Feeding behavior and development response of the perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae) on multiple crop seeds combinations

The perilla seed bugs, Nysius plebeius Distant and Nysius hidakai Nakatani, are emerging pests of several field crop species including perilla crop in Korea. Here, we investigated the oviposition, nymphal mortality, development, adult emergence, adult longevity, adult weight and female ratio of N. plebeius and N. hidakai on multiple (MC) and double (DC) combinations of five crop seed species: perilla [Perilla frutescens (L.) Britton.], sesame (Sesamum indicum L.), sorghum [Sorghum bicolor (L.)], proso millet (Panicum miliaceum L.), and foxtail millet (Setaria italic L.) in no-choice test. The life-history variables of N. plebeius and N. hidakai were significantly influenced by the crop seed combinations. The most preferred crop seed combinations for oviposition were MC (perilla + sorghum + sesame + proso millet + foxtail millet), followed by DC (perilla + foxtail millet and perilla + sorghum), whereas the least preferred seed combination was DC (proso millet + foxtail millet). Both Nysius sp. were developed faster in MC (perilla + sorghum + sesame + proso millet + foxtail millet), with minimal nymphal mortality, higher adult emergence, longer adult longevity and heavier adult weight. The positive adult bug’s performance on the MC (perilla + sorghum + sesame + proso millet + foxtail millet) may be due to the nutrient contents and physicochemical components associated with the crop seeds. Further, the findings of this study are discussed in terms of bug's behavioral response to crop seed species combinations and management strategies of Nysius sp. as an alternative to chemical management.     

Artificial radiofrequency driven life-table parameters of perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae)

The genus Nysius (Hemiptera: Lygaeidae) are polyphagous pests of various plants that damage seeds, foliage, and flowers. Here, we studied the life-table parameters and adult performances of Nysius plebeius Distant and Nysius hidakai Nakatani after exposure to five radiofrequencies: 0 (control), 5, 10, 20, and 30 kHz in infested perilla seeds. In addition, we measured the follow on effects of treatment for four generations (Parent, F1-, F2-, and F3-generation), for both Nysius species. Radiofrequency application significantly affected the life-table parameters of both Nysius species. Radiofrequency exposures affected bug oviposition, developmental period, adult weight, and longevity. Exposure also negatively affected the fecundity of subsequent generations; total developmental period from egg to adult emergence was longer while adult longevity was shorter in the radiofrequency treatments than in the untreated control. Low radiofrequency levels had the greatest effect on the life-table parameters of Nysius species, with the lowest rate of adult emergence and the shortest adult longevity at 5 kHz. The potential of using Nysius bug susceptibilities to radiofrequency as an alternative to chemical treatment is discussed.     

The effect of different host plants on the reproduction and longevity of Nysius natalensis

Nysius natalensis Evans (Hemiptera: Orsillidae) is a pest of sunflower in South Africa. Adults invade sunflower fields from their weedy hosts which occur inside crop fields and on surrounding headlands. The host plant suitability for survival and reproduction as well as the effect of within‐generation host switching was studied on different wild host plants and sunflower. Life history parameters used to assess host plant suitability were F₁ adult survival, pre‐oviposition period, fecundity, and longevity. Nymphs and adults were provided with stems and seeds of five host plants, viz., Amaranthus hybridus L. (Amaranthaceae), Portulaca oleracea L. (Portulacaceae), Chenopodium album L. (Chenopodiaceae), Conyza albida Spreng. (Asteraceae), and sunflower, Helianthus annuus L. (Asteraceae). Nymphs were reared on crushed seed of the five plant species. After completion of the nymphal stage, emerging adults of each host plant group were provided with seed of a different host plant species for food. Adults did not survive long on stems only and very few eggs were laid. Seeds of the host plant species were shown to be an essential source of nutrients for N. natalensis reproduction, whereas the vegetative plant parts were unsuitable. Nymphal food and host‐plant switching between the nymphal and adult stages significantly affected the pre‐oviposition period. Nymphal and adult food source also affected female longevity. The number of eggs laid was not influenced by nymphal food, but was influenced by adult food and the switch between nymphal and adult food. The comparative attractiveness of sunflower and wild host plants for oviposition was also investigated and showed that females preferred to lay eggs on wild host plants, compared with sunflower. These results may explain why N. natalensis will lay their eggs on sunflower after weeds in the vicinity are controlled, or senesce toward the end of the growing season.     

