Undamaged Seeds Research Articles

Effects of position of seed perforation by cowpea weevils, Callosobruchus maculatus (F.), on viability and vigour of cowpea (Vigna unguiculata L. Walp) seed

Cowpea, Vigna unguiculata, is a high-protein legume crop that is often susceptible to pest damage. The cowpea weevil, Callosobruchus maculatus, predates on cowpea seeds in storage which renders grain unsuitable for human consumption. In the larval stage, cowpea weevils consume food reserves from the seed endosperm and may deter seed germination. The problem is more pervasive among resource-poor farmers in Sub-Saharan Africa, who grow cowpea for subsistence and keep the surplus grain for sale and use it as seed in the subsequent growing seasons. Unsuitable storage structures and ineffective methods of weevil control may increase weevil infestation of cowpea seeds in storage which constrains the production of cowpeas. The aim of the study was to determine if the position of seed perforation by cowpea weevils affects seed viability and growth of cowpea seedlings. Undamaged cowpea seeds ‘black-eyed peas’ were infested with cowpea weevils and stored for three months to allow for infestation. Thereafter, seeds with a single perforation or hole were selected from the infested seed lot and sorted into groups of damage according to the position of the hole on the seed. Five categories of potential damage were identified namely seeds with holes on the top, bottom, side, back or hilum area of the seed as presented schematically in the paper. The positions of holes on seeds served as treatments for the study and undamaged seed served as control. Data on germination and seedling height were collected and analysed statistically. Results reveal that the positions of damage on seed affects seed germination and seedling height. Seed germination on day two was significantly poorer for seeds damaged at the top, relative to both undamaged seeds and the alternative sites of damage. The results of top damaged seed being inferior than other treatments, remained consistent for germination on day seven and for seedling height at two weeks after the first emergence. Small holder farmers should therefore refrain from planting top damaged cowpea seed.

EFFECT OF MORINGA (MORINGA OLEIFERA) LEAF POWDER, NEEM (AZADIRACHTA INDICA) LEAF POWDER, AND CAMPHOR ON WEEVIL (CALLOSOBRUCHUS MACULATUS F.) IN STORED COWPEA (VIGNA UNGUICULATA (L.) WALP) SEEDS

Cowpea (Vigna unguiculata (L.) Walp.), one of the most important leguminous crops, is widely cultivated throughout the tropics, especially in the savanna regions of the world. However, its seed is attacked by several insect pests both in the field and in storage, especially the cowpea weevil. To control weevils, most farmers have adopted the use of chemical insecticides, but these insecticides come with health and environmental problems, and as a result, there is advocacy for the use of bio-pesticides in the form of tree botanicals. This study was conducted to assess the effects of neem leaf powder (NLP), moringa leaf powder (MLP), and camphor against the cowpea weevils (Callosobruchus maculatus) in a completely randomized design. Six treatments were used and allocated as T1 (control), T2 (4g of camphor), T3 (25g of NLP only), T4 (25g of MLP only) T5 (50g of NLP only) and T6 (50g of MLP). The treatments were replicated three times. The parameters studied were the numbers of damaged and undamaged seeds, the numbers of dead and live weevils, and the taste of cowpea seeds. The treatments effectively protected the cowpea seeds during the storage period of eight weeks. The preservation of cowpea seeds given by camphor was significantly different from the other treatments. However, there was no significant difference (p >0.05) between the neem and moringa leaf powders treatments. The use of moringa and neem leaf powders might be adopted by cowpea farmers in sub-Saharan Africa as alternative, cheap, and available sources of biopesticides to use as chemical insecticides. If cowpea seeds are to be stored for consumption purposes, moringa leaf powder should be used since most respondents preferred the taste of cowpea seeds treated with moringa. Additionally, the storage duration of eight weeks was too short for the experiment, so further studies can be carried out for an extended period of more than eight weeks.

