Prostephanus Truncatus Research Articles

Maize quality in markets in four West African countries

The quality of maize offered for sale in West African public markets was evaluated by analysing 281 samples collected in 24 markets in Benin, Togo, Ghana and Burkina Faso from February to March 2014. Grain moisture content ranged from 8.5 to 14.4 percent (wt/wt), while extraneous matter content ranged between 0.0 and 2.0% and the proportion of mouldy grains between 0.0 and 0.6%. Insect pest infestations were noted in about one-fourth of the samples with Sitophilus sp., Cryptolestes ferrugineus Stephens, Tribolium sp. and Prostephanus truncatus Horn found at densities varying between 0 and 2.4 individuals per 500 g of grain. Aflatoxin levels exceeding the accepted USA standard of 20 ppb were recorded in only 4.6% of the samples across the four countries. In most locations, grain moisture was within the acceptable range for aflatoxin- and insect-safe storage of maize using hermetic technology such as PICS bags.

Applying Biogeochemistry to Identify the Geographic Origins of Insects-A Model Using Prostephanus truncatus

application of geochemical screening for tracking insects and other organisms is poorly understood. We explored multi-elemental profiles of an insect pest and its food from different locations in order to identify intrinsic markers of geographic origin. ICP-AES screening was completed for soil, maize grains and Prostephanus truncatus of different geographic origin, with insects collected in the field or reared on maize under controlled conditions. Background level geochemical data are presented with concentrations of Cu, S and Sr in maize, and Al, Ba, Ca, Fe, S, Si, Sr, Ti and Zn in insects differing according to their origin, or that of their food. Cu, Fe and Zn determinations of insects were 20, 6.5 and 11.5 times the concentrations of the maize they were reared on. A Linear Discriminant Analysis (LDA) based on Al, Fe, Sr and Zn successfully assigned 78% of laboratory-reared P. truncatus and 94% of field-caught insects to their origin (68% and 75% respectively after jacknifing). There was excellent discrimination between insects reared on maize from Guanajuato and Nuevo Leon, and Guanajuato and Michoacan, good separation between Sonora and Nuevo Leon but overlap for Sonora, Guanajuato and Michoacan, and Michoacan and Nuevo Leon. The same LDA for field-caught insects gave complete separation between Michoacan and Sonora, but some overlap between Michoacan and Nuevo Leon. This robust ICP-AES technique successfully identified a combination of elements able to classify insects according to their origin. The model was restricted to elements showing a normal distribution but non-parametric tests suggest other elements may act as intrinsic markers. This shows the potential of atomic spectroscopy for remotely tracing insects and other biological materials, with applications including providing provenance data for species routinely captured for surveillance and to track natural enemies and wildlife.

Influence of Maize Grain Hardness and Phenol Content on the Resistance of Some Maize Varieties to Infestation by Larger Grain Borer, Prostephanus truncate(Horn) (Coleoptera: Bostrichidae).

The study evaluated some maize varieties for resistance to damage by Larger Grain Borer (LGB), Prostephanus truncatus and determined their grain hardness and phenol content. One maize ear of 100g from each of the maize varieties was placed in a glass bottle with perforated lid and infested with five males and five females LGB of 1-7days old. At 90 days post-infestation, the maize ears were visually rated for damage on a scale from 0-10. Data were collected on weight of grain dust, number of adult LGB, larvae, pupae and dead LGB. Percentage grain weight loss and % grain damage were calculated. Grain hardness and phenol content of the kernels were determined and correlated with grain damage indices. The number of adult LGB, adult mortality, weight of grain dust, % grain damage and % grain weight loss of the maize varieties were significantly (P < 0.05) different from each other. The % grain weight loss (38.23) in the variety White Maya was significantly (P < 0.05) higher than those in 98/SWI-Y, DMR-LSR-Y, DMRESR-Y and SUWAN-l-SR-Y. The % grain damage (30.51) in the variety TZPB-W was significantly (P< 0.05) higher than the damage (2.85) in SUWAN-l-SR-Y. Grain hardness (1.31) was significantly (P <0.05) high in DMR-LSR- Y and significantly(P<0.05) lower (0.74) in white Maya. Phenol content (24. 17) was significantly (P< 0.05) high in SUWAN-l-SR-Yand significantly (P< 0.05) lower (0.11) in ART/98/SW5-W. The varieties TZPB-W and White Maya with visual ratings (VR) of8.50 and 9.25, respectively, were highly susceptible to the borer. Solo with VR of 7.75 was susceptible. ART/98/SW5-W and ART/98/SW 1-Y were moderately resistant with VR of5.0 each. DMR-LSR- YandART/98/SW6-W were resistant with VRof3.5 each, while DMR-ESR-Y and SUWAN-l-SR-Y were highly resistant with VR of 1.5 each. The number of adult LGB correlated positively with % weight loss, % grain damage and weight of grain dust. Phenol content of grain and grain hardness index significantly (P <0.05) correlated negatively with weight of dust, % grain damage and % weight loss. The study suggested inherent biophysical (hardness) and biochemical (phenols) components that could withstand damage by LGB among the maize varieties. Grain hardness and phenol content of the maize grains acted as suppressive variables in relation to the maize damage traits.

