Abundance of Rice Root Aphid Among Selected Plant Species and on Plants Grown With Different Soil-Surface Media

The rice root aphid, Rhopalosiphum rufiabdominalis (Sasaki), is distributed worldwide and colonizes a wide range of plants. However, relatively little is known about the suitability of different host plants, optimal rearing techniques, and the aphid’s impact on plant fitness. To improve understanding of these factors, laboratory experiments were conducted to compare the abundance of rice root aphid on plants grown using three different soil-surface media and among selected monocotyledonous and dicotyledonous plants. Rice root aphid was more abundant on plants grown with a sandy soil surface than a surface with fine wood chips or only bare non-sandy soil. Rice root aphid was more abundant on ‘Elbon’ rye than on ‘Bart 38,’ ‘Dart,’ ‘Fletcher’ and ‘Ramona 50’ wheat. More winged rice root aphids were produced on Elbon rye than on Dart wheat, but the number of winged aphids on Elbon rye did not differ from that on other wheat lines. Rice root aphid was more abundant on Elbon rye and ‘TAM 110’ wheat than on ‘Marmin,’ ‘Marshall’ and ‘Sharp’ wheat. Additional observations with monocotyledonous plants showed that abundance of rice root aphid on ‘Kivu 85’ triticale was comparable to that on Elbon rye. Rice root aphid did not reproduce on potato or soybean, although winged adults persisted up to 24 days on caged potato plants. The implications of differential abundance of rice root aphid on plants are discussed in regard to colony rearing, future experiments and possible pest management considerations

Temperature Effects on Development of Three Cereal Aphid Parasitoids (Hymenoptera: Aphidiidae)

Temperature is an important climatological variable that influences the biology and ecology of insects. Poor climatic adaptation can limit the effectiveness of parasitic insects in biological control. Two exotic parasites (Syrian Diaeretiella rapae (M\u27Intosh) and Argentinean Aphidius colemani Viereck) imported for biological control of the Russian wheat aphid, Diuraphis noxia (Mordvilko), and one native parasite (Diaeretiella rapae) were reared in growth chambers in three fluctuating temperature regimes with average daily temperatures of 12, 18, and 24°C. Estimates of temperature thresholds for immature development were 3.3, 3.5, and 2.8°C, for Oklahoman D. rapae, Syrian D. rapae, and A. colemani, respectively. Estimates of thermal require- ments for development from egg to adult were 297, 278, and 301 degree-days for the three parasitoids. Dry weights of adults reared in different fluctuating temperature regimes did not differ significantly among sexes, but adults from regimes with low average temperatures of 12 and 18°C had significantly greater weights than those reared in a regime with an average temperature of 24°C. Results suggest that developmental response to temperature will not limit the effectiveness of the exotic parasites in biological control

Abundance of Rice Root Aphid Among Selected Plant Species and on Plants Grown With Different Soil-Surface Media

The rice root aphid, Rhopalosiphum rufiabdominalis (Sasaki), is distributed worldwide and colonizes a wide range of plants. However, relatively little is known about the suitability of different host plants, optimal rearing techniques, and the aphid’s impact on plant fitness. To improve understanding of these factors, laboratory experiments were conducted to compare the abundance of rice root aphid on plants grown using three different soil-surface media and among selected monocotyledonous and dicotyledonous plants. Rice root aphid was more abundant on plants grown with a sandy soil surface than a surface with fine wood chips or only bare non-sandy soil. Rice root aphid was more abundant on ‘Elbon’ rye than on ‘Bart 38,’ ‘Dart,’ ‘Fletcher’ and ‘Ramona 50’ wheat. More winged rice root aphids were produced on Elbon rye than on Dart wheat, but the number of winged aphids on Elbon rye did not differ from that on other wheat lines. Rice root aphid was more abundant on Elbon rye and ‘TAM 110’ wheat than on ‘Marmin,’ ‘Marshall’ and ‘Sharp’ wheat. Additional observations with monocotyledonous plants showed that abundance of rice root aphid on ‘Kivu 85’ triticale was comparable to that on Elbon rye. Rice root aphid did not reproduce on potato or soybean, although winged adults persisted up to 24 days on caged potato plants. The implications of differential abundance of rice root aphid on plants are discussed in regard to colony rearing, future experiments and possible pest management considerations

Effects of the Subterranean Aphid [\u3ci\u3eGeoica utricularia\u3c/i\u3e (Passerini)] on Forage Yield and Quality of Sand Lovegrass

In 1977 at Mead, Nebraska, replicated plots in two sand lovegrass (Eragroslis trichodes) nurseries naturally infested with root aphids (Geoica ufricularia Passerini) were treated with soil drenches of carbofuran and disulfoton (2.24 kg/ha AI) toquantify the economic importance of these aphids. In a nursery of ‘Nebraska 27’ sand lovegrass, the carbofurnn and disulfoton treated plots produced 45% and 16% more forage, respectively, than the untreated plots. In a nursery of another Nebraska experimental strain, the treated plots produced more forage than the untreated plots but the differences were not significant. There were no differences among treated and control plots in either nursery for dry matter, protein, and in vitro dry matter digestibility percentages

Effects of the Subterranean Aphid [\u3ci\u3eGeoica utricularia\u3c/i\u3e (Passerini)] on Forage Yield and Quality of Sand Lovegrass

