Some aspects of feeding responses in the stem borer Chilo partellus swinhoe (Lepidoptera: Pyralidae).

Feeding responses of Chilo partellus larvae to different food sources, were studied. Maize and sorghum were more preferred to artificial diet by the larvae irrespective of their rearing media. Larvae fed on maize and sorghum leaves as well as maize and sorghum stems. The rearing medium did not have any effect on the feeding preference; it could only improve but not induce the feeding behaviour.     

不同寄主上桃蛀螟越冬幼虫体内生化物质变化与抗寒性研究

为预测不同寄主植物上桃蛀螟Conogethes punctiferalis(Guenée)越冬种群的变化,研究了幼虫期取食玉米、高粱和向日葵的桃蛀螟越冬幼虫体内水分和脂肪及血淋巴小分子糖(醇)与抗寒性的关系。与取食高粱和向日葵相比,取食玉米的桃蛀螟幼虫生长发育更好,越冬幼虫体重、脂肪含量显著高于前二者,降低体内含水量时期显著早,12月上旬为74.0%,而前者为82.3%和84.6%,过冷却点显著低。初冬和初春,3种寄主植物上桃蛀螟越冬幼虫的过冷缺点没有显著差异。然而隆冬季节,玉米上越冬幼虫的过冷缺点最低(-17.74℃),其次是高粱(-14.62℃),向日葵的最高(-11.68℃)。这说明,寄主植物对幼虫的生长发育、越冬物质储备及含水量有显著的影响,从而影响了滞育幼虫的抗寒能力。越冬幼虫血淋巴中小分子糖(醇)主要有海藻糖、甘油、肌醇、葡萄糖、山梨醇、半乳糖和甘露糖等。从初冬到隆冬,幼虫体内甘油含量显著上升,提高了15～101.8倍,而葡萄糖的含量变化则相反,越冬幼虫体内甘油含量变化与其抗寒能力的变化一致,说明甘油是越冬幼虫提高抗寒能力的重要物质,而合成甘油需要葡萄糖。     

Assessment of Napier millet (Pennisetum purpureumx P. glaucum) and sorghum (Sorghum bicolor) trap crops for the management of Chilo partellus on maize

Two Napier millet (Pennisetum purpureumxP. glaucum) hybrids, namely PBN 83 and PBN 233 and one sorghum (Sorghum bicolor) variety, SL 44, were assessed for their potential role as a trap crop in the management of the stem borer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) on maize. Oviposition preference and larval survival and development were determined for different test plants under laboratory and screen house conditions. Further, field dispersal of C. partellus larvae was assessed between Napier millet and maize crops. Results from no-choice and dual-choice tests indicated that Napier millet hybrids were preferred for oviposition over maize by C. partellus moths. Sorghum was, however, not preferred over maize in this respect. Napier millet hybrids were poor larval hosts, and a rapid decline in larval numbers was noticed within the first five days after hatching and virtually no larvae survived to pupation. Leaf area eaten by the borer larvae was significantly less on these hybrids than on maize or sorghum. Plant damage was more severe in maize and sorghum than Napier millet hybrids. No appreciable larval shift was noticed from Napier millet hybrids to the adjoining maize crop. The evaluated Napier millet hybrids, therefore, had potential for use as trap crop in C. partellus management. Sorghum, however, did not hold promise in this respect.     

Infochemicals mediating the foraging behaviour of Aleochara bilineata Gyllenhal adults: sources of attractants

Aleochara bilineata Gyll. (Coleoptera: Staphylinidae) adults feed on eggs and larvae of cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae), and might be used to control this pest. We undertook tests in a Y-tube olfactometer to determine if infochemicals are involved in the food foraging behaviour of A. bilineata adults and to precisely determine the potential sources of stimuli. A. bilineata adults oriented toward the stimuli from both the food-plant of the prey (rutabaga: Brassica napus var. napobrassica (L.) Reichb.) and the prey-plant complex (rutabaga infested by cabbage maggot larvae), but adults significantly preferred the effluvia of infested to uninfested rutabaga in a choice test. The sources of infochemicals in the infested rutabaga were the cabbage maggot larvae themselves and their frass. However, in a choice test adults preferred the effluvia of the larvae to that of the damaged rutabaga from which those larvae were obtained. It is not expected that a generalist predator uses precise herbivore-derived signals in food foraging activity, but the preference of A. bilineata adults for the larval volatiles over frass volatiles may reflect the dependence of this species on dipteran pupae for reproduction.     