Revision of the lygaeid genus Nysius (Heteroptera: Lygaeidae: Orsillinae) of Japan,with description of a new species

Japanese species of the lygaeid–orsilline genus Nysius were revised, and five species including a new species, N. hidakai, were recognized. Male and female genitalia of all the species were illustrated, and a key to species of Japanese Nysius was provided. The DNA barcoding information of each species except N. expressus were recorded.     

Preferential removal of non-injured seeds by an omnivorous ant,Tetramorium tsushimae Emery,in the seed dispersal of Chamaesyce maculata (L.) small

To elucidate roles of an omnivorous ant, Tetramorium tsushimae Emery, against pre-dispersal seed consumers in the seed dispersal of Chamaesyce maculata (L.) Small, the effects of the seed injury by a stinkbug, Nysius plebeius Distat, on the seed removal by the ant and the germination rate were examined in laboratory experiments. The ants of T. tsushimae removed more frequently non-injured seeds than injured seeds. Therefore, low removal frequency of injured seeds by T. tsushimae ants might facilitate the increase in removal frequency of non-injured seeds, consequently leading to efficient seed dispersal of C. maculata. The germination rate of injured seeds that N. plebeius nymphs sucked was conspicuously lower than the non-injured seeds. The germination rate of seeds that T. tsushimae ants carried out of their nest was similar to that of the non-injured seeds. Thus, seed removal by T. tsushimae ants has hardly effects on the germination of these seeds. Therefore, the preferential removal of non-injured seeds by T. tsushimae ants might contribute to the dispersal success of C. maculata seeds. These results might show a novel interaction between myrmecochorous plants and ants in which the assessment of seed quality by ants contributes to the reproductive success of plants.     

Seed predator deterrence by seed-carrying ants in a dyszoochorous plant, <Emphasis Type="Italic">Chamaesyce maculata</Emphasis> L. Small (Euphorbiaceae)

Seeds are often carried by omnivorous ants even if they do not carry elaiosomes. Although many seeds carried by ants are consumed, both seeds abandoned during the seed carrying and leftover seeds are consequently dispersed (dyszoochory). These non-myrmecochorous seeds do not necessarily attract ants quickly. Therefore, these seeds often seem to be exposed to the danger of consumption by pre-dispersal seed predators. We propose the hypotheses, “seed predator deterrence hypothesis” that plants may benefit from seed-carrying ants if they deter seed predators from visiting plants, and seed-carrying ants may play additional roles in plant reproductive success, besides dyszoochory by ants. To test the hypotheses, we investigated the abundance of seed-carrying ants of the species Tetramorium tsushimae Linnaeus and Pheidole noda Smith F., and of the seed predatory stinkbug, Nysius plebeius Distat, on the spotted sandmat, Chamaesyce maculata L. Small, of which the seeds have no elaiosomes but are consumed by both ants and bugs. In the field, ants and stinkbugs seldom encountered each other on the plant. The number of stinkbugs beneath the plants with ants was smaller than that beneath the plants without ants. In laboratory experiments, the number of stinkbugs on the shoot was smaller when ants were present than when they were absent. These results might support the seed predator deterrence hypothesis: the probability of seed predation by stinkbugs seems to be reduced by the ant visits on plants and/or the existence of ants beneath the plants. This study highlights a new ant–plant interaction in seed dispersal by ants.     

Millet preference, effects of planting date on infestation, and adult and larval use of proso millet by Ostrinia nubilalis (Lepidoptera: Crambidae)

The interaction between millet and European corn borer, Ostrinia nubilalis (Hübner), was investigated to gain insight into whether millet could serve as a refuge or trap crop for O. nubilalis management. In 1995, 1996, and 1999, millet selection studies were conducted in North Dakota and New York with four millet species. Proso millet, Panicum milliaceum L., had the highest infestation and widest distribution of O. nubilalis developmental stages, indicating the presence of both univoltine and bivoltine ecotypes. Siberian foxtail millet, Setaria italica (L.) Beauvois, harbored the greatest number of adults, followed by German foxtail millet, Setaria italica (L.) Beauvois. These two millets appeared to serve as better aggregation sites than proso millet. In North Dakota in 1997, proso millet planting date studies showed later planting dates were more heavily infested than earlier dates; in 1998, this trend was reversed. The change in trends between years was probably a result of differences in the respective growing seasons and subsequent differences in O. nubilalis flights. Adult sampling showed that both old and young females aggregated in proso millet during the day; however, at night, it appeared that young females moved out of millet to oviposit, whereas old females remained in millet. Egg masses were detected in proso millet over a 7-d period in 1997 and a 4-d period in 1998. Larval sampling showed planting proso millet between late May and mid-June may maximize the presence of individuals from both O. nubilalis ecotypes. Once the optimal combination of planting date, plant density, and millet type is found, millet may serve as an effective refuge or trap crop for O. nubilalis management.     