Leaf‐cutting ant nests support less dense and impoverished seed assemblages in a human‐modified Caatinga dry forest

AbstractRegenerating forests make up an increasingly large portion of tropical landscapes worldwide and regeneration dynamics may be influenced by leaf‐cutting ants (LCA), which proliferate in disturbed areas and collect seeds for fungus culturing. Here, we investigate how LCA influences seed fate in human‐modified areas of Caatinga dry forest. We evaluate the seed deposition and predation on Atta opaciceps nests, foraging habitat surrounding nest and control habitat away of nest influence of 15 colonies located along a forest cover gradient during the rainy and dry seasons. For each habitat, four 50‐cm2 plots were established and all seeds on the soil surface were collected along 1 year. We recorded 13,628 seeds distributed among 47 species and 36.57% of the total seeds did not show any sign of predation. Nest mound habitats supported low‐density and species‐poor seed assemblages, which were taxonomically distinct from the control habitats. These effects only occurred in the rainy season. The proportion of undamaged seeds were similar across the habitats. While forest cover did not influence seed assemblage in terms of species richness or seed predation, it did interact with habitat type via increments in seed abundance as forest cover increased across the nests. Forest cover also affected seed composition, but only in the rainy season. These results indicate that LCA decrease seed deposition in areas under their influence, particularly on the nest mounds. As LCA profit from human disturbance in the Caatinga, their role as seed ‘sinks’ should be enhanced in disturbed Caatinga patches, particularly during the rainy season, when most of the plant recruitment occurs. Our findings reinforce the importance of LCA as drivers of forest dynamics and resilience in human‐modified landscapes.

Secondary Seed Ingestion in Snakes: Germination Frequency and Rate, Seedling Viability, and Implications for Dispersal in Nature

The importance of vertebrate animals as seed dispersers (zoochory) has received increasing attention from researchers over the past 20 years, yet one category in particular, diploendozoochory, remains understudied. As the term implies, this is a two-phase seed dispersal system whereby a secondary seed predator (carnivorous vertebrate) consumes a primary seed predator or granivore (rodent and bird) with undamaged seeds in their digestive tract (mouth, cheek pouch, crop, stomach, or other organ), which are subsequently eliminated with feces. Surprisingly, although snakes are among the most abundant predators of granivorous vertebrates, they are the least studied group insofar as our knowledge of seed rescue and secondary dispersal in a diploendozoochorous system. Here, using live snake subjects of the Sonoran Desert (one viperid and two colubrid species) and seeds of the Foothill Palo Verde (Parkinsonia microphylla), a dominant tree of the same region, we experimentally tested germination frequency and rate, and seedling viability. Specifically, to mimic rodents with seed-laden cheek pouches, we tested whether wild-collected P. microphylla seeds placed in the abdomen of thawed laboratory mice and ingested by the snakes would retain their germination viability. Second, we examined whether seeds exposed to gut transit germinated at a greater frequency and rate than the controls. While we found strong statistical support for our first hypothesis, both aspects of the second one were not significant. Accordingly, we provide an explanation for these results based on specific life-history traits (dormant and non-dormant seeds) of P. microphylla. Our study provides support for the role of snakes as important agents of seed rescue and dispersal in nature, their potential as ecosystem engineers, and crucial evidence for the investment of field-based studies on diploendozoochorous systems in deserts and other ecosystems.

Mesopredator frugivory has no effect on seed viability and emergence under experimental conditions