Host plant selection behaviour of Chilo partellus and its implication for effectiveness of a trap crop

Female lepidopterans can display a hierarchy of preference among potential host species, a trait thought to arise from the balance between attractants and deterrents to which the insects respond. Host plant ranking by moths and larvae of Chilo partellus Swinhoe (Lepidoptera: Crambidae), an important pest of cereals in Africa, was investigated, and whether eggs deposited on specific host plants yield larvae of particular host preferences. Trap plants are used in management of this pest. However, any ‘disagreement’ in host ranking between moths and larvae could potentially reduce effectiveness of trap crops as larvae emigrate to the main crop from the parent’s preferred trap plant. We also investigated whether host plant preference is influenced by the diet upon which larvae fed as part of an integrated assessment of the relationship between host plant selection and learning in C. partellus. Five host plants (all Poaceae) were used: maize (Zea mays L.), sorghum (Sorghum bicolor Moench), Napier grass (Pennisetum purpureum Schumach), and two varieties of signal grass [Brachiaria brizantha (A. Rich.) Stapf], viz., local (henceforth signal grass) and improved (‘Mulato’). In multiple choice tests, C. partellus female moths preferentially oviposited on Napier grass, followed by sorghum, maize, and signal grass, and least preferred ‘Mulato’. Larvae however equally orientated and settled on leaf cuts of maize, sorghum, signal grass, and Napier grass, but least preferred ‘Mulato’. Moreover, eggs from specific host plants did not yield larvae of particular host preferences. Furthermore, oviposition preference was not altered by the larval food. These results imply only a slight ‘disagreement’ in host ranking behaviour between moths and larvae, which is beneficial for trap cropping as larvae would not ‘reject’ the trap plant and appreciably disperse to the neighboring plants. Moreover, absence of larval learning behaviour indicates that regardless of the larval food C. partellus moths would still be attracted to the selected trap plant.     

Egg laying preference of Sesamia nonagrioides (Lepidoptera: Noctuidae) among primary and secondary hosts

Sesamia nonagrioides Lefébvre (Lepidoptera: Noctuidae) has a fairly wide range of host plants. The present study tests the egg-laying preference of S. nonagrioides on four potential host plants (maize, sweet and fiber sorghum and johnsongrass) with respect to several life history traits. No-choice and two-choice tests in all possible combinations were conducted. Concerning no-choice tests, significantly higher number of eggs were laid on sweet sorghum (282.5 eggs/female) in relation to the other tested plants. Moreover, viability of eggs that were laid on sweet sorghum was significantly higher in relation to those that were laid on johnsongrass. Longevity of females reared on maize plants was significantly greater compared with the other test plants except johnsongrass. Furthermore, pre-oviposition period of females reared on maize was significantly longer (2.4-fold) compared with that on sweet sorghum and johnsongrass. Similarly post-oviposition period of females reared on maize was significantly longer compared with that on fiber sorghum. On two choice tests significantly fewer eggs were laid on sweet sorghum than on maize. On the other hand, significantly more eggs were laid on sweet sorghum than on fiber sorghum and johnsongrass. We discuss the potential of secondary hosts to be used as trap plants.     