A straight-forward seed production technology system for foxtail millet (Setaria italica)

For autogamous crops, a precondition for using heterosis is to produce sufficient pure male-sterile female parents that can be used to produce hybrid seeds. To date, cytoplasmic male sterility(CMS)and environment-sensitive genic male sterility(EGMS) have been used commercially to exploit heterosis for autogamous species. However, neither CMS nor EGMS has been established for foxtail millet(Setaria italica). Here, we report on the establishment and application of a seed production technology(SPT)...     

Herbicidal activity of the antibiotics geldanamycin and nigericin

Geldanamycin and nigericin, phytotoxic metabolites from a strain ofStreptomyces hygroscopicus, were tested for herbicidal activity and selectivity on a range of crop and weed species. In petri dish bioassays, geldanamycin reduced radicle growth of all species tested, whereas nigericin inhibited 7 of 10. The two compounds in mixture appeared to be additive rather than synergistic in effect. In assays with seeds and seedlings in field soil, geldanamycin showed significant preemergence activity on proso millet, barnyardgrass, garden cress, and giant foxtail. It had no postemergence herbicidal effect on any of the species tested. Nigericin had preemergence activity on garden cress and large crabgrass and postemergence activity on garden cress and velvetleaf. The postemergence effect of nigericin on velvetleaf was especially striking, with leaves showing symptoms of injury within 24–48 h of treatment. Doses as low as 0.3 kg/ha caused damage. The primary herbicidal effect of both compounds was slowing of seed germination or seedling growth, although some plants were killed, especially at higher rates of application. Herbicidal effects were most pronounced for 1 to 2 weeks after treatment and diminished thereafter.Michigan Agricultural Experiment Station journal article no. 13012.     

Development and characterization of twenty-five new polymorphic microsatellite markers in proso millet (Panicum miliaceum L.)

Millets such as proso millet have excellent nutritional properties and could become a basic resource for crop breeding programs and food diversification. In this study, 25 polymorphic microsatellite markers were developed and characterized through construction of an SSR-enriched library from genomic DNA of proso millet (Panicum miliaceum L.). In total, 110 alleles were detected, with an average of 4.4 alleles per locus. Values of major allele frequency (M _AF ) and expected heterozygosity (H _E ) ranged from 0.36 to 0.98 (mean = 0.73) and from 0.04 to 0.74 (mean = 0.37), respectively. The mean genetic similarity coefficient was 0.3711, indicating that among 50 accessions of proso millet there was wide genetic variation. The newly developed microsatellite markers should be useful tools for assessing genetic diversity, understanding population structure, and breeding of proso millet.     

Experiments on the effects of charring on <Emphasis Type="Italic">Setaria italica</Emphasis> (foxtail millet)

This study aims to better understand taphonomical effects relevant to Setaria italica (foxtail millet), particularly the deformation caused by charring in fully-formed grains, and the potential preservation of underdeveloped seeds. Foxtail millet is a staple grain commonly found in Neolithic and later sites across Eurasia after initial domestication in northern China. Precise control of atmospheric conditions enabled determination of ideal parameters for charring without seed destruction. These experiments were able to produce charred seeds that strongly resemble archaeological specimens, making three key findings: (1) lateral expansion found in many ancient foxtail millet seeds indicates that charring occurred with the seeds in the husks. (2) Oxidizing conditions produced far better results in terms of seed preservation and retention of identifiable characteristics. (3) Smaller and less developed or ‘filled’ seeds survived in the same conditions as larger, plump seeds. These results allow for better interpretation of depositional context of millet seeds, and point to heat treatment during the de-husking process as a common way for seeds to enter the archaeological record.     

Herbicidal activity of the antibiotics geldanamycin and nigericin

Geldanamycin and nigericin, phytotoxic metabolites from a strain ofStreptomyces hygroscopicus, were tested for herbicidal activity and selectivity on a range of crop and weed species. In petri dish bioassays, geldanamycin reduced radicle growth of all species tested, whereas nigericin inhibited 7 of 10. The two compounds in mixture appeared to be additive rather than synergistic in effect. In assays with seeds and seedlings in field soil, geldanamycin showed significant preemergence activity on proso millet, barnyardgrass, garden cress, and giant foxtail. It had no postemergence herbicidal effect on any of the species tested. Nigericin had preemergence activity on garden cress and large crabgrass and postemergence activity on garden cress and velvetleaf. The postemergence effect of nigericin on velvetleaf was especially striking, with leaves showing symptoms of injury within 24–48 h of treatment. Doses as low as 0.3 kg/ha caused damage. The primary herbicidal effect of both compounds was slowing of seed germination or seedling growth, although some plants were killed, especially at higher rates of application. Herbicidal effects were most pronounced for 1 to 2 weeks after treatment and diminished thereafter.     