Insecticidal Efficacy and Repellency of Oregano (Lippia palmeri) Essential Oil for Control ofSitophilus zeamaisandProstephanus truncatusin Stored Maize

Abstract. Maize, Zea mays L., is the most important crop in Mexico. The maize weevil, Sitophilus zeamais Motschulsky, and larger grain borer, Prostephanus truncatus (Horn), cause significant loss to stored maize. The insects are controlled by insecticides that are toxic to humans and pollute the environment. An alternative to control insect damage is essential oil from plants. The aim of this research was to evaluate the effect of oregano (Lippia palmeri S. Watson) oil at different concentrations on repellence, emergence, and mortality of maize weevil and larger grain borer. All maize weevils died at 48 hours, while most (92%) larger grain borer died at 72 hours with 1,000 µl/liter of oregano oil. Emergence of treated insects was significantly (p < 0.05) less than the check. The repellency index at 24 hours for larger grain borer was 0.15 at a concentration of 20 µl/liter of oregano oil. The repellency index for maize weevil was zero, indicating total repellence at 24 hours. Components of the oil were det...

Characterization of Sounds in Maize Produced by Internally Feeding Insects: Investigations to Develop Inexpensive Devices for Detection ofProstephanus truncatus(Coleoptera: Bostrichidae) andSitophilus zeamais(Coleoptera: Curculionidae) in Small-Scale Storage Facilities in Sub-Saharan Africa

Abstract Infestations by Prostephanus truncatus Horn (Coleoptera: Bostrichidae) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) are prevalent in small-scale Zea mays L. storage facilities in Tanzania and other regions of sub-Saharan Africa. It is especially difficult to detect these species' larvae, which feed unseen inside the grain kernels. An electronic device that acoustically detects and reliably indicates the presence of such larvae could assist pest managers in maintaining the quality of the stored maize. A study was conducted in a sound- and vibration-controlled environment to estimate the amplitudes and spectral ranges of signals that an inexpensive electronic system would encounter while detecting insects in maize storage facilities. Larva-infested wheat kernels from a laboratory colony of Sitophilus oryzae (L.), a species similar in size and behavior to S. zeamais, were placed in a pouch and inserted near the side or the bottom of a bag of maize. An acoustic probe was inserted in...

Anti-Nutritional Status of Uninfested and Prostephanus truncatus (Horn) (Coleptra: Bostichidae) Infested Dried Cassava Chips

This research study focus on the determination of anti-nutritional content status of the uninfested and infested dried cassava chips by Prostephanus truncatus. Prostephanus truncatus, the larger grain borer, is an alien invasive post harvest pest; with wide spread population all over cassava growing regions. After an infestation period of 10 weeks in the laboratory, proximate analysis revealed increased values for only alkaloids content in the infested dried cassava chips, while all other contents, such as hydrogen cyanide, saponin, tannin, trypsin inhibitor, oxalates and phytate had reduced values when compared to the un-infested dried cassava chips which recorded less antinutritional contents.

Monitoring the Establishment and Dispersal ofTeretrius nigrescensLewis (Coleoptera: Histeridae), a Predator ofProstephanus truncatusHorn (Coleoptera: Bostrichidae) in Manica Province, Mozambique

The larger grain borer (LGB), Prostephanus truncatus Horn (Coleoptera: Bostrichidae), was reported in Mozambique for the first time during February 2007, in the Mutarara district, Tete Province. Since then it has spread across all provinces of the country with exception of Nampula. Prostephanus truncatus causes severe damage to maize grain mostly in granaries of smallholder farmers. In Manica, 100% of grain damage and 61.5% grain weight loss have been reported while in Tete 77% grain damage and 50% weight loss were reported (Cugala et al. 2007). These data indicate that Prostephanus truncatus represents a serious risk and threat to maize storage and food security, because it reduces the storage period of maize to less than six months. The availability of maize as food is therefore seriously impacted.