AbstractMembers of the orderCarnivoraare a unique and important seed disperser who consume and deposit undamaged seeds while providing regular long‐distance seed dispersal opportunities. Some members ofCarnivora, such as coyotes (Canis latrans), are undergoing range expansions which may help the plant species they consume colonize new locations or replace dispersal services provided by recently extirpated species. In this study, we evaluated aspects of the seed dispersal effectiveness of coyotes and gut passage time to determine the potential dispersal distances for three commonly consumed and commonly occurring plant species (Amelanchier alnifolia, Celtis ehrenbergiana, andJuniperus osteosperma). We also investigated the potential effects of secondary dispersal of seeds away from scats by comparing seedling emergence from whole scats to those where seeds were first removed from scats. We found that seeds generally took between 4 and 24 h to pass through the digestive tract of coyotes, which could result in regular seed dispersal up to 7 km. Gut passage through coyotes had no effect on seed viability or emergence for any of the three plant species, including that gut passage forA. alnifoliaandJ. osteospermadoes not replace cold stratification for breaking physiological dormancy. By simulating secondary dispersal, we found that 22% (±8.2%) moreC. ehrenbergianaseedlings emerged when seeds were removed from scats and those seedlings emerged 7 d earlier (±5 d) compared to seeds that remained in the coyote scat. Coyotes are effective seed dispersers, with the potential for regular long‐distance dispersal services and for providing opportunities for secondary seed dispersal, which could aid in climate migration or serve to replace extirpated dispersal mutualists.

Effect of cashew (Anacardium occidentale) nut shell stored and fresh extracts on cowpea bruchid, Callosobruchus maculatus (Fabricius.) (Coleoptera: Chrysomelidae)

Effect of cashew (Anacardium occidentale) nut shell stored and fresh extracts on cowpea bruchid, Callosobruchus maculatus (Fabricius.) (Coleoptera: Chrysomelidae)

Fire damage on seeds of Calliandra parviflora Benth. (Fabaceae), a facultative seeder in a Brazilian flooding savanna

AbstractOptimal sexual reproduction in relation to fire effects varies in Fabaceae species. Calliandra species have a large investment in reproduction. We investigated the consequences of fire during the fruiting period of Calliandra parviflora Benth., by checking fruit exposure to fire, pre‐dispersal seed predator infestation, and the effect of fruit burning on germination. We conducted this study in a floodable savanna in central Brazil, where we collected burnt and unburnt fruits. We measured the fruit and seed mass, and counted the number of damaged and undamaged seeds and live larvae per fruit. We analyzed the seed germination percentage from burnt and unburnt fruits. The burnt fruits presented greater mass than the unburnt fruits, despite their seed mass being similar. The number of damaged seeds per fruit was only slightly higher in burnt compared to unburnt fruits (p = 0.047). The number of larvae on pre‐dispersal seeds per fruit varied from 0 to 4 and did not differ between burnt and unburnt fruits. The germination percentage of unburnt fruit seeds (mean = 22 ± 17%), was significantly higher than that of burnt fruit (mean = 3.0 ± 2.0%, p < 0.001). Fire during fruiting or pre‐dispersion decreases seed germination from 22 to 3%, but it does not hurt vegetative regeneration or resprout capacity of C. parviflora, which is a facultative seeder. Hence, we suggest that C. parviflora has potential for post‐fire restoration in floodable open grassy savannas, in the ecotone between Cerrado and Pantanal, because this species may sprout quickly after first post‐fire rains.

Nysius Plebeius distant (Heteroptera: Lygaeidae; Orsillinae) feeding impacts on seed weight and germination of perilla crop

Nysius species are one of the emerging pests of perilla crop in Korea. Seed weight loss and germination of perilla seeds caused by Nysius plebeius were studied by exposing perilla seeds cv. Deulsaem to six insect infestation levels (0, 5, 10, 15, 20, and 25 individual) for 3 and 5 days in the laboratory. The seed weight loss and germination rate were significantly affected by infestation levels and feeding durations. The feeding impacts on seeds increased with increasing in bug density and duration. The higher seed weight loss, and weak germination were recorded at higher bug density (25 individuals) for longer (5 days) feeding duration. The triphenyl tetrazolium chloride, TTC, showed lower seed viability for damaged seeds than undamaged seeds. The outcomes of the study are discussed in terms of impacts of perilla seed bugs infestation, and suggest longer field exposure of perilla seeds to seed bugs may bring lower yield with poor quality of seeds and low germination potential of seeds. Future studies should examine the changes in nutrient contents of seeds after exposed to perilla seed bugs.

