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Seed storage is a major challenge for smallholder farmers in developing nations. Purdue Improved Crop Storage (PICS) bags effectively control the postharvest insect pests of cowpea and other crops. Farmers, encouraged by this success, have begun to expand the use of PICS bags for storing other crops. Little is known about how sorghum seed, one of these important crops, fares when stored under hermetic conditions. Accordingly, we stored sorghum seed for six months in either airtight containers (PICS bags or sealed plastic bottles) or open ones (woven polypropylene bags and open plastic bottles). Overall, sorghum seed stored in PICS bags and in sealed plastic bottles maintained its initial moisture level, germination rate and seed weight. Porous polypropylene bags and open plastic bottles lost moisture over six months. We conclude that sorghum seed can be safely stored in hermetic containers without any loss of quality for extended periods of time.

Purdue Improved Crop Storage (PICS) bags have been developed and extended as a way to address grain storage issues faced by smallholder farmers in developing nations. A hermetic technology, PICS bags reduce insect damage to grain significantly while maintaining its quality for many months or longer. Farmers with varying and often small volumes of grain at harvest, may still benefit from alternatives to PICS bags for storing their grain. We evaluated plastic bottles, which may be hermetically sealed, for storing maize grain. Clean maize grain was stored for eight months in sealed and unsealed plastic bottles with half of these bottles being infested by maize weevil (Sitophilus zemais, Motschulsky). Oxygen levels in the bottles were monitored throughout the trial and grain was assessed for moisture content, insect damage, germination rate and insect population size when the study was terminated. Sealed bottles preserved grain quality significantly better than unsealed, infested bottles and as well as non-infested unsealed containers. Plastic soda bottles can be used as hermetic containers for safely storing grain.

Cowpea production in Niger is constrained by biotic and abiotic factors that lead to lower yields and incomes for smallholder farmers. For decades now, efforts have been made to improve cowpea production, including the development and release of improved varieties that are high yielding and resistant or tolerant to pests and diseases. The present study assessed cowpea production constraints on 584 smallholders’ farms in Maradi and Zinder regions of Niger. Estimated parameters consisted of farm size, varieties used and pests and disease prevalence. We found that the average farm size for both regions was 2.10 ha. Local varieties (63%) and IT90K 372-1-2 (30.5%), an improved variety released 25 years ago, were the most-cultivated cowpea varieties. Two recently introduced varieties were planted on less than 4% of fields. Cowpea was grown in association with millet and sorghum on 96.6% of fields. Average cowpea yield for both regions was 253.4 kg ha−1. Five major insect pests and the plant parasite Striga, identified as major production constraints, were negatively correlated with cowpea yields. Diseases were significantly and negatively associated with cowpea yields. To increase cowpea productivity, there is a need to develop and/or promote adapted high-yielding varieties, and to disseminate good agricultural practices to minimize the incidence of pests and diseases.

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.

Trials of the Purdue Improved Crop Storage (PICS) bag technology for the storage of paddy rice, Oryza sativa L., were conducted in Burkina Faso, Ghana and Niger. Paddy rice naturally infested with insects, the most abundant species being Tribolium spp. and Rhizopertha dominica, was sealed in triple layer PICS bags, or in conventional woven polypropylene sacks. At the end of 7–18 months of storage in PICS bags the number of insects did not increase, the weight of 100 seeds did not change, and the proportion of damaged seeds was not different from that present when the paddy was first put into the bags. By contrast, paddy stored in the conventional way in woven polypropylene bags exhibited weight losses ranging from 3 to 8.7%. In Bolgatanga, Ghana, where paddy was stored for 18 months, germination of paddy kept in the PICS bags was comparable to that present at the beginning of the experiment. PICS bags can be used for the safe, low-cost, insecticide free storage of paddy rice.

