and weight loss in treated wheat grains. The results obtained shows that adult mortality of R. dominica increased as concentration of powders and extracts increased. The two plants powders were able to evoked 100% mortality of adult R. dominica at rates 1.0, 2.0 and 4.0g/20g of wheat grains after 72 hours of post treatment. Adult emergence shows that more adult emerged from the control (46) which was significantly higher (P<0.05) than others. The extracts from the two plants seeds tested against R. dominica were able to caused 100% mortality of lesser grain borer within 48 hours of post treatment at all tested concentrations. There was no adult emergence of R. dominica in wheat treated with extracts compared to control (treated with solvent) which recorded 19 adult emergence and control (without solvent) which had 43 adult emergence. The extracts did not affect the weight of treated wheat grains. The results obtained from this study justified that powders and extracts of A. indica and P. guineense seeds can be used as biopesticides against R. dominica. The two plants are of medicinal values, biodegradable, readily available and poses no danger to man and other mammals. [ABSTRACT FROM AUTHOR]

Two liquid and one dry pre-commercial release spinosad formulations were evaluated at the labeled rate of 1 ppm against five stored-grain insect species on wheat, short-grain rice, long-grain rice, and maize. Except on maize, efficacy of spinosad was compared with a currently registered grain protectant, chlorpyrifos-methyl (3 ppm) plus deltamethrin (0.5 ppm). The 7- and 14-day mortalities of the lesser grain borer, Rhyzopertha dominica, were 99.0-100.0% on spinosad and chlorpyrifos-methyl plus deltamethrin-treated wheat, short-grain rice, and long-grain rice. Adult progeny of R. dominica after 42 days on these commodities decreased by 99.7-100.0% relative to progeny production on untreated wheat. Mortality and reduction in adult progeny of the rice weevil, Sitophilus oryzae, on the three commodities, and that of the maize weevil, Sitophilus zeamais, on maize and the red flour beetle, Tribolium castaneum, on wheat were 100.0% only with chlorpyrifos-methyl plus deltamethrin. The liquid spinosad formulations were most effective against the Indianmeal moth, Plodia interpunctella, on maize and wheat. Except for R. dominica, the effectiveness of spinosad on the other species varied with the formulation, exposure time, and commodity. Chlorpyrifos-methyl plus deltamethrin was effective against insect species on the commodities tested. [ABSTRACT FROM AUTHOR]

Post-harvest losses caused by the larger grain borer (LGB, Prostephanus truncatus) aggravate food insecurity among small-scale farmers. Host plant resistance is a method of LGB control which should be prioritized in order to reduce these losses. The objective of this study was to assess maize resistance to the larger grain borer and recognize some potential causes of resistance. One hundred and sixty-three (163) genotypes were tested; these included 85 hybrids, 2 checks, 6 open pollinate varieties, and 70 landraces, among them gene bank accessions. Grain biochemical content, (protein, oil and starch) and insect resistance parameters, (percentage grain damage, weight loss, flour weight, and number of emerged insects) were measured. There were significant differences ( P < 0.001) among the genotypes for all the traits measured except number of insects. The most resistant hybrids were CKPH08024, CKPH08009, CKPH08012, CKPH08014, CKP08033, CKPH08026, CKPH08014, and CKPH08003. The most resistant landrace accessions were BRAZ 2451, GUAT 1162, BRAZ 2100, and GUAN 36. The percentage weight loss was found to be the most important resistance trait for discriminating among genotypes for it had the largest canonical coefficient. Protein content had higher contribution to variation in resistance to the larger grain borer and this probably contributed to the grain hardness which is a putative trait of resistance to storage pests. The LGB-resistant germplasm could be used for the development of an integrated pest-management program against the LGB. [ABSTRACT FROM AUTHOR]