Consequences of tropical dry forest conversion on diaspore fate of Enterolobium contortisiliquum (Fabaceae)

Habitat conversion is one of the major threats for biodiversity conservation and viability of natural populations. Thus, habitat disturbance alters distinct ecological processes, such as plant reproductive success and diaspore fate. In this study, we determined the effects of seasonally tropical dry forests (STDFs) conversion by anthropogenic disturbance by assessing diaspore fate of Enterolobium contortisiliquum. We compared 20 adult trees present in a STDFs preserved area and 20 adult trees present in a human-converted area. In general, diaspore fates from both areas were similar, i.e., there was no difference in the reproductive success of trees in STDFs and human-converted area. Habitat disturbance did not affect the length or width of fruits; only fruit thickness was larger in trees of STDFs habitat. None of the biometric seed measures differed between different habitat conditions. Likewise, the number of undamaged seeds, aborted seeds, pre-dispersal predated seeds, and seed production were independent of habitat conditions. Besides, we did not observe any effect of habitat disturbance on germination percentage. However, seeds from preserved STDFs germinated faster than seeds from the human-converted area. Even though the effects of human-modified habitats on the diaspore fate have already been studied, tree species exhibit different responses to habitat conversion regarding seed predation, seed dispersal, seed germination, and seedling establishment. Overall, our results show that habitat disturbance does not affect the diaspore fate of E. contortisiliquum. This study also highlights the importance of remnants trees in converted landscapes as the population’s connectors which maintain plant–animal mutualistic and antagonistic interactions that mitigate the effects of habitat disturbance.

CONTROL DE GORGOJO (Sitophilus zeamais MOTSCHULSKY) CON POLVOS DE EPAZOTE (Dysphania ambrosioides (L.) MOSYAKIN & CLEMANTS) EN DIFERENTES GENOTIPOS DE MAÍZ

Durante el manejo postcosecha del maíz (Zea mays L.) se presentan pérdidas importantes por el ataque de plagas de almacén, particularmente por gorgojo (Sitophilus zeamais Motschulsky). El objetivo del presente estudio fue evaluar la efectividad del epazote (Dysphania ambrosioides) para controlar los daños por gorgojo en maíz. Semillas de 11 genotipos de maíz, nueve experimentales y dos híbridos comerciales, todos con humedad de 13 % y sin daño físico que indicara la presencia de insectos, fueron sometidos a tratamientos con polvo de epazote en cuatro concentraciones (0, 5, 7 y 10 g de epazote kg-1 de semilla) para controlar gorgojo. Se utilizó un diseño completamente al azar con arreglo factorial y tres repeticiones. La unidad experimental consistió en una caja de plástico acondicionada donde se colocaron 100 semillas, previamente pesadas, junto con 50 gorgojos jóvenes y la dosis correspondiente de polvo de epazote. Las variables registradas fueron pérdida de peso, granos dañados y sobrevivencia de insectos, todos expresados en porcentaje. Hubo diferencias entre genotipos de maíz solamente para pérdida de peso (P ≤ 0.05); todos los genotipos de maíz registraron pérdidas; sin embargo, el híbrido CLTHW14001 fue el menos afectado con 3.5 % de pérdida de peso. Las dosis de 7 y 10 g de epazote kg-1 de semilla fueron sobresalientes en las variables pérdida de peso, granos dañados y sobrevivencia de insectos, con 3.4, 12.2 y 3.5 % en promedio, respectivamente. El híbrido CLTHW14001 mostró el menor daño con la dosis de 7 g de epazote kg-1 de semilla con 0.94 % de pérdida de peso. El uso de polvo de epazote para el control de gorgojo es efectivo en concentraciones desde 7 g kg-1 de semilla. El genotipo de maíz influye en la efectividad del tratamiento.