Groundnut seeds are prone to quality deterioration and damage due to improper storage. Hermetic storage of pods offers a novel, sustainable and ecologically safe alternative over traditional methods. In this paper, we demonstrate the efficacy of triple-layer “Purdue Improved Crop Storage (PICS)” bags, (that comprises of two inner high density polyethylene bags and one outer woven polypropylene bag), for protecting pods from quality deterioration, damage by bruchids (Caryedon serratus) and aflatoxin contamination (Aspergillus flavus). Custom made triple-layer bags were used and pods (of cv ICGV 91114) were placed @ 2 kg/bag. Over four months of storage under ambient conditions, triple-layer bags supported retention of seed weight, germinability and oil content significantly better than cloth bags. Further, under both natural and artificial infestations with A. flavus, seed aflatoxins levels were lower in PICS bags compared to cloth bags. Toxin accumulation in PICS bags deliberately infested with bruchids and A. flavus was less compared to cloth bags under similar conditions. Bruchid damage to pods was less in PICS bags versus cloth bags in all cases. Our results suggest the superiority of triple-layer PICS bags over cloth bags in protecting seed viability, seed weight and oil content while safeguarding the groundnuts from bruchids and retarding toxin accumulation.

We surveyed 1293 farmers and traders in southern Niger to learn about their grain storage practices and their views on the storage pest problem. We identified the insect species found in samples obtained from 40 localities in three regions of the country. We stored 371 grain samples collected from respondents in the laboratory for seven months to allow populations of the insects present to develop and emerge and the resultant grain weight loss to be determined. The commodities most commonly stored in Niger were millet and sorghum, kept in storage on average for about 6 months by 53% and 80% of respondents respectively. When millet samples from respondents were kept in the laboratory for seven months, two pests were found, the rice moth Corcyra cephalonica Stainton, and Tribolium spp. This millet experienced a weight loss of 17.1% during seven months storage. Tribolium castaneum Herbst, Sitophilus granarius L., Cryptolestes spp, Sitotroga cerealella Oliver, Trogoderma granarium Everts, Rhyzopertha dominica F. and C. cephalonica were found in stored sorghum, which lost 10.1% weight after seven months. Eleven other grains or foods were stored by 2.9–24.4% of respondents. Recorded weight losses were 15.9% for groundnuts, 12.6% for paddy rice, 7.6% for sesame and 7.4% for maize. Seeds of Hibiscus sabdariffa L. and Bambara groundnut were essentially destroyed by bruchids during storage, mean weight losses being 83.9% and of 61.8% respectively. Most respondents took no measures to control insect pests in their stored grains. Food security and quality in Niger would be greatly improved if Africa-manufactured technology that is safe, low-cost, insecticide free, and widely available could be implemented for postharvest storage of food grains.

Purdue Improved Crop Storage Bags (PICS) bags are hermetic containers consisting of two inner layers of high-density polyethylene (HDPE) surrounded by an outer woven polypropylene bag. They have proven effective in preventing losses of stored cowpea grain to the cowpea bruchid, Callosobruchus maculatus Fabricius (Coleoptera: Chrysomelidae) and perform well with other dry grains attacked by several species of postharvest pests. We tested PICS bags against the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), a common stored grain pest. Storing rice weevil infested wheat in PICS bags arrested weevil population growth and preserved the grain well. The air surrounding infested wheat held in PICS bags had lower oxygen and higher carbon dioxide levels compared to the ambient atmosphere. Seed germination declined over time in infested PICS bags, but less so than did grain held in infested woven bags. Low-cost, durable, pesticide-free PICS technology offers an inexpensive, practical and useful way to protect wheat against rice weevil.

Hermetic storage containers are often used by farmers to protect their harvested grain from insect damage and ultimately stop insect population development. Sometimes holes in a storage container are created by insects or by accident; such holes may reduce the effectiveness of the hermetic storage unit. Using cowpea grain and the cowpea bruchid, Callosobruchus maculatus (F), we investigated the degree to which holes in a hermetic storage container wall affect the level of grain damage. When there were low numbers of holes, seed damage increased markedly with each additional hole. The grain itself contributed a barrier to oxygen diffusion through the grain mass. If holes in the container wall were patched with a single layer of HDPE film, grain damage was indistinguishable from that seen under full hermetic conditions. We provide evidence that a single layer of woven polypropylene contributes a small but measurable barrier to oxygen penetration into the container.