The microbial composition of the frass from maize (Zea mays) grains and seven dried root and tuber crops (R&TC) infested by Prostephanus truncatus were evaluated. Five cubes (6 cm3) of each R&TC as well as 100 g of maize grains were separately infested with 15 pairs of 1-2 day old adult LGB in 250 cm3 sized Kilner jars and incubated for 90 days at 28 ± 1°C and 79-82% RH. At 90 days post-infestation, the microbiological assay of frass from the commodities was performed. The results indicated the presence of 10 bacterial species, namely Bacillus cereus, B. macerans, Proteus mirabilis, P. morganic, P. rettgeri, Proteus sp., Pseud geniculatum, Pseud fragii, Pseud putela, Serratia marcences and six fungal species, namely Aspergillus niger, A. tamari, A. parasiticus, A. ochraceus, Fusarium compacticum and F. oxysporum. Infested cubes of M. esculenta have the highest population of adult LGB (168.3) and frass from its damaged cubes had the highest mean bacterial count of 30.0 × 107 colony forming units (CFU) and it was significantly (P < 0.05) higher than LGB infestation and bacterial infection of other R&TC. The bacterial count from the damaged commodities correlated positively and significantly (P < 0.05) with weight of frass, percentage damage and percentage weight loss. The results revealed that frass from the LGB-infested and damaged commodities were infected by bacteria and fungi. Maize grains and dried R&TC should therefore be protected from LGB infestation to avoid quantity reduction and microbial infection. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Protection Research is the property of Institute of Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effect of adult learning through an oviposition and host feeding experience was studied in two populations of Anisopteromalus calandrae (Hymenoptera: Pteromalidae), in choice and no-choice experiments in the laboratory using last instars of rice weevil, Sitophilus oryzae L., and lesser grain borer, Rhyzopertha dominica (F.), as hosts. In choice experiments, 20 wheat kernels infested by rice weevil and 20 by lesser grain borer were placed randomly in petri dish (15 by 100 mm) arenas. In no-choice experiments, 10 host-infested wheat kernels, either with rice weevils or with lesser grain borers, were mixed thoroughly in 500 g of uninfested wheat placed in a 0.945-liter glass jar (75 by 170 mm) arenas. A. calandrae females from a laboratory and field populations that were experienced with host larvae or naïve were introduced singly into each experimental arena and allowed to sting and oviposit for 24 h. An oviposition experience with rice weevil or lesser grain borer had a stronger effect on host preference in choice experiments compared with experiments with naïve wasps. Host-finding and parasitism rates were increased by prior experience with rice weevils in no-choice experiments. A. calandrae females clearly preferred rice weevil larvae for parasitization over larvae of lesser grain borer regardless of parasitoid population or prior experience. Also, A. calandrae females chose rice weevil larvae for producing female progeny and lesser grain borer for male progeny in choice experiments. The implications of the results of this study are discussed in relation to host preference and the selection of parasitoid populations for biological control programs in stored grains. [ABSTRACT FROM AUTHOR]

The soft-electron beam (low-energy electrons) and gamma-radiation sensitivities of phosphine-resistant (PHR) and -susceptible (PHS) strains of adults lesser grain borer Rhyzopertha dominica (F.) were studied, with particular reference to DNA damage assessed using single-cell electrophoresis (comet assay). Results showed that mortality in adult R. dominica varied significantly between both PHR and PHS strains. Adults of the PHR strain were found to be more tolerant toward soft-electron and gamma radiation than adults of the PHS strain. Studies on the longevity of strains showed that mean survival time and dose rate were highly correlated with both strains and treatments. Results also showed that adults of the PHR strain lived longer than adults of PHS strain for both treatments. Radiation sensitivity indices, however, decreased as radiation dose increased in both strains. Analysis of DNA damage, after 40- and 160-Gy gamma radiation, was carried Out using cells obtained from both strains. Gamma-irradiated adults of both strains showed typical DNA fragmentation, compared with cells from nonirradiated adults, which showed more intact DNA. Investigations using the comet assay showed that tail length, moment, olive-tail moment, percentage of tail DNA, and percentage of DNA damage were all greater in the PHS strain compared with the PHR strain and the control insects. Results also showed that DNA damage remained at a constant level for up to 24 h after irradiation. The results have been discussed in relation to the observed strain differences in radiation sensitivity and resistance to phosphine. [ABSTRACT FROM AUTHOR]

Wheat, Triticum aestivum L., varietal resistance to the lesser grain borer, Rhyzopertha dominica (F), was evaluated in hard spring wheat produced in 2001 and 2002 (Bozeman, Moccasin, and Huntley, MT). We tested the hypothesis that seed coat factors, not the endosperm, cause feeding resistance to R. dominica and that this resistance is genetic, not affected by agronomic conditions. Using a rapid, intensive feeding bioassay (frass production), we found, with one exception, no significant difference in resistance to R. dominica, among sound kernels of hard red wheat, comparing all locations and cultural conditions (irrigated versus dryland production). The most significantly resistant samples as indicated by lowest feeding activity (measured by lowest frass production) were 'Amidon' produced at Moccasin under dryland conditions and Amidon produced at Huntley under irrigated conditions. As with previous studies done in our laboratory, sound kernels of all hard wheat varieties from these new crop year studies (2001, 2002) were attacked. When subsamples of these varieties from the same locations and cultural conditions as the previous test were first subjected to a heavy infestation of Plodia interpunctella (Hübner) and then to the same age adult IL dominica, damage was significantly greater. Each kernel chosen for this test had been equally damaged by P. interpunctella larvae, germ consumed, endosperm not damaged, but fully exposed behind germ, no other damage. This collaborative damage caused feeding damage by R. dominica to increase 2- to 7.5-fold (as measured by R. dominica frass production). Particularly notable was 'McNeal' that switched from one of the most resistant varieties to the most fed upon, when the endosperm was exposed by P. interpunctella larvae. Therefore, we confirmed that at least one factor conferring resistance in McNeal is located in the kernel pericarp. [ABSTRACT FROM AUTHOR]