Importance of spittle bugs, Locris rubens (Erichson) and Poophilus costalis (Walker) on sorghum in West and Central Africa, with emphasis on Nigeria

Locris rubens (Erichson) (Cercopidae: Homoptera) and Poophilus costalis (Walker) (Aphrophoridae: Homoptera) are endemic pests of sorghum (Sorghum bicolor (L.) Moench) in Nigeria and some other countries in West and Central Africa. Other hosts are maize, pearl millet, rice, sugarcane, and grasses. On sorghum, L. rubens lays eggs in the epidermis of the leaf sheath. There are five nymphal instars and development from egg to adult takes about 33 days. Both species of spittle bugs feed on all growth stages and all parts of sorghum, including the panicle. Feeding symptoms include yellow leaf blotching. Severe infestations often kill young leaves and plants. Under artificial infestation in cages, the severity of damage and associated symptoms as well as grain yield loss increased with an increase in the population density of spittle bugs. Infestation by 15 pairs of adult L. rubens     

Heteromorphic seeds of wheat wild relatives show germination niche differentiation

• Crop wild relatives are fundamental genetic resources for crop improvement. Wheat wild relatives often produce heteromorphic seeds that differ in morphological and physiological traits. Several Aegilops and Triticum species possess, within the same spikelet, a dimorphic seed pair, with one seed being larger than the other. A comprehensive analysis is needed to understand which traits are involved in seed dimorphism and if these aspects of variation in dimorphic pairs are functionally related.
• To this end, dispersal units of Triticum urartu and five Aegilops species were X‐rayed and the different seed morphs weighed. Germination tests were carried out on seeds, both dehulled and left in their dispersal units. Controlled ageing tests were performed to detect differences in seed longevity among seed morphs, and the antioxidant profile was assessed in terms of antioxidant compounds equipment and expression of selected antioxidant genes. We used PCA to group seed morphs sharing similar patterns of germination traits, longevity estimates and antioxidant profile.
• Different seed morphs differed significantly in terms of mass, final germination, germination timing, longevity estimates and antioxidant profile in most of the tested species. Small seeds germinated slower, had lower germination when left in their dispersal units, a higher antioxidant potential and were longer‐lived than large seeds. The antioxidant gene expression varied between morphs, with different patterns across species but not clearly reflecting the phenotypic observations.
• The results highlight different trait trade‐offs in dimorphic seeds of Aegilops and T. urartu, affecting their germination phenology and longevity, thereby resulting in recruitment niche differentiation.

     

Longevity of pearl millet (Pennisetum glaucum) seeds harvested at different stages of maturity

The storage potential of seeds harvested at weekly intervals after controlled pollination was studied in three diverse cytoplasmic male sterile pearl millet (Pennisetum glaucum) lines. In the first experiment in 1989, a comparison of p₅₀ (time for viability to decline to 50% during storage) among seeds of the line DSA 105A harvested 14, 21, 28, 35 and 42 days after pollination (DAP), and then stored at 35°C with 15% moisture content or 40°C with 13% moisture content, showed that those harvested 35 DAP had the greatest longevity. In the second experiment in 1990, a comparison of p₅₀ within the lines 5141A and L 67A harvested 28, 35 and 42 DAP, and then stored at 40°C with 13% moisture content, showed that seeds of both lines harvested 42 DAP had the greatest longevity. In both the seasons, and in all three lines, maximum seed longevity (p₅₀) was attained one week after physiological maturity (defined as the end of the grain filling period), which is therefore the optimum time of harvest to obtain good quality seeds for conservation.     

Forty‐nine new host plant species for Bemisia tabaci (Hemiptera: Aleyrodidae)