Factors limiting the recruitment of artificial black locust forests in extremely arid environment

Afforestation is a common ecological practice for solving drought issues. However, unclear regeneration mechanisms in the context of drought jeopardize artificial forests. Sexual and asexual reproduction (seeds, seedlings and resprouts) in an artificial black locust forest on the Loess Plateau of China (LPC) were investigated to better understand the recruitment limitations of artificial forests in an extremely arid environment. This study found that the thousand kernel weight of black locust was 16.97 g (±1.19) on the LPC, which was lighter than that reported in other regions. The proportion of undamaged seeds on the trees was 83.56% (±6.29), although this value reduced to 17.47% (3.48) when the seeds fell to the litter layer and ground surface. The germination rate of undamaged seeds in the laboratory environment was 79.66% (±12.61) on average. Thus, a low seed weight will not reduce the germination rate in suitable environments but will most likely lead to reduce the ability of keeping health after the seeds drop to the litter layer. The reproduction of artificial black locust forests in the extremely arid environment was also low, with 467.86 individuals/ha on average. The quantity of sprouts of a larger size was more than that of seedlings. The results further indicated that reproduction was affected by deficiencies in water and available nutrients and competition for resources from aboveground vegetation. The disturbance intensity was good for resprouts. Seedlings and resprouts self-clumped at scales of 1–7 m and 0–4.5 m, respectively. Seedling recruitment declined near adult trees, while resprouts survived better near adult trees. We suggest that drought- and low nutrient-resistant cultivars and planting on gentle slopes should be implemented to improve recruitment in the studied forest. Moreover, asexual reproduction may be improved via forest management.

Efficiency of chemical protection of spring rape and mustard from rape blossom beetle

One of the most dangerous pests of cabbage crops which can damage plants in the budding and flowering phases in all areas of their cultivation is a rape blossom beetle (Meligethes aeneus Fabricius, 1775). The pest is widespread throughout Ukraine; it causes significant damage to the crops every year and reduces the seed yields. It should be noted that the rape blossom beetle is not new to our country and as a pest of rape and other crops from the cabbage family has been mentioned since 1845, and a detailed description of its morphology, biology and ecology can be found in the works of the nineteenth century. It is established that in the Eastern Forest-Steppe of Ukraine the first individuals of the rape blossom beetle appear on the flowering wild growing plants (first of all on dandelion and buttercup) when the average daily temperature exceeds 8 °C, it is the middle of the first decade of April and the beginning of the third decade of April. The mass emergence of the rape blossom beetles takes place when the daily average temperatures are at the range of 9–13 °C and the sum of the effective temperatures above 5 °C is at the range of 100–113 °C, it is the middle of the second decade of April and the end of the third decade of April. The females of the rape blossom beetle usually lay 2–3 eggs into one bud of spring rape or mustard. When protecting the crops from the rape blossom beetle the highest technical efficiency was noted when applying the binary mixture of the microbiological preparation Actophyte, 0.25 % of emulsion concentrate in the dose of 4.8 L/ha and systemic insecticide Biscaya, 24 % of oily dispersion (0.25 L/ha) and in 14 days after spraying it was 76.6 % on white mustard, 74.3 % on Chinese mustard and 76.2 % on spring rape. The highest growth increase in the yield capacity was observed in the same variant; for white mustard it was 0.431 t/ha, for Chinese mustard it was 0.265 t/ha and for spring rape the growth increase amounted to 0.277 t/ha. As a result of the researches it is established that the weight of 1000 healthy seeds is 2,6996 g, and the weight of the seeds damaged by the larvae of the rape blossom beetle is 0.4213 g, so it is reduced by 84.4 %. The filling of the damaged seeds is 6.8 times more, which indicates that they are smaller in diameter and frail. The undamaged seeds of spring rape contain 35.92 % of fat, and the damaged seeds contain only 17.48 %, which is 2.05 times less. The protein content in the undamaged seeds was 30.97 % and in the damaged ones it was 32.23 %, that is 1.04 times more. The germination rate of the undamaged seeds of spring rape under the laboratory conditions on the eighth day was 90.0 %, and the germination rate of the damaged ones amounted to 58.0 % and was lower by 32.0 %.