Seasonal flight activity of Rhyzopertha dominica near grain elevators and in forest habitats was monitored weekly in central Oklahoma from 2002 to 2005 using Lindgren four-unit multiple funnel traps baited with the synthetic pheromones Dominicalure-1 and Dominicalure-2. Response surface regression was used to model flight activity (R. dominica trap data) relative to weather variables (temperature, humidity, amount of rainfall, wind speed) and daylength. Overall, the results show more beetle flight activity near grain elevators than in forest sites. Among years, the earliest R. dominica flight activity was recorded from 20 to 27 March, and the yearly flight activity ended between 6 and 13 November. Seasonal flight activity patterns were similar among habitats; however, across years, the flight activity generally initiated at least 1-2 wk earlier in forest than at grain elevator sites in 2 of the 3 yr. R. dominica was most active during the warmer part of the year. No R. dominica were trapped from December through February. Approximately 80 and 86% of the variability in R. dominica trap catches were explained by weekly means of weather variables for grain storage elevators and forest sites, respectively. The weather-based flight activity models for both habitats were validated with independent data. [ABSTRACT FROM AUTHOR]

We determined that the number of insect fragments, quantified using the standard flotation method, in flour milled from wheat infested with larvae, pupae, or preemergent adults of the lesser grain borer, Rhyzopertha dominica (F.), was proportional to infestation level. Wheat infested with a single preemergent adult contributed 28 and lox as many fragments as wheat infested with a single larva or pupa, respectively. Using regression models that were developed from these data, we predicted that the maximum infestation level that would result in flour with fragment counts below the Food and Drug Administration defect action level (75 fragments/50 g of flour) was 0.95 and 1.5% (380-640 infested kernels/kg of wheat) for pupae and larvae, but it decreased to 0.05% (20 infested kernels/kg) when the grain was infested with preemergent adults. We also reexamined the accuracy and sensitivity of near-infrared spectroscopy (NIRS) for detecting insect fragments in flour by testing three different NIR spectrometers. NIRS-predicted numbers of insect fragments were correlated with the actual number of fragments. NIRS is less precise than the standard flotation method, but it is rapid, nondestructive, does not require extensive sample preparation, and could easily be automated for a more sophisticated sampling protocol for flour based on prescreening samples with NIRS followed up by use of the standard flotation method when necessary. [ABSTRACT FROM AUTHOR]

A series of experiments at 25 (±1)°C were conducted in which different application rates of diatomaceous earth (DE) formulation Protect-It at two levels of relative humidity, 40 and 55%, and at three exposure periods were evaluated for control of Rhyzopertha dominica (F). Test insects were placed in vials containing 40g of soft winter wheat mixed with 0.25, 0.50, 1.00, 1.50 and 2.00g DE kg-1. At all rates except 0.25 g kg-1, mortality was significantly different from that in the control at the relevant exposure period. After each exposure interval, dead and live insects were counted and removed, and the vial containing wheat was then returned to the appropriate humidity chamber for 8 weeks until F, adults emerged. F, progeny production was significantly different from the control group at all rates. Mortalities for 1, 2 and 3 weeks exposure were found to be 47 (±5)%. Despite the fact that mortality increased with increasing rate, total mortality was not achieved even at the highest rate of DE. F1 progeny production decreased with increasing rate for both RH conditions, and containment of population for both RH conditions was achieved at 1.00 g DE kg-1. For each exposure period, F1 progeny production of R dominica decreased with increasing rate of DE, and population suppression was achieved at 1.00 g DE kg-1 for all exposure intervals. In summary, Protect-It resulted in reduced F, adult progeny and containment of population was achieved at 1.00 g DE kg-1 at which rate mortality was 77%. [ABSTRACT FROM AUTHOR]

Intermale variation in pheromone signaling has been confirmed and quantified by measurements of pheromone produced by single adult male Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). Males varied in both the amounts of the two components of their aggregation pheromone and the ratio of one component to the other. The mean rates of production of the pheromone components TI and T2 were 1.9 and 0.5 µg/day, respectively. There were repeatable differences among males in the amounts of T2 produced and the proportion of T1 in the pheromone blend over two weeks. Of the 15 males studied, one released a large burst of pheromone in a short period, while the remainder, if they did release, did so over an extended period. This suggested that there may be two alternative release strategies and the significance of this is discussed. [ABSTRACT FROM AUTHOR]

Examines the electroantennogram and behavioral response of the larger grain borer, Prostephanus truncatus and the predatory beetle, Teretriosoma nigrescens to the borer-produced aggregation pheromone. Difference between species or sexes regarding perception thresholds; Responsiveness of truncatus to the pheromone; Response of predator to pheromone.

Investigates the release of Teretriosoma nigrescens Lewis in Togo. Decrease in number of Larger Grain Borer; Impact of the released predator on maize stores; Reduction of pest population in the habitat.