Dry mung bean and pigeonpea grains that had sustained some insect damage but fumigated before the start of the experiment were stored in triple-layer hermetic bags (Purdue Improved Crop Storage (PICS™ bags) or woven polypropylene (PP) bags for 6 months. Some of the bags were artificially infested with cowpea bruchid Callosobruchus maculatus (F.) (PICS1, PP1) while others were not (PICS0, PP0). In an additional trial, PP bags containing the grains were treated with Actellic Super ® dust before being artificially infested (PP1Ac). Moisture content, live adult C. maculatus count, grain damage, weight loss, and seed germination were determined on a monthly basis. At six months, moisture contents of grain stored in PICS and PP bags remained below 12%. Storage in PICS bags halted multiplication of C. maculatus , and the initial damage level and weight of grains did not change. Conversely, in the PP bags, C. maculatus populations increased massively and seed damage reached 71.8 ± 1.9%, 76.9 ± 0.4%, and 60.3 ± 0.6% corresponding to weight losses of 14.5 ± 0.1%, 16.5 ± 0.2% and 12.5 ± 0.1% in PP0, PP1 and PP1Ac, respectively, in mung beans. With the pigeonpeas, seed damage reached 55.1 ± 0.6%, 95.7 ± 0.4% and 75.8 ± 0.9%, corresponding to weight losses of 13.0% ± 0.3%, 26.2 ± 0.2% and 13.5 ± 0.1%, in PP0, PP1 and PP1Ac, respectively. PICS bags are an effective tool for preserving mung beans and pigeonpeas against C. maculatus attack, and their performance is superior to that of Actellic Super ® dust.

Pigeonpea [Cajanus cajan (L.) Millsp.] seed stored in triple layer Purdue Improved Cowpea Storage (PICS) bags for eight months retained germination and seed integrity significantly better than seed stored in traditional gunny bags. PICS bags prevented major damage caused by bruchids (Callosobruchus maculatus F.), while grain stored in gunny bags suffered severe losses. The aflatoxin levels in stored seed were low and not significantly different between the two storage systems. The levels of O2 in PICS bags artificially infested with C. maculatus dropped rapidly during the first month of storage while the levels of CO2 increased. Even in absence of bruchids (noninfested seed) PICS bags preserved seed germination for extended periods of time better than gunny bags; possibly due to the higher and more stable relative humidity inside the PICS bags. Higher seed germination would result in improved plant stands in the field and subsequent higher yields and increased productivity. Thus, PICS bags have shown potential to positively impact the economy of pigeonpea farmers in the semi-arid tropics.

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.

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

Hermetic or airtight storage of grain to suppress development of destructive populations of storage insect pests is an ancient technology that is finding modern applications in developing nations. Unprotected cowpea grain can be destroyed by unchecked growth of the bruchid, Callosobruchus maculatus (Walp). If the grain is kept in triple-layer hermetic plastic bags, losses are averted. The history, development and mode of action of triple-layer bagging for cowpea storage is reviewed here, as are lessons learned while bringing the technology to low-resource farmers in the developing nations of West and Central Africa. The success of the technology owes in part to the engagement of low resource farmers at virtually all stages of development, testing and extension of the technology.

Experiments were conducted to evaluate the performance of hermetic triple bagging using Purdue Improved Crop Storage (PICS) bags for storage of Bambara groundnut ( Vigna subterranea (L.) Verdc.). One set of experiments used grain heavily infested by Callosobruchus maculatus (F.) while a second set began with a low level infestation. Each experiment consisted of V. subterranea grain kept in four replicate 50 kg PICS bags or two replicate woven bags as controls. Two to five days after the beginning of the experiments, oxygen level inside the bags averaged about 21% (v/v) in the controls but decreased significantly in PICS bags, reaching 10% (v/v) with the heavily infested grain but falling only slightly in the lightly infested grain. After 7 months of storage, (i) the number of C. maculatus adults found between and within the grains, (ii) the 100 seed weight, (iii) the number of seed with holes, and (iv) the percentage germination of grain stored in PICS bags did not differ from what had been measured on the day that the experiment was set up. In woven bags, by contrast, there was a massive increase in C. maculatus numbers with means of 309 and 251 adults per 500 g in heavily and lightly infested grain, respectively. Grain weight losses in the woven bag controls ranged from 8 to 19% and the percentage of C. maculatus emergence holes per 100 seed increased from 51 to 135%.