Correlation of chemical compositions of cassava varieties to their resistance to Prostephanus truncatus Horn (Coleoptera: Bostrichidae).

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.

Developing and Validating Sequential Sampling Plans for Integrated Pest Management on Stored Products

This short communication intends to present some references on development and validation of sequential sampling plans to estimate pest density or classifying infestation levels with reference to an action/economic threshold for integrated pest management on stored products. Sequential sampling plans were developed and validated for Cryptolestes ferrugineus (Stephens), Prostephanus truncatus (Horn), Sitophilus zeamais Motschulsky, S. oryzae (L.) and Lasioderma serricorne (F.) infesting stored wheat, maize, rice, pet food or tobacco. The methods used were Wald’s sequential probability ratio test (SPRT), Green’s fixed precision sampling, fixed binomial sampling plan and/or Iwao’s confidence interval method. The firsts experiments, data were obtained from product samples but since 2003 the absolute samples were replaced by records obtained from traps (baited with pheromone or/and food lure). Only one Tobacco Company used economic thresholds, the other industries or the storekeepers applied an empirical action threshold (AT). Some studies considered that further work is needed to improve the management decision support. Other studies gave information about accuracy of the sampling program, helped the managers to make decisions and reduce the infestation levels to values far below injury.

BIOEFFICACY OF ZINGIBER OFFICINALE AGAINST PROSTEPHANUS TRUNCATUS HORN (COLEOPTERA: BOSTRICHIDAE) INFESTING MAIZE.

ABSTRACT Maize is an important cereal crop grown in sub-Saharan Africa however, greater part of the grains produced is destroyed in storage by Prostephanus truncatus Horn (Coleoptera: Bostrichidae). In this study, the bio-activities of Zingiber officinale rhizome (Ginger), was investigated in the laboratory against P. truncatus at different proportions (25%, 20%, 15%, 10% and 5% wt/wt) with Actellic dust insecticide as a reference insecticide. The highest proportions (25% wt/wt) of Z. officinale powder significantly reduced the survival of P. truncatus to 0% after 12 days of treatment and the LD50 of the dust was obtained as 6.72%. The oil extract of Z. officinale at different concentrations (700 µL/mL, 350 µL/mL, 175 µL/mL, 87.5 µL/mL and 44 µL/mL) and Agricombi insecticide as the reference was equally evaluated for the following: contact toxicity on adult insect by dipping, grain residual treatment, repellency effect, effect on progeny and adult emergence in treated grains and damage assessment to grains. There was no survival (0%) recorded at 700 µL/mL both in contact and residual treatment of P. truncatus. The LD50 of the oil extract was obtained as 84.78 µL/mL. Grains treated with the different concentrations of Z. officinale oil significantly repelled insects with the highest concentration of 700 µL/mL yielding 100% repellency. The least mean adult emergence of 0.0 was recorded for both concentrations of 700 µL/mL and 350 µL/mL in treated grains. Grain damage by P. truncatus was significantly reduced when treated with Powder and oil extract of Z. officinale compared to the untreated grains.

English

Laboratory studies were conducted at the University of Port Harcourt to evaluate the response of dried yam chips as a host for Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae). The test was conducted using four improved yam varieties namely; Adaka, Ame, Nwokpoko and Obiaturugo. Ten grams of each substrate of the dried yam chips were placed in plastic containers of 300 ml and each container was infested with three pairs of one to three days old P. truncatus. Data on insect developmental periods in the various dried chips, as well as the susceptibility of the substrates, weight gain on the chips and the weight of frass produced were recorded. The beetles exhibited differential levels of preference for the yam chips from different varieties. They developed better on Obiaturugo and Nwokpoko than on Adaka and Ame. The mean developmental period of P. truncatus on yam dried chips were 96.33 and 65.33 days for Obiaturugo and Nwokpoko, respectively but failed to develop on Adaka and Ame. There was significant difference (P<0.05) in weight between the amount of frass produced on Obiaturugo and that produced on the other substrates. Also, there was significant difference (P<0.05) in weight gained between Nwokpoko and the other substrates. The study has shown that of the dried chips from the four varieties of yam, only Nwokpoko and Obiaturugo were found to be possible hosts of P. truncatus and thus need protection against the pest during storage. Key words: Prostephanus truncatus, infestation, yam, chips.