X-ray microtomography in comparison to radiographic analysis of mechanically damaged maize seeds and its effect on seed germination

Among the most relevant aspects of seed production, mechanical damage may affect seed germination and reduce health and vigor. This study introduces a noninvasive high-resolution imaging procedure for evaluating the mechanical damage to maize seeds and the effects on seed germination. Seeds with different levels of mechanical damage were evaluated using a benchtop micro-computed tomography system (micro-CT) and digital X-ray equipment. The two-dimensional transaxial, coronal and sagittal micro-CT sections were used to inspect the seed anatomy and the mechanical injuries in the internal seed tissue. Germination tests were performed using paper towel rolls (25°C for 7 days) in which the seedling length was evaluated on a daily basis, and the seedling dry biomass was measured at the seventh germination day. The micro-CT cross-sectional images allowed an efficient spatial characterization of the mechanical damage inside the seeds. On average, mechanically damaged seeds produced seedlings with a length 24% shorter and a dry biomass 65% less than that of the undamaged seeds. We concluded that the micro-CT technique provides an efficient means to inspect mechanically damaged maize seeds and allows for a reliable association with germination response.

Life history of Plodia interpunctella Hübner on sunflower seeds: Effects of seed qualitative traits and the initial seed damage

Sunflower seeds are regularly infested by Plodia interpunctella during storage. Although this pest prefers damaged seeds, in practice it can infest undamaged seeds as well. This research assessed the influence of the sunflower seed type (oil, protein for human consumption and bird-feed) and the initial seed damage during post-harvest processing (dehulled kernels, 10, 20, 30% of damaged seeds and undamaged seeds) on development of P. interpunctella (larval mortality, larval development, mean developmental duration, adult emergence and fecundity). Biochemical analysis of seeds, kernels and hulls detected the highest content of phenols in the seed and hull and tocopherols in the kernel of the oil type hybrid. The antioxidative activity was the highest in the seed, kernel and hull of the protein type for bird feed. The shortest development (39.5 days) and the highest fecundity (91.3) were on the oil type seeds, while the longest development (42.1 days) and the lowest fecundity (68.1) were on the seeds of the protein type for bird feed. The highest mortality of larvae was on the undamaged seeds of the protein type for bird feed and human consumption (21.3% and 14.0%, respectively). The type of sunflower and the level of initial damage affected larval mortality, developmental duration and fecundity. The mean developmental duration and the number of emerged adults were dependent only on the initial seed damage. Principal component analysis detected strong positive correlation between mortality and development with the tocopherol content on the undamaged seeds while fecundity was associated with the state of kernel and the amount of tannins, proteins and oil content in the seed. The undamaged seeds of the protein type for the bird feed were the least suitable for the development of this pest, while the oil type kernels were the most suitable.

Interactions between seed traits and digestive processes determine the germinability of bird-dispersed seeds.

Waterbirds disperse a wide range of plant seeds via their guts, promoting biotic connectivity between isolated habitat patches. However, the intensity of digestive forces encountered by seeds, and therefore their potential to survive digestive tract passage, varies within and between waterbird species. Here, we investigate under controlled conditions how the interaction between seed traits and digestive strategies affect the germinability of seeds following waterbird-mediated dispersal. We exposed seeds of 30 wetland plant species to the main digestive processes in the dabbling duck digestive system: mechanical, chemical and intestinal digestion. These were simulated by 1) a pressure test and scarification treatment, 2) incubation in simulated gastric juice, and 3) incubation in intestinal contents of culled mallards (Anas platyrhynchos). We evaluated their separate and combined effects on seed germination, and identified the role of seed size and seed coat traits in resisting the digestive forces. Seeds were generally resistant to separate digestive processes, but highly sensitive to a combination. Resistance to mechanical break-down was reduced by up to 80% by chemical pre-treatment, especially for seeds with permeable coats. Scarified seeds were 12–17% more vulnerable to chemical and intestinal digestive processes than undamaged seeds. Large seeds and seeds with thin, permeable coats were particularly sensitive to chemical and intestinal digestion. These results indicate that efficient digestion of seeds requires multiple digestive processes. The gizzard, responsible for mechanical digestion, plays a key role in seed survival. Omnivorous birds, which have relatively light gizzards compared to pure herbivores or granivores, are thus most likely to disperse seeds successfully. Regardless of digestive strategy, small seeds with tough seed coats are most resistant to digestion and may be adapted to endozoochorous dispersal by waterbirds.