In 1977 at Mead, Nebraska, replicated plots in two sand lovegrass (Eragroslis trichodes) nurseries naturally infested with root aphids (Geoica ufricularia Passerini) were treated with soil drenches of carbofuran and disulfoton (2.24 kg/ha AI) toquantify the economic importance of these aphids. In a nursery of ‘Nebraska 27’ sand lovegrass, the carbofurnn and disulfoton treated plots produced 45% and 16% more forage, respectively, than the untreated plots. In a nursery of another Nebraska experimental strain, the treated plots produced more forage than the untreated plots but the differences were not significant. There were no differences among treated and control plots in either nursery for dry matter, protein, and in vitro dry matter digestibility percentages

Parasitism, Adult Emergence, Sex Ratio, and Size of \u3ci\u3eAphidius Colemani\u3c/i\u3e (Hymenoptera: Aphidiidae) on Several Aphid Species

Aphidius colemani Viereck parasitizes several economically important aphid pests of small grain crops including the greenbug, Schizaphis graminum and the Russian wheat aphid, Diuraphis noxia. The ability of A. colemani to switch from S. graminum to several species of aphids common to agricultural and associated non-agricultural ecosystems in the Great Plains, and the effects of host-change on several biological parameters that influence population growth rate were determined. Female A. colemani parasitized and developed to adulthood in nine of 14 aphid species to which they were exposed in the laboratory. All small grain feeding aphids except Sipha flava were parasi­tized. Two sunflower feeding species (Aphis nerii and A. helianthi) and two crucifer feeding species (Lipaphis erysimi and Brevicoryne brassicae) were parasitized, as was the cotton aphid. Aphis gossypii. The average percentage of aphids parasitized differed significantly among host aphid species. as did the percentage of parasitoids surviving from the mummy to the adult stage and the time required for immature development. The sex ratio of adults that enclosed from the various hosts did not differ significantly among species. Dry weights of adult parasitoids differed significantly among host species. Adults from S. graminum weighed most (0.054 mg) while those emerging from A. helianthi weighed least (0.020 mg). Results are discussed in terms of strategies for classical biological control of aphid pests of cereals

Shone-Anomalie: Fallbericht und Hintergrund

Zusammenfassung: Die Shone-Anomalie wurde 1963 erstmals beschrieben und stellt eine seltene kongenitale kardiovaskuläre Missbildung mit verschiedenen linkskardialen stenotischen Läsionen dar. Die klassische Form besteht aus einem fibrösen supravalvulären Mitralring, einer fallschirmartigen Deformation der Mitralklappe mit nur einem Papillarmuskel ("parachute mitral valve"), einer subvalvulären Aortenstenose und einer Aortenisthmusstenose. Es gibt nur vereinzelte perioperative Fallberichte von erwachsenen Patienten mit dieser kardiovaskulären Missbildung. Allerdings können Patienten mit einer undiagnostizierten, inkompletten Form der Shone-Anomalie auch im Erwachsenenalter für nichtherzchirurgische Operationen vorgesehen sein. In dem vorliegenden Fallbericht wird das anästhesiologische Management einer Patientin, die für eine abdominale Hysterektomie vorgesehen war und an einer bisher nichtdiagnostizierten Shone-Anomalie litt, beschriebe

Optimal Inapproximability Results for MAX-CUT and Other 2-Variable CSPs?

In this paper we show a reduction from the Unique Games problem to the problem of approximating MAX-CUT to within a factor of αGW + ∈, for all ∈ \u3e 0; here αGW ≈ .878567 denotes the approximation ratio achieved by the Goemans-Williamson algorithm [26]. This implies that if the Unique Games Conjecture of Khot [37] holds then the Goemans-Williamson approximation algorithm is optimal. Our result indicates that the geometric nature of the Goemans-Williamson algorithm might be intrinsic to the MAX-CUT problem. Our reduction relies on a theorem we call Majority Is Stablest. This was introduced as a conjecture in the original version of this paper, and was subsequently confirmed in [45]. A stronger version of this conjecture called Plurality Is Stablest is still open, although [45] contains a proof of an asymptotic version of it. Our techniques extend to several other two-variable constraint satisfaction problems. In particular, subject to the Unique Games Conjecture, we show tight or nearly tight hardness results for MAX-2SAT, MAX-q-CUT, and MAX-2LIN(q). For MAX-2SAT we show approximation hardness up to a factor of roughly .943. This nearly matches the .940 approximation algorithm of Lewin, Livnat, and Zwick [41]. Furthermore, we show that our .943... factor is actually tight for a slightly restricted version of MAX-2SAT. For MAX-q-CUT we show a hardness factor which asymptotically (for large q) matches the approximation factor achieved by Frieze and Jerrum [25], namely 1 − 1/q + 2(ln q)/q2 . For MAX-2LIN(q) we show hardness of distinguishing between instances which are (1−∈)-satisfiable and those which are not even, roughly, (q−∈/2)-satisfiable. These parameters almost match those achieved by the recent algorithm of Charikar, Makarychev, and Makarychev [10]. The hardness result holds even for instances in which all equations are of the form xi − xj = c. At a more qualitative level, this result also implies that 1 − ∈ vs. ∈ hardness for MAX-2LIN(q) is equivalent to the Unique Games Conjecture