When cowpea bruchid-infested cowpea grain was stored for four-plus months in Purdue Improved Cowpea Storage (PICS™) bags or in commercially-available GrainPro SuperGrain™ bags, preservation of the grain was equally good in both types of bags. In both bag types oxygen (O2) levels dropped rapidly during the first 24 h after closure, eventually reaching levels of 1–3 percent by volume (v/v). With both types of bag there was an initial rise in temperature during the first 24 h, followed by a decline, in time reaching ambient. Over the four-plus months of the experiment damage levels did not significantly increase in either type of bag while control grain kept in a conventional woven plastic bag suffered severe damage. Most of the insects found in both GrainPro and PICS bags at the end of the experiment were dead. The single layer SuperGrain™ bags showed more bruchid holes than did triple-layer PICS bags, which had no holes penetrating through both of the inner high density polyethylene (HDPE) layers, meaning that an intact O2 barrier remained in place even after the inner HDPE layer was holed. Farmers who wish to store their cowpea grain with either technology can choose between the two types of bags, taking into account price, availability and durability.

From 2007 through 2011 experiments were conducted and observations made in the West African country of Niger to address questions or concerns raised by farmers and extension workers about the Purdue Improved Cowpea Storage (PICS) triple bagging technology being widely disseminated in the country. When 518 triple bags stored by farmers in different villages across southern Niger were studied, the airspaces within the bags typically contained reduced levels of O 2 while CO 2 was increased. Bagged stored cowpea grain was much less damaged and had higher market value compared to grain for sale in the local markets. Two HDPE plastic liners rendered the system substantially airtight and improved preservation of the grain compared to a single HDPE liner. The concentrations of O 2 and CO 2 were similar along the length of the triple bag, in top, bottom and middle sections. Cowpea grain stored for 18 months in PICS bags retained high rates of germination. Briefly opening bags that had been closed for long periods did not affect the preservation of the grain. Treating the contents of the triple bag with phostoxin did not enhance preservation. Leaving the triple bag containing infested cowpea open for several days prior to closure increased the risk of blemishes or holes in the HDPE liners caused by cowpea bruchid, Callosobruchus maculatus (F.) adults.

Triple bagging technology for protecting postharvest cowpea grain from losses to the bruchid, Callosobruchus maculatus Fabricius (Coleoptera: Chrysomelidae: Bruchinae) is currently being adopted on a fairly large scale in ten West and Central African countries, including Niger. The triple bag consists of two inner high-density polyethylene bags acting as oxygen barriers, which in turn are encased in an outer woven polypropylene bag that serves primarily for mechanical strength. These hermetic bags, available in either 50 or 100 kg capacity, are called Purdue Improved Cowpea Storage (PICS) bags. Adoption of PICS technology in West and Central Africa has been driven by its effectiveness, simplicity, low cost, durability, and manufacture within the region. From surveys on adoption we discovered that farmers have begun to re-use bags they had used the previous year or even the previous two years. In the present study, we compared the performance of three different types of PICS bags: (1) new 50 kg (2) new 100 kg bags and (3) once-used 50 kg bags, all filled with naturally infested untreated cowpeas. In these PICS bags the O 2 levels within the bags initially fell to about 3 percent (v/v) while the CO 2 rose to nearly 5 percent (v/v). After five months of storage, new and used 50 kg bags and new 100 kg bags preserved the grain equally well. There were greatly reduced numbers of adults and larvae in the PICS bags versus the controls, which consisted of grain stored in single layer woven bags. The proportion of grain having C. maculatus emergence holes after five months of storage in PICS bags was little changed from that found when the grain was first put into the bags. The PICS technology is practical and useful in Sahelian conditions and can contribute to improved farmers' incomes as well as increase availability of high quality, insecticide-free cowpea grain as food.