The impact of brick (Agrochola circellaris Hufn.) and owlet moths (Lepidoptera: Noctuidae) on the health of seeds of field elms (Ulmus minor Mill.) in the landscape parks of the Świętokrzyskie Province

Abstract In the period of 2012-2013, a research was conducted to investigate the insects damaging the seeds of field elm (Ulmus minor Mill.). The aim of the research was to specify the damages to field elm seeds caused mainly by the brick (Agrochola circellaris) and to indicate the possible dependence between the number of damaged seeds by the caterpillars of this moth and stand density. The research was conducted in the areas of Cisów-Orłowiny Landscape Park (C-OLP) and Nida Landscape Park (NLP) in the Świętokrzyskie Province. In both parks, there were two test stands situated, each of which covered the material collected from the trees. The number of field elms ranged from four to six. Furthermore, a sample of 300 seeds were randomly collected from each tree. The elms in Cisów-Orłowiny Landscape Park were observed in full density stands (fully stocked stands); however, these trees in Nida Landscape Park were growing in loose density stands (under-stocked stands). In total, there were 12,000 seeds collected from 20 trees. The analysis of the collected research material demonstrated that 436 seeds from the field elms (Ulmus minor) were damaged by the brick (Agrochola circellaris). It constituted 3.6% of the total number of collected samples (Table 1). In the seed samples collected from the test stands in Cisów-Orłowiny Landscape Park, the damages caused by the caterpillars of the brick moth ranged between 0.8% and 2.9%. In the case of seed samples collected from Nida Landscape Park, the damages caused by the caterpillars of the brick moth were greater and ranged between 4.1% and 6.5%. The percentage of undamaged seeds ranged between 94.4% in Cisów-Orłowiny Landscape Park and 84.7% in Nida Landscape Park, which constituted, on an average, 89.5% for both parks. The 6.8% of the seeds were also damaged by other insects. The results of the research showed the dependence between the number of field elm seeds damaged by the brick Agrochola circellaris and the stand density (Table 2). The seeds collected from trees growing in the Nida Landscape Park in loose density stands (under-stocked stands) were twice as frequently damaged than those collected from the trees growing in Cisów-Orłowiny Landscape Park in full density stands. Also, the damages caused by other insects were greater among the seeds collected from trees growing in loose density stands than in full density stands (Table 1).

Same but different: Diversity and complexity of an arthropod trophic network and comparative seed viability of an invasive and a native legume species

Exotic species are species established outside of their natural range and include invasive species, which are the second most important cause of biodiversity loss worldwide and a high risk factor for fragile ecosystems. The exotic species Leucaena leucocephala, a high-risk invasive species, has been introduced to Andean tropical dry forests of Colombia. Here, we compare the complexity and structure of the arthropod trophic networks of the seeds of two legume species, Senegalia riparia (native) and L. leucocephala (exotic), and also evaluate seed germination potential after Bruchinae emergence in comparison with that of undamaged seeds. We found 16 species of arthropods associated with both legume seeds, but the native species had more parasitoids, causing its network to be more dense and complex than that of the exotic species. Four arthropod species connected the two networks. The native species seeds already used for beetle development had the lowest germination percentage, whereas those of the exotic species exhibited the highest. Comparing the structure of seed feeder communities and their effects on germination in exotic and native legumes is essential for understanding how exotic species relate to native communities and how anthropogenic changes affect species diversity, ecosystem dynamics, and community structure and interactions.