Prairie grasses as hosts of the northern corn rootworm (Coleoptera: Chrysomelidae)

We evaluated 27 prairie grass species thought to be among those dominant 200 yr ago in the northern midwest as larval hosts of the northern corn rootworm, Diabrotica barberi Smith and Lawrence. Maize (Zea mays L.), spring wheat (Triticum aestivum L.), and grain sorghum (Sorghum bicolor L.) were included as controls for a total of 30 species. Twenty pots of each species were planted in a randomized complete block design. Each pot was infested 5 wk later with 20 neonate northern corn rootworm larvae. Two pots within each species and block were assigned an extraction date of 7 or 14 d after infestation. The remaining two pots from each block were used to monitor adult emergence. The percentage of larvae recovered, change in larval head capsule width, and change in average dry weights varied significantly among the grass species. The highest percentage of larvae was recovered from slender wheatgrass, Elymus trachycaulus (Link), and this was significantly greater than the percentage recovered from all other species including maize for the 14-d sample date. Several additional species were also relatively good hosts, in that the percentage of larvae recovered from these species was not significantly different from maize. The average dry weight of larvae recovered was significantly greater for larvae recovered from maize than for larvae recovered from all other species except slender wheatgrass, when the two samples dates were combined. Overall, adults were produced from only 6 of the 28 species evaluated, and no analysis was performed because of the low numbers. The results of this study are discussed in relation to the potential of alternate hosts of northern corn rootworm to serve as a bridge to survival on transgenic maize.     

Distribution and relative importance of cereal stem borers and their natural enemies in the semi-arid and cool-wet ecozones of the Amhara State of Ethiopia

The distribution and relative importance of lepidopteran and coleopteran stem borers and their natural enemies on maize and sorghum were studied in cereal growing zones of the Amhara State of Ethiopia from 2003 to 2004. Sorghum is the major crop in semi-arid eastern and maize in the cool-wet western zones of the Amhara state. Four administrative zones, 10 districts and 88 localities in the semi-arid ecozone (SAE) and four zones, 19 districts and 71 localities in the cool-wet ecozone (CWE) were chosen for the study. In SAE, the species composition was 91% Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), 8% Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and 1% Sesamia calamistis Hampson (Lepidoptera: Noctuidae). In the CWE, maize and sorghum are grown in different ecozones and thus B. fusca was the dominant species on sorghum, whereas 61% B. fusca and 39% S. calamistis were recorded on maize. Borer density generally increased with crop growth stage. C. partellus parasitism by C. flavipes Cameron (Hymenoptera: Braconidae), which occurred only in SAE, varied among districts ranging from 5% to 39%. In the CWE, unidentified nematodes parasitized medium-sized B. fusca larvae during the wet months. Population of native parasitoids was very low. The coleopteran borer, Rhynchaenus niger (Horn) (Coleoptera: Rhynchophoridae), attacked sorghum plants in both regions. Sorghum yields were negatively related to plant damage variables and positively to larval parasitism and plant growth variables. On maize, plant damage was too low to affect yields. Taylor’s power law indicated aggregated distribution for C. partellus and B. fusca larvae and pupae combined.     

Orientational and directional selectivities of visual neurons in the superior colliculus of the cat

Based on quantitative analyses of the response characteristics of visual neurons in the superior colliculus to moving optical bar stimuli, it is demonstrated for the first time that the visual neurons in superior colliculus of the cat have, to some extent, orientational selectivity. The significance of this selectivity is discussed in reference to its morphological substrate and physiological functions. In addition, both the directional and orientational selectivities in the superior colliculus are relatively weak when compared with those in the primary visual cortex, and the majority of the neurons prefer upward or downward motion in the visual field.     

Effect of fermentation on crude protein and fat contents of crushed grains of maize and sorghum

Cereal grains are conventional energy sources in livestock and poultry rations, while the requisite protein is often supplied by richer sources. Possibilities for the production of crude protein by growing micro-organism on crushed cereal grains was investigated with the aim of obtaining protein-enriched grains for providing both energy and protein in farm animal diets.
Samples of white maize and sorghum were crushed, wetted with distilled water and fermented by Fibrobacter succinogenes, Lactobacillus brevis and a mixed culture of both micro-organisms. Crude protein and either extract values increased with increasing fermentation period. Peak values of both fat and protein were obtained in the fourth week for all fermentations. Highest values of protein were 30·1 and 24·2% respectively for heat-treated sorghum and maize which were both fermented by F. succinogenes. Highest values of fat were 13·1 and 10·6% for maize and sorghum respectively and were obtained from fermentation of heat-treated grains using Lact. brevis. Heat treatment of grains encouraged microbial protein production.     