Flying Slower: Floor Pattern Object Size Affects Orthokinetic Responses During Moth Flight to Sex Pheromone

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.

PICS hermetic storage bags ineffective in controlling infestations of Prostephanus truncatus and Dinoderus spp. in traditional cassava chips

Cassava chips were stored for 8 months in PICS bags, with half of the bags having a natural initial insect infestation, and the other half having this initial natural infestation augmented with 50 Prostephanus truncatus adults. Chips stored in traditional woven polypropylene bags served as controls. Oxygen levels varied during storage from 19.98 to 17.56%, 20.4 to 18.40%, and 20.24 to 19.92%, respectively, in PICS bags with augmented infestation (PICS-A), PICS bags under natural infestation levels (PICS-N) and polypropylene bags (WPP). Carbon dioxide levels varied from 0.73 to 3.90%, 0.65–3.56%, and 0.20–0.61%, respectively, in the three types of bags. P. truncatus populations were significantly higher in PICS-A reaching 98.66 ± 7.21 individuals/kg at the end of storage, compared to 92.66 ± 4.71 in PICS-N and 100.55 ± 3.56 in WPP. Dinoderus spp. density was significantly higher in WPP with 270.55 ± 20.59 individuals/kg after 8 months. The number of holes on chips and weight losses also increased with storage duration in all three treatments, but were significantly higher in WPP. Holes created by insects were noticed in PICS bags and were more important in the inner HDPE (high-density polyethylene) layer than in the outer HDPE layer. Up to 1913.00 ± 114.13 holes were observed on the inner HDPE layer of PICS bags and 1039.00 ± 29.40 in the outer HDPE layer. Hermetic storage bags prolong the storability of chips by approximately 1 month. PICS efficacy was probably affected by the large size of traditional cassava chips with large airspaces between individual chips, leading to a large oxygen store for insects which could not be used up through biotic activity, so that bags were not hermetic. In conclusion, PICS bags cannot be recommended for the storage of large sized traditional cassava chips.

Evaluation of spinetoram and spinosad for control of Prostephanus truncatus, Rhyzopertha dominica, Sitophilus oryzae, and Tribolium confusum on stored grains under laboratory tests

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.

PICS bags for post-harvest storage of maize grain in West Africa

Maize is a key food crop in West Africa, where Benin, Ghana, Burkina Faso and Nigeria account for most of the regional production. Storage pests are major constraints in the maize value chain, with losses reaching 30%. Simple, low-cost triple bagging technology (now known as PICS – Purdue Improved Crop Storage) originally developed for postharvest storage of cowpea was evaluated for applicability to maize storage. Thirteen test units employing PICS bag were set up in July and August 2012 at eleven localities in Benin, Burkina Faso and Ghana. Each trial unit consisted of 3 or 4 PICS bags of 50 kg capacity and 2 woven control bags. We used locally purchased naturally infested maize that had relatively high levels of infestation with Prostephanus truncatus Horn, Sitophilus zeamais Motschulsky, 1855 and/or Rhyzopertha dominica (F.) (seven localities) or lightly infested maize showing little or no evidence of damage (four localities). After 6.5 months of storage in PICS bags, there was 95–100% insect mortality at all sites. The percentage of damaged seeds and the 100 seeds weights in PICS bags were unchanged from what was recorded at the time the experiment was set up. Seed viability was well maintained; germination rates of seeds from the PICS bags did not differ from that observed at the beginning of the experiment. Aflatoxin tests were carried out on 245 samples, with 53% having levels above 20 ppm in both PICS and woven bags. Samples from PICS bags tended to be less contaminated than those from woven bags. PICS bags can be used for maize storage even in areas with high prevalence of P. truncatus, but storage of maize should begin soon after harvest and drying to minimize bag damage that can occur when very high numbers of P. truncatus are present.