Several technologies reputedly minimize losses of stored cowpea grain to bruchid beetles on low resource farms in Africa. Side by side comparison of these different postharvest storage methods can provide the basis for deciding which performs best. We compared six different technologies for cowpea storage: (1) grain mixed with ash; (2) mixed with sand; (3) fumigated with phostoxin; (4) admixed with the stems and leaves of Boscia senegalensis (Pers) Lam ex Poir, a potential botanical insecticide; (5) disinfested using a solar heater, and; (6) hermetically sealed in triple-layer plastic bags. Sampling was done at thirty-day intervals over five months of storage. Counts were made of (i) adult emergence holes, (ii) dead larvae and (iii) surviving bruchid larvae and adults. Controls, which consisted of infested cowpea grain stored in cloth bags, were damaged extensively. Boscia senegalensis -treated grain suffered similar severe damage. All other treatments suppressed bruchid population increases as was evident from the much lower counts of emergence holes and lower numbers of surviving or dead insects.

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

Targeting multiple digestive proteases may be more effective in insect pest control than inhibition of a single enzyme class. We therefore explored possible interactions of three antimetabolic protease inhibitors fed to cowpea bruchids in artificial diets, using a recombinant soybean cysteine protease inhibitor scN, an aspartic protease inhibitor pepstatin A, and soybean Kunitz trypsin inhibitor KI. scN and pepstatin, inhibiting major digestive cysteine and aspartic proteases, respectively, significantly prolonged the developmental time of cowpea bruchids individually. When combined, the anti-insect effect was synergistic, i.e., the toxicity of the mixture was markedly greater than that of scN or pepstatin alone. KI alone did not impact insect development even at relatively high concentrations, but its anti-insect properties became apparent when acting jointly with scN or scN plus pepstatin. Incubating KI with bruchid midgut extract showed that it was partially degraded. This instability may explain its lack of anti-insect activity. However, this proteolytic degradation was inhibited by scN and/or pepstatin. Protection of KI from proteolysis in the insect digestive tract thus could be the basis for the synergistic effect. These observations support the concept that cowpea bruchid gut proteases play a dual role; digesting protein for nutrient needs and protecting insects by inactivating dietary proteins that may otherwise be toxic. Our results also suggest that transgenic resistance strategies that involve multigene products are likely to have enhanced efficacy and durability.

Three recombinant soybean cysteine proteinase inhibitors (rSCPIs), L1, R1 and N2, were assessed for their potential to inhibit the growth and development of three major agricultural crop pests known to utilize digestive cysteine proteinases: Western corn rootworm ( Diabrotica virgifera virgifera, WCR), Colorado potato beetle ( Leptinotarsa decemlineata, CPB) and cowpea weevil ( Callosobruchus maculatus, CW). In vitro experiments showed that cysteine proteinase activities in the crude gut extracts of the WCR, CPB, and CW were inhibited to various degrees by the three rSCPIs. Of the three rSCPIs tested, N2 was most effective in inhibiting the crude gut extract of WCR, CPB, and CW (50% inhibition at 5 × 10 −8 , 5 × 10 −8 , and 3 × 10 −7 M, respectively). The L1 was the least potent of the three CPIs tested, with 50% inhibition at 5 × 10 −6 M of the crude gut extracts of WCR. Results of in vivo experiments conducted to assess the effect of the three rSCPIs on the vital growth parameters of WCR, CPB and CW were consistent with results of the in vitro experiments.

Genomics information relating to human body lice is surprisingly scarce, and this has constrained studies of their physiology, immunology and vector biology. To identify novel body louse genes, we used engorged adult lice to generate a cDNA library. Initially, 1152 clones were screened for inserts, edited for removal of vector sequences and base pairs of poor quality, and viewed for splicing variations, gene families and polymorphism. Computational methods identified 506 inferred open reading frames including the first predicted louse defensin. The inferred defensin aligns well with other insect defensins and has highly conserved cysteine residues, as are known for other defensin sequences. Two cysteine and five serine proteinases were categorized according to their inferred catalytic sites. We also discovered seven putative ubiquitin-pathway genes and four iron metabolizing deduced enzymes. Finally, glutathione-S-transferases and cytochrome P450 genes were among the detoxification enzymes found. Results from this first systematic effort to discover human body louse genes should promote further studies in Phthiraptera and lice.