Homologues of the maize rust resistance gene Rp1-D are genetically associated with a major rust resistance QTL in sorghum

As part of a comparative mapping study between sugarcane and sorghum, a sugarcane cDNA clone with homology to the maize Rp1-D rust resistance gene was mapped in sorghum. The cDNA probe hybridised to multiple loci, including one on sorghum linkage group (LG) E in a region where a major rust resistance QTL had been previously mapped. Partial sorghum Rp1-D homologues were isolated from genomic DNA of rust-resistant and -susceptible progeny selected from a sorghum mapping population. Sequencing of the Rp1-D homologues revealed five discrete sequence classes: three from resistant progeny and two from susceptible progeny. PCR primers specific to each sequence class were used to amplify products from the progeny and confirmed that the five sequence classes mapped to the same locus on LG E. Cluster analysis of these sorghum sequences and available sugarcane, maize and sorghum Rp1-D homologue sequences showed that the maize Rp1-D sequence and the partial sugarcane Rp1-D homologue were clustered with one of the sorghum resistant progeny sequence classes, while previously published sorghum Rp1-D homologue sequences clustered with the susceptible progeny sequence classes. Full-length sequence information was obtained for one member of a resistant progeny sequence class ( Rp1-SO) and compared with the maize Rp1-D sequence and a previously identified sorghum Rp1 homologue ( Rph1-2). There was considerable similarity between the two sorghum sequences and less similarity between the sorghum and maize sequences. These results suggest a conservation of function and gene sequence homology at the Rp1 loci of maize and sorghum and provide a basis for convenient PCR-based screening tools for putative rust resistance alleles in sorghum.     

Structure and evolution of the genomes ofsorghum bicolor andZea mays

Cloned maize genes and random maize genomic fragments were used to construct a genetic map of sorghum and to compare the structure of the maize and sorghum genomes. Most (266/280) of the maize DNA fragments hybridized to sorghum DNA and 145 of them detected polymorphisms. The segregation of 111 markers was analyzed in 55 F₂ progeny. A genetic map was generated with 96 loci arranged in 15 linkage groups spanning 709 map units. Comparative genetic mapping of sorghum and maize is complicated by the fact that many loci are duplicated, often making the identification of orthologous sequences ambiguous. Relative map positions of probes which detect only a single locus in both species indicated that multiple rearrangements have occurred since their divergence, but that many chromosomal segments have conserved synteny. Some sorghum linkage groups were found to be composed of sequences that detect loci on two different maize chromosomes. The two maize chromosomes to which these loci mapped were generally those which commonly share duplicated sequences. Evolutionary models and implications are discussed.     

不同空间尺度下的ALMANAC模型验证

ALMANAC模型最早作为EPIC模型的一部分,用于模拟土壤侵蚀导致的土地生产力的下降．它将试验数据的统计过程和作物生长的机理过程结合起来,是一种典型的基于过程模拟的应用型作物生长模型．如能在不同的空间尺度上验证模型的适用性,无疑会大大扩展模型的应用范围．从这一目的出发,利用美国得克萨斯州19个试验田和9个县的玉米和高粱产量资料及其相关的作物、土壤、田问管理等数据,模拟了1998年田间尺度,1989～1998年县级尺度的平均作物产量．模拟结果表明,ALMANAC模型能够很好地模拟两种不同空间尺度的作物产量,其相对误差在田问尺度上分别为8．9％(高粱)和9．4％(玉米),在县级尺度上分别达到2．6％(玉米)和—0．6％(高粱)．该模型在进行产量预测、掌握作物生长动态,指导农业生产管理和土地利用等方面具有很好的应用前景．     