Efficacy of Traditional and Improved Granaries in Protecting Maize from &lt;i&gt;Prostephanus truncatus&lt;/i&gt; in Small Holder Farming Storage System in Makonde District, Zimbabwe

The study was carried out in Makonde District, located 17°21' S and 30°12' E in Mashonaland West Province to assess the efficiency of improved and traditional granaries in protecting traditional and hybrid maize from <i>Prostephanus truncatus</i>. Ten farmers were randomly selected from 20 wards in the District. Multistage cluster sampling and purposive sampling techniques were used. Amongst the 10 selected farmers, 5 were using traditional granaries and the other 5 were using improved granaries. Four farmers used in the study stored a traditional maize variety (Hickory King) and six farmers stored a hybrid variety (SC 513). Demographic data on the farmers was captured on a questionnaire which was conducted at the beginning of the study. The questionnaire had information on type of storage granary, age of farmers, type of stored maize variety, amount of maize stored, major prevalent pests and grain management practices. Hybrid and traditional maize varieties stored in selected improved and traditional granaries. The maize varieties were first fumigated for a week using phosphine tablets and granaries were first disinfected using Deltamethrin (2.4% w.p) at 1.5g/l water at 20ml/m<SUP>2</SUP>. Fumigated traditional and hybrid maize were then stored in disinfected granaries. Maize grains were stored for 6 months. Traditional, intermediate traditional, intermediate improved, improved granaries had 36%, 16%, 30% and 18% utilization amongst farmers respectively. Age of farmers showed a significant influence on the type of granary used to store their grain. <i>Sitophilus zeamais, Prostephanus truncatus, Sitotroga cereallela</i> were most prevalent insect species. The relative abundance of these pests in the granaries was 100%, 70% and 85% respectively. Hybrid maize (SC 513) was re-infested with <i>Prostephanus truncatus</i> after 3 months during storage in traditional granaries. The relative abundance of pests in a granary was influenced by the farmer duration of storage and the treatment. It was concluded that traditional granaries used by farmers were found to be prone to<i> Prostephanus truncatus</i> infestation as compared to improved granaries. There was a significant difference in the variations between granary type, maize variety and levels of <i>Prostephanus truncatus</i> infestation.

Triple bag hermetic storage delivers a lethal punch to Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in stored maize

Clean shelled maize was stored in woven polypropylene (PP) or triple layer polyethylene (PICS™) bags in the presence of Prostephanus truncatus Horn (PP1; PICS1) or absence of it (PP0; PICS0) at ambient conditions for six months. Moisture content, live insect population, grain damage, weight loss, and germination were analyzed on a monthly basis. Temperature and relative humidity in both PICS- and PP-bag setups were monitored, as well as the oxygen and carbon dioxide levels in the PICS bags. Overall, maize stored in PICS bags had significantly lower (P < 0.05) moisture content than maize stored in PP bags. Storage in PICS bag slowed growth of P. truncatus populations and blocked infestation from the surrounding storage environment. On the contrary, PP bags permitted profuse build-up of insect population and cross-infestation. At six months, grain damage was 0.0%, 3.4%, 50.5% and 73.9%, corresponding to weight loss of 0.0%, 2.0%, 36.3%, and 47.7% in PICS0, PICS1, PP0 and PP1, respectively. Germination of maize stored in PP bags dropped from 91.1% to 37.0% and 12.7% in PP0 and PP1, respectively, whereas germination of maize stored in PICS bags dropped only marginally and reached 78.1% and 71.0% in PICS0 and PICS1, respectively, in six months. Without extreme loss of grain viability, a huge decrease in insect infestation, grain damage and weight loss is achieved by storing maize in PICS bag even under P. truncatus endemic conditions.

Post-harvest food losses in a maize-based farming system of semi-arid savannah area of Tanzania

An assessment of post-harvest handling practices and food losses in a maize-based farming system in semi-arid areas of Central and Northern Tanzania was carried out in 2012. Seventeen crops were mostly cultivated by the farmers in the surveyed areas; maize (32%), sunflower (16%) and pigeon peas (12%) were the most cultivated while maize was the most stored. There are at least 7 months between two harvest seasons of each crop; while farmers sold the crops soon after harvest to cater for household expenditure (54%) and school fees (38%), the market prices increased significantly (P ≤ 0.05) within six months of storage. Most processing activities (winnowing, dehulling, drying, sorting and shelling) were carried out manually, almost entirely by women, but mechanized processing for maize, sunflower, millet, and sorghum were commonly practiced. Quantitative post-harvest losses of economic importance occur in the field (15%); during processing (13–20%), and during storage (15–25%). The main storage pests responsible for the losses are larger grain borers (Prostephanus truncatus), grain weevils (Sitophilus granarius) and, the lesser grain borer (Rhyzopertha dominica). Most of the farmers considered changes in weather (40%), field damage (33%), and storage pests (16%) as the three most important factors causing poor crop yields and aggravating food losses. However, survey results suggest that the farmers' poor knowledge and skills on post-harvest management are largely responsible for the food losses. 77% of the surveyed farmers reported inadequate household foods and 41% received food aid during the previous year. Increasing farmers' technical know-how on adaptation of the farming systems to climate variability, and training on post-harvest management could reduce food losses, and improve poverty and household food security.