The sweetpotato whitefly, Bemisia tabaci (Gennadius), is a worldwide pest of numerous agricultural and ornamental crops. In addition to directly feeding on plants, it also acts as a vector of plant viruses of cultivated and uncultivated host plant species. Moreover, host plants can affect the population dynamics of whiteflies. An open‐choice screening experiment was conducted with B‐biotype B. tabaci on a diverse collection of crops, weeds, and other indigenous plant species. Five of the plant species were further evaluated in choice or no‐choice tests in the laboratory. The results reveal 49 new reproductive host plant species for B. tabaci. This includes 11 new genera of host plants (Arenaria, Avena, Carduus, Dichondra, Glechoma, Gnaphalium, Molugo, Panicum, Parthenocissus, Trianthema, and Triticum) for this whitefly. All species that served as hosts were acceptable for feeding, oviposition, and development to the adult stage by B. tabaci. The new hosts include three cultivated crops [oats (Avena sativa L.), proso millet (Panicum miliaceum L.), and winter wheat (Triticum aestivum L.)], weeds and other wild species, including 32 Ipomoea species, which are relatives of sweetpotato [I. batatas (L.) Lam.)]. Yellow nutsedge, Cyperus esculentus L., did not serve as a host for B. tabaci in either open‐choice or no‐choice tests. The results presented herein have implications for whitefly ecology and the numerous viruses that B. tabaci spreads to and among cultivated plants.     

Mung bean (<Emphasis Type="Italic">Vigna radiata</Emphasis>) cultivars mediated oviposition preference and development of <Emphasis Type="Italic">Callosobruchus chinensis</Emphasis> (Coleoptera: Chrysomelidae: Bruchinae)

The Azuki bean weevil, Callosobruchus chinensis (L.), is a destructive pest of stored mung bean [Vigna radiata (L.) Wilczek] as well as other leguminous seeds. The development of resistant seeds to manage this pest is of current great interest to plant breeders. In this study, we investigated the oviposition preference and development of C. chinensis on two susceptible mung bean cultivars (Seonhwa and Gyeongseon) and one previously reported resistant cultivar (Jangan), compared to the susceptible cowpea (Vigna unguiculata L.), cultivar (Yeonbun) using both multiple-choice and no-choice tests. In addition, the development of C. chinensis was also examined at four constant temperatures (20, 25, 30, and 35 °C). Both tests found cowpea to be the most suitable seed for oviposition. Total developmental time from oviposition to adult emergence ranged from 27.01 to 38.2 days, being shortest on cowpea and longest on the mung bean, cv. Jangan. However, no successful development of C. chinensis larvae on mung bean, cv. Jangan, occurred at any temperature. The highest rate of adult emergence and the longest adult longevity both occurred on cowpea and certain mung bean cultivars (Seonhwa and Gyeongseon), with the dramatic exception of cv. Jangan. These results suggest that the higher preference and performance of C. chinensis on cowpea (3.3 egg/seed) and least on mung bean, cv. Jangan (0.4 egg/seed). This information may facilitate the exploration of resistant genetic materials and chemicals associated with seeds for successful breeding. Further studies should examine the chemicals associated with mung bean cultivars and its resistant mechanism to develop a control method against bruchines.     

Protection of cowpea,Vigna unguiculata L. (Walp.) with Newbouldia laevis (Seem.) extracts against infestation by Callosobruchus maculatus (Fabricius)

Evaluation of protectant ability of Newbouldia laevis (Seem.) extracts against infestation by Callosobruchus maculatus in cowpea, Vigna unguiculata L. (Walp.) was carried out in the laboratory at ambient temperature of 28?±?2?°C and 70?±?5% relative humidity. Extracts from wood ash, leaf, stem and root bark were tested at different concentrations of 0, 1, 2, 3, 4 and 5%. One hundred per cent mortality of adult beetles was achieved at all concentrations within 72?h of treatment with extracts except in wood ash at 1% concentration, but they were significantly different (p?<?0.05) from the controls. All the extracts were still able to cause high beetle mortality after one, two and three months of cowpea storage at high concentrations (4 and 5%) except wood ash, although there was a slight decrease in mortality during the period of storage. All the extracts significantly (p?<?0.05) reduced oviposition and adult emergence of C. maculatus when compared with the controls although the reduction was higher at 5% concentration than others. Adult beetle emergence was completely prevented at higher concentrations (4 and 5%) except in wood ash. Both oviposition and adult emergence increased during the months of storage probably because of the slight reduction in the effectiveness of the extracts. The root bark extract was much more effective in reducing oviposition and adult emergence than others throughout the period of storage. The plant extracts of N. laevis was able to protect the cowpea seeds from damage and prevent weight loss. Cowpea seed damage and weight loss was significantly more (p?<?0.05) in the controls than other for the three-month duration probably because of the more adult emergence. The extracts from N. laevis did not adversely affect the germination of the protected seeds and seed germination ranged from 86.7 to 100%. It has been shown in this study that the extracts of N. laevis were effective against C. maculatus in cowpea although the root bark extract seemed to be the most effective while the wood ash extract was least effective. Their effectiveness, however, slightly decreased during the period of storage. N. laevis could be incorporated into pest management of stored cowpeas since the products are ecologically safe.