Chemoattraction of infective larvae of Ancylostoma braziliense to rodent plasmas and to salts

Infective larvae of Anyclostoma braziliense were tested for orientational response to rat plasma, to mouse plasma, to rat plasma fractions, and to salts. A high percentage of larvae accumulated at sources of rat plasma, mouse plasma, rat plasma diffusate, concentrated rat plasma dialysate, and some salts, notably sodium chloride. Because sodium chloride is present at an effective concentration in mammalian plasma, and because this salt may form a gradient between the blood and the skin surface, sodium chloride from the blood may direct the penetrating larvae through host's skin. Preliminary tracking of the larvae in gradients of rat plasma and of sodium chloride suggests that orientation to sources of these attractants was via a taxis, possibly a klinotaxis, whereas accumulation at these sources was via a klinokinesis.     

Comparative Genome Mapping of Sorghum and Maize

Linkage relationships were determined among 85 maize low copy number nuclear DNA probes and seven isozyme loci in an F2 population derived from a cross of Sorghum bicolor ssp. bicolor x S. bicolor ssp. arundinaceum. Thirteen linkage groups were defined, three more than the 10 chromosomes of sorghum. Use of maize DNA probes to produce the sorghum linkage map allowed us to make several inferences concerning processes involved in the evolutionary divergence of the maize and sorghum genomes. The results show that many linkage groups are conserved between these two genomes and that the amount of recombination in these conserved linkage groups is roughly equivalent in maize and sorghum. Estimates of the proportions of duplicated loci suggest that a larger proportion of the loci are duplicated in the maize genome than in the sorghum genome. This result concurs with a prior estimate that the nuclear DNA content of maize is three to four times greater than that of sorghum. The pattern of conserved linkages between maize and sorghum is such that most sorghum linkage groups are composed of loci that map to two maize chromosomes. This pattern is consistent with the hypothesized ancient polyploid origin of maize and sorghum. There are nine cases in which locus order within shared linkage groups is inverted in sorghum relative to maize. These may have arisen from either inversions or intrachromosomal translocations. We found no evidence for large interchromosomal translocations. Overall, the data suggest that the primary processes involved in divergence of the maize and sorghum genomes were duplications (either by polyploidy or segmental duplication) and inversions or intrachromosomal translocations.     

Differences in oviposition behaviour of two sympatric sibling species of the genus Ostrinia

Changes in host preferences are thought to be a major source of genetic divergence between phytophagous insect taxa. In western Europe, two sympatric taxa, O. nubilalis (the European corn borer) and O. scapulalis, feed mainly on maize and hop or mugwort, respectively. These two species may have diverged without geographic isolation after a host shift of ancestral populations onto maize or another cultivated species (e.g. sorghum). A previous study using inbred laboratory strains revealed that the two species differ in their oviposition choices in maize-mugwort tests. We sampled four natural populations in France (two of each taxon) and tested their oviposition behaviour toward four of their main host plant species: maize, sorghum, mugwort and hop. O. nubilalis females showed a very high preference for laying their eggmasses on maize, whereas O. scapulalis females displayed a more balanced range of preferences. O. nubilalis females were attracted slightly to sorghum, suggesting that this plant is an accidental, rather than a regular and ancestral host plant of O. nubilalis. One important result arising from this study is the significant proportion of eggs laid by both Ostrinia species on hop. This may explain why some stands of hop are sometimes not only infested by O. scapulalis but also by O. nubilalis larvae, a situation preventing assortative mating based on microallopatry. Hence, further studies must be conducted to see whether the host preference in the genus Ostrinia might be linked to assortative mating by a mechanism that is not mediated by the host plant.     