Molecular markers reveal narrow genetic base and culturing-associated genetic drift inTeretrius nigrescensLewis populations released for the biological control of the larger grain borer in Africa

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.

IDENTIFICATION OF MAIZE LANDRACES WITH HIGH LEVEL OF RESISTANCE TO STORAGE PESTS Sitophilus zeamais Motschulsky AND Prostephanus truncatus Horn IN LATIN AMERICA

The maize weevil (MW) (Sitophilus zeamais), and the larger grain borer (LGB) (Prostephanus truncatus) are major storage pests causing serious losses in maize (Zea mays L.) in developing countries of Latin America (LA). This study identified maize landraces with high levels of resistance to MW and LGB by screening 1171 genotypes collected from 24 LA countries in 38 sampling areas. Maize grain weight losses (GWL), total dust production (TDP) and number of adult progeny (NAP) were measured for LGB and MW attack in each genotype. Susceptibility traits to MW and LGB were related to specific geographical location. Range of resistance for MW was from 0.6 to 51 %, while for LGB from 0.1 to 66 %. Approximately 28 % of the analyzed genotypes showed high level of resistance to MW, with Antilles region offering the most resistant accessions with races of EarCar, Chande, Haitye, Nal-Tel, Tuson, and Canill. Resistance to LGB was observed in 22 % of genotypes analyzed with accessions from Southern México with races of Cónico, Nal-Tel, Vandeño, Elotes Occidentales, Cubano, Tuxpeño, and Tepecintle. Low correlation (r = 0.28; P &lt; 0.01) between maize resistance to MW and LGB indicated a divergent adaptive response of maize grain to these two pest. Geographic data showed a negative correlation between latitude and longitude with MW resistance traits being significant only for longitude (r = -0.253; P &lt; 0.05). Opposite trend of correlations, positive but not significant, was observed for LGB resistance traits. These results indicate an influence of geographic location in local varieties being selected for storage pest resistance over time. Genotypes with excellent postharvest insect resistance have now been identified for maize breeders to use in developing improved cultivars for use in LA.The maize weevil (MW) (Sitophilus zeamais), and the larger grain borer (LGB) (Prostephanus truncatus) are major storage pests causing serious losses in maize (Zea mays L.) in developing countries of Latin America (LA). This study identified maize landraces with high levels of resistance to MW and LGB by screening 1171 genotypes collected from 24 LA countries in 38 sampling areas. Maize grain weight losses (GWL), total dust production (TDP) and number of adult progeny (NAP) were measured for LGB and MW attack in each genotype. Susceptibility traits to MW and LGB were related to specific geographical location. Range of resistance for MW was from 0.6 to 51 %, while for LGB from 0.1 to 66 %. Approximately 28 % of the analyzed genotypes showed high level of resistance to MW, with Antilles region offering the most resistant accessions with races of EarCar, Chande, Haitye, Nal-Tel, Tuson, and Canill. Resistance to LGB was observed in 22 % of genotypes analyzed with accessions from Southern México with races of Cónico, Nal-Tel, Vandeño, Elotes Occidentales, Cubano, Tuxpeño, and Tepecintle. Low correlation (r = 0.28; P &lt; 0.01) between maize resistance to MW and LGB indicated a divergent adaptive response of maize grain to these two pest. Geographic data showed a negative correlation between latitude and longitude with MW resistance traits being significant only for longitude (r = -0.253; P &lt; 0.05). Opposite trend of correlations, positive but not significant, was observed for LGB resistance traits. These results indicate an influence of geographic location in local varieties being selected for storage pest resistance over time. Genotypes with excellent postharvest insect resistance have now been identified for maize breeders to use in developing improved cultivars for use in LA.