MANUFACTURE AND EVALUATION OF A SIMPLE PROTOTYPE OF PEANUT SHELLER

A power-operated peanut sheller was manufactured and the performance was evaluated under different operational conditions. The experiments were conducted at drum rotary speeds of 150, 200, 250 and 300 rpm (2.0, 2.67, 3.33 and 4 m/s.), feeding rates of 170, 210 and 250 kg/h and air speeds of 4.9, 6.8 and 8.8 m/s. The performance was evaluated in terms of output seed damage, shelling losses, undamaged seeds, un-shelling pods, shelling efficiency and machine productivity as well as cleaning ratio. The lowest seeds damaged and shelling losses of 2.45 and 1.32% while the highest undamaged seeds and shelling efficiency of 97.55 and 96.23% were obtained at drum speed of 150 rpm (2.0 m/s) and feeding rate of 170 kg/h. The highest machine productivity of 250 kg/h was obtained at drum speed of 300 rpm (4m/s.) and feeding rate of 250 kg/h. The highestcleaning ratio 98 % was obtained at drum rotary speed of 150 rpm and air speed of 8.8 m/s. But the lowest cleaning ratio of 94.8% was obtained at drum rotary speed of 300 rpm and air speed of 4.9 m/s.

Weeding volatiles reduce leaf and seed damage to field-grown soybeans and increase seed isoflavones

Field experiments were conducted over 3 years (2012, 2013, and 2015), in which half of the young stage soybean plants were exposed to volatiles from cut goldenrods three times over 2–3 weeks, while the other half remained unexposed. There was a significant reduction in the level of the total leaf damage on exposed soybean plants compared with unexposed ones. In 2015, the proportion of damage to plants by Spodoptera litura larvae, a dominant herbivore, was significantly less in the exposed field plots than in the unexposed plots. Under laboratory conditions, cut goldenrod volatiles induced the direct defenses of soybean plants against S. litura larvae and at least three major compounds, α-pinene, β-myrcene, and limonene, of cut goldenrod volatiles were involved in the induction. The number of undamaged seeds from the exposed plants was significantly higher than that from unexposed ones. Concentrations of isoflavones in the seeds were significantly higher in seeds from the exposed plants than in those from the unexposed plants. Future research evaluating the utility of weeding volatiles, as a form of plant–plant communications, in pest management programs is necessary.

Susceptibility of some cowpea varieties to the seed beetle Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae)

The study evaluated seven cowpea Vigna unguiculata L. Walp. varieties: IT89K-568-18, IFE-98-12, IT81P-994, IT89K-288, IT96-660, ?Milk? and ?Drum? for susceptibility to the seed beetle, Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae). Seed samples (100 g) of each variety were infested with 5 pairs of the seed beetle (1-2 days old) with three replications at 30?20C and relative humidity of 69-72%. The parameters evaluated included: number of damaged and undamaged seeds, percentage seed weight loss, mean number of emerged adults, median developmental period and susceptibility index. The percentage seed weight loss in IT96-660 was significantly (p<0.05) higher than in IT89K-568-18, IT89K-288 and ?Milk?. The mean number of seeds damaged in IFE-98-12 was significantly (p<0.05) higher than in IT89K-568-18, IT81P-994, IT89K-288, IT96-660 and ?Milk?. The median developmental period in ?Milk? was significantly (p<0.05) higher than in IT89K-568-18, IFE-98-12, IT96-660 and ?Drum?. IFE-98-12 and IT89K-568-18 with susceptibility index of 10.4 and 7.8 were rated highly susceptible and moderately susceptible, respectively. The number of emerged adults was highly significant and positively correlated with the percentage seed weight loss. Results obtained showed that these cowpea varieties were relatively susceptible to C. maculatus attack in storage suggesting the need for their proper preservation against the insect.