A physical map of the sorghum chloroplast genome

Summary The chloroplast genome of the IS1112C cytoplasm of sorghum was mapped by the construction of a Bam-HI library in pUC8, and hybridization with BamHI, SalI, and PstI digests of chloroplast DNA (ctDNA) of sorghum and maize. The molecules are extensively colinear, with only one of 13 SalI fragments differing slightly from maize. Seven of 70 restriction sites differed in the two species. A total molecular size of ca. 138 kb was estimated for sorghum. The inverted repeat was not conserved between sorghum and maize, as revealed by a slightly larger BamHI 16S rDNA fragment in sorghum. Homology of a sequence adjacent to the bcl gene and one end of the inverted repeat was detected. These homologies were also observed in maize, and suggest that the ctDNA genomes of sorghum and maize share small reiterations of sequences of the inverted repeat.USDA-ARS     

Color sensitivity in the receptive fields of neurons of the squirrel visual cortex

Color-opponent properties in neurons of the primary visual cortex were investigated in the squirrel. All neurons responded to the presentation of both black and white visual stimuli and of colored stimuli — mainly to blue and green. In 65% of test neurons a response only occurred when blue and green stimuli were applied while the remaining cells partially responded to red. Neurons were divided into groups according to how they responded to the presentation of stimuli composed of black and white: whether nonselective, directionally selective, or orientationally selective (simple or complex). No color-opponent properties were found in any of these groups at receptive field level. The whole or parts of the receptive field responded similarly to the presentation of white, blue, or green stimuli of the same shape. The way in which the receptive fields were divided into on- and off-regions and between directional and orientational selectivity does not depend on the color of the visual stimuli. Findings are discussed with regard to the presence of opponent-color cells in squirrel retina and lateral geniculate body.A. N. Severtsov Institute of Evolutionary Morphology and Animal Ecology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 17, No. 6, pp. 764–770, November–December, 1985.     

Comparative genetic mapping between duplicated segments on maize chromosomes 3 and 8 and homoeologous regions in sorghum and sugarcane

Comparative mapping within maize, sorghum and sugarcane has previously revealed the existence of syntenic regions between the crops. In the present study, mapping on the sorghum genome of a set of probes previously located on the maize and sugarcane maps allow a detailed analysis of the relationship between maize chromosomes 3 and 8 and sorghum and sugarcane homoeologous regions. Of 49 loci revealed by 46 (4 sugarcane and 42 maize) polymorphic probes in sorghum, 42 were linked and were assigned to linkage groups G (28), E (10) and I (4). On the basis of common probes, a complete co-linearity is observed between sorghum linkage group G and the two sugarcane linkage groups II and III. The comparison between the consensus sorghum/sugarcane map (G/II/III) and the maps of maize chromosomes 3 and 8 reveals a series of linkage blocks within which gene orders are conserved. These blocks are interspersed with non-homoeologous regions corresponding to the central part of the two maize chromosomes and have been reshuffled, resulting in several inversions in maize compared to sorghum and sugarcane. The results emphasize the fact that duplication will considerably complicate precise comparative mapping at the whole genome scale between maize and other Poaceae.     

Nucleotide sequence of the split tRNAleu(UAA) gene from Sorghum bicolor chloroplasts

The nucleotide (nt) sequence of the split tRNAleu(UAA) gene and 328 nt of its flanking regions from sorghum chloroplasts (cp) has been determined. This gene is located in the BamHI-6 fragment in a map position very similar to that of maize. The exon of sorghum tRNAleu gene has an identical nt sequence to its counterpart in maize. Although the 450 nt of intron in sorghum is 8 nt shorter than that of maize, the nt sequence between them shows 97% homology. Like maize and broad bean, the intron from sorghum cp tRNAleu gene could be folded into a secondary structure which is similar to the postulated structure of the intron from the auto-spliceable rRNA precursor of Tetrahymena. Both introns from sorghum and maize contain open reading frames (ORFs) which are conserved at the N terminus. The putative AUG initiation codon for both ORFs is located in the stem region of a 12-bp secondary structure of highly A + T-rich sequences.