This paper reviews accomplishments in cowpea cultivar and germplasm development by the Bean/Cowpea Collaborative Research Support Program (CRSP) which was funded by the United States Agency for International Development for a period of about 20 years. Drought-adapted, pest and disease resistant cultivars ‘Mouride’, ‘Melakh’ and ‘Ein El Gazal’ were developed for rainfed production in the tropical Sahelian zone of Africa. Cultivars ‘CRSP Niebe’ and ‘Lori Niebe’ which have seed and pod resistance to cowpea weevil and some disease resistance were developed for rainfed production in the tropical Savanna zone of West Africa. Cultivar ‘California Blackeye No. 27’ was developed for irrigated production in subtropical California, USA and is a semidwarf with heat tolerance and broad-based resistance to root-knot nematodes and Fusarium wilt. Various cultivars with persistent-green seed color including ‘Bettergreen’ and ‘Charleston Greenpack’ were bred for use in the food freezing industry in the USA. Germplasms were developed with unique traits including: snap-type pods, green manure/cover crop capabilities, heat tolerance during reproductive development, chilling tolerance during emergence, delayed leaf senescence as a mechanism of adaptation to mid-season drought and high grain yields, differences in stable carbon isotope discrimination, harvest index, rooting and plant water- and nutrient-relations traits, broad-based resistance to root-knot nematodes and Fusarium wilt, and resistance to flower thrips, cowpea aphid, lygus bug and cowpea weevil, and various quality traits including all-white and sweet grain. These germplasms provide a valuable resource for breeding additional cowpea cultivars for Africa and the USA.

In sub-Saharan Africa, post-harvest insect pests of cowpeas (Vigna unguiculata (L.) Walp.) degrade the nutritional quality and economic value of the grain and cause producers, in anticipation of losses during storage, to sell at harvest when the price is lowest. Principal pest is the cowpea bruchid, Callosobruchus maculatus (F.), but other bruchids cause losses as well. Beginning in the 1980s, the USAID-funded Bean/Cowpea Collaborative Research Support Program (CRSP) targeted post-harvest insect pests of cowpea as a constraint meriting an investment in research and development. Subsequently, researchers in Senegal, Cameroon, and at Purdue University, created and helped disseminate numerous simple, low cost, and environmentally friendly technologies for managing post-harvest insect pests. Technologies developed and disseminated with the help of NGOs such as World Vision International, the International Institute of Tropical Agriculture’s PRONAF program, and FAO’s Harare, Zimbabwe, office included: (1) a highly effective drum storage technology developed at ISRA, Senegal, and now widely adopted in Senegal; (2) a solar disinfestation technique developed at Purdue and at IRAD, Maroua, Cameroon, now being disseminated in many African countries; (3) an improved ash storage procedure; (4) a bagging technology utilizing triple plastic bags; (5) two cowpea cultivars expressing combined seed and pod wall resistance to cowpea bruchids, released by the Cameroon government in 1999.

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

Storing cowpeas, Vigna unguiculata (L.) Walpers, with ash to protect them against Callosobruchus maculatus (F.) is a traditional storage method in northern Cameroon. The amount of ash used and the details of the methodology (i.e. mixing vs layering, the source of ash used) varies among farmers. In experiments designed to simulate traditional ash-storage procedures, it was found that a minimum ratio of 3 parts of ash to 4 parts of cowpeas prevented population growth of C. maculatus and that a 3 cm layer of ash on top of stored seeds prevented infestation by adults.

Previous studies have shown that lectins with specificity for GlcNAc residues, when fed in the diet of the cowpea weevil,Callosobruchus maculatus, cause delays in its development. We have begun anin vivo structure activity analysis to determine what molecular features lead to maximum lectin toxicity. Although rice lectin has a four-fold greater agglutinating activity toward mammalian erythrocytes than wheat germ agglutinin (WGA), its biological activity when fed toC. maculatus is similar to WGA. Stinging nettle lectin, a poor agglutinin, isca two to four times less effective than WGA.

Wheat germ agglutinin (WGA) isolated from hexaploid wheat is made up of six isolectin dimeric forms. In order to determine if the previously observed biological activity of WGA against the cowpea weevil was due preferentially to particular isolectins, we isolated each of the three isolectin homodimers and bioassayed them in an artificial seed bioassay. We show that each of the isolectins is equally detrimental to the growth and development of the cowpea weevil. Hence, any of the three genes for WGA isolectins could, in principle, be transferred into cowpea to confer bruchid resistance.

By means of alumina absorption and reversed phase high performance liquid chromatography with electrochemical detection, N-acetyldopamine (NADA) was shown to be present in cerebral ganglia from adults of the cockroach, Periplaneta americana, and several other species of insects, but with the exception of cuticle and tracheae, non-nervous tissues contained little, if any, of the substance. In P. americana, 24 hr pretreatment with reserpine caused nearly complete depletion of brain NADA, but failed to affect NADA levels in tracheal tissue. Pretreatment of the cockroaches with l-DOPA, a precursor of dopamine, increased brain NADA levels more than two-fold.

A major digestive proteinase in the guts of larvae of biotype D of Mayetiola destructor is a chymotrypsin-like serine proteinase which can hydrolyze [3H]alpha-casein and benzoyl-l-tyrosine ethyl ester (BTEE). Hydrolysis of protein and ester by the gut proteinase were blocked by diisopropyl fluorophosphate (DFP) and inhibited by l-1-tosylamide-2-phenylethyl chloromethyl ketone (TPCK). Optimum pH for hydrolysis of BTEE by gut proteinase is 7.8. Hydrolysis of [3H]alpha-casein by gut proteinase reaches a maximum at pH 8.4 and then maintains a plateau until pH 10.8. Proteolytic activity is located extracellularly in the lumen contents of the gut. The nature of proteolytic activity appears to be consistent in all larval stages examined. The Bowman-Birk inhibitor (BBI) from soybeans is a strong inhibitor of the proteolytic and esterolytic activities of the gut proteinase. These results are discussed in the context of the potential application of naturally occurring proteinase inhibitors as engineered host plant defences against larvae of the Hessian fly.

1. 1. Liquid chromatography with electrochemical detection was used to determine concentrations of dopamine, N -acetyldopamine, 5-hydroxytryptamine, and N -acetyl-5-hydroxytryptamine in cerebral ganglion of the American cockroach, Periplaneta americana . 2. 2. Neuroactive drugs were injected into the cockroaches and their effects on biogenic amine levels in cerebral ganglion assessed. Drugs tested included α-methyltyrosine, p -chlorophenylalanine methyl ester, D ( + )-amphetamine, reserpine, pargyline, harmaline, and the formamidine pesticides chlordimeform, N -demethylchlordimeform, and N , N -didemethylchlordimeform. 3. 3. Although N -acetyldopamine was easily demonstrable in P. americana cerebral ganglion, N -acetyl-5-hydroxytryptamine could not be detected in cerebral ganglion from normal animals. However, when cerebral ganglia were incubated with 5-hydroxytryptophan or 5-hydroxytryptamine in vitro , a peak with the low oxidation potential and retention time of N -acetyl-5-hydroxytryptamine appeared. 4. 4. p -Chlorophenylalanine methyl ester and α-methyltyrosine, which have dramatic effects on the levels of 5-hydroxytryptamine and catecholamines respectively in mammalian brain, failed to significantly affect the levels of 5-hydroxytryptamine and dopamine in cerebral ganglia from cockroaches pretreated with the drugs. 5. 5. Two possible products of monoamine oxidase activity, dihydroxyphenylacetic acid and 5-hydroxy-indoleacetic acid, were not detected in cerebral ganglion from P. americana . 6. 6. Results of the present study do not support the hypotheses that either MAO inhibition or N -acetyl-transferase inhibition are important modes of insecticidal action of the formamidine pesticides.

1. 1. The pharmacology of adult Phormia regina (Meigen) feeding behavior was explored by injecting candidate drugs into starved blowflies and then determining their responsiveness to aqueous sucrose, via the proboscis extension reflex. 2. 2. d -Amphetamine caused responsiveness to fall dramatically, while related drugs and biogenic amines had varying effects. 3. 3. When d -amphetamine-treated flies were fed 1 M sucrose, they consumed significantly more than control flies. 4. 4. Electrophysiological studies demonstrated that the responses of tarsal sugar receptor neurons to aqueous sucrose were not significantly altered by d -amphetamine. 5. 5. These observations are compatible with our hypothesis that octopamine positively modulates blowfly feeding behavior and suggest that other aromatic biogenic amines affect feeding behavior in this insect.