咸宁地区桔全爪螨与天敌种群动态的初步研究

咸宁地区桔全爪螨与天敌种群动态的初步研究甘宗义,王盛桃（湖北省农科院果树茶叶研究所,武昌４３０２０９）ＰｏｐｕｌａｔｉｏｎＤｙｎａｍｉｃｓｏｆＣｉｔｒｕｓＲｃｄＭｉｔｅ（ＰａｎｏｎｙｃｈｕｓｃｉｔｒｉＭｃＧ．）ａｎｄＩｔｓＮａｔｕｒａｌＥｎｅｍｉｅｓ...     

Self-selection of an optimum diet from a mixture of wheat fractions by the larvae of Tribolium confusum

Tribolium confusum was reared from the beginning of the first instar to the pupa on wheat bran, endosperm or germ or on a 1 : 1 : 1 mixture of these three fractions. The food intake of the larvae reared on the mixture included more or less similar proportions of the three wheat fractions, averaging 1·5 per cent bran, 17·1 per cent endosperm and 81·4 per cent germ. Past work on the nutrition of stored-product insects has involved the assumption that the insects cannot feed selectively from a finely powdered diet. Our findings show that this assumption may not be warranted. The mixed diet supported growth better than any one of the pure fractions or any wheat diet previously tested by us. It was superior to germ, the best of the pure fractions, because it was more digestible and because the digested portion was more efficiently utilized for growth. Endosperm, the poorest diet of the fractions, was highly digestible but was not efficiently utilized. Bran, better than endosperm but inferior to germ, was relatively indigestible although the digested portion was efficiently utilized. Germ was both digestible and efficiently utilized.     

Role of granivory and insectivory in the life cycle of the carabid beetle Amara similata

1. The cereal field carabid beetle Amara similata was selected to elucidate the role of seeds and insects as food sources. Three experiments were performed to rank different weed seeds and insects in terms of food value: (i) fecundity in relation to adult diet, (ii) larval survival in relation to diet and (iii) larval survival in relation to parental diet.
2. Seeds were found to be of high value and insects of low value both for adults and larvae. Adding insects to a seed diet gave no significant improvement. The value of single species of seeds varied within adults and larvae, but also between adults and larvae. This is the first report that Amara larvae are granivorous.
3. The value of different insects varied by species. Cereal aphid species were of the lowest value both for adult and larval beetles. On a diet of mixed insects, the adults were able to produce a low number of eggs but the larvae all died before pupation.
4. There was no simple relation between survival of the larvae and the quality of the parents' diet.     

Food level reaction norms in size-selected milkweed bugs (Oncopeltus fasciatus)

Abstract. 1. The hypothesis that the small size of nonmigratory milkweed bugs from Puerto Rico (relative to large migratory bugs from Iowa) might be an adaptation to low food levels was tested with bugs selected for large and small size as the consequence of positive genetic correlation between body size and wing length. The test involved examining reaction norms of life history traits to different food levels.
2. When nymphs were reared on 3 milkweed seeds per nymph from hatch to adult eclosion, large bugs were adversely affected with only 50% and 60% in each of two replicates reaching adulthood. Control (unselected) and small bugs, however, were unaffected at this food level. None of the lines was affected at levels of 6 and 12 seeds per nymph.
3. When adults were reared from eclosion on 12, 18 or 24 milkweed seeds per bug, large bugs were adversely affected relative to control and small bugs at all three food levels. At each food level fewer large bugs produced eggs than either small or control bugs which did not differ.
4. The evidence from the food level reaction norms suggests that larger bugs will be selected against during periods of food shortage of the sort likely to occur in Puerto Rico.     

Habitat utilization by sympatric arctic charr Salvelinus alpinus L. and brown trout Salmo trutta L. in Lake Atnsjø, south-east Norway

SUMMARY. 1. Habitat utilization, as well as inter- and intraspecific relations of different size groups of arctic charr (Salvelinus alpinus (L.)) and brown trout (Salmo trutta L.) in Lake Atnsjø, south-east Norway, were investigated by analysing food and spatial niches from monthly benthic and pelagic gillnet catches during June-October 1985.
2. Small individuals (150–230 mm) of both arctic charr and brown trout occurred in shallow benthic habitats. However, they were spatially segregated as arctic charr dominated at depths of 5–15 m and brown trout at depths of 0–5 m.
3. Larger (>230 mm) arctic charr and brown trout coexisted in the pelagic zone. Both species occurred mainly in the uppermost 2-3 m of the pelagic, except in August, when arctic charr occurred at high densities throughout the 0–12 m depth interval. On this occasion, arctic charr were segregated in depth according to size, with significantly larger fish in the top 6 m. This was probably due to increased intraspecific competition for food.
4. The two species differed in food choice in both habitats, Arctic charr fed almost exclusively on zooplankton, whereas brown trout had a more variable diet, consisting of surface insects, zooplankton. aquatic insects and fish.
5. The data suggest that the uppermost pelagic was the more favourable habitat for both species. Large individuals having high social position occupied this habitat, whereas small individuals lived in benthic habitat where they were less vulnerable to agonistic behaviour from larger individuals and less exposed to predators. The more aggressive and dominant brown trout occupied the more rewarding part of the benthic habitat.     

Swarming behaviour in the Australian beetle, Heteronyx obesus, with notes on related species

Abstract. (1) Heteronyx obesus swarmed about twice annually on evenings when relative humidity was > 80% and temperature was at or above 20°C at 19.30 hours local time.
(2) Swarms were characterized by the frenzied, random flight of their component insects, and the clustering of males about females on vertical structures.
(3) Early the following morning beetles searched for pasture containing favoured food plants, and then burrowed into the soil near them.
(4) Adults did not ingest food before, during or for several days after swarming; the oesophagus and crop of all insects dissected was distended with gas, probably air. This condition appeared to be associated with pre-flight behaviour of individuals.
(5) The post-swarm activity was concerned with feeding, dispersal, maturation of eggs and oviposition.
(6) The distribution of individuals of the next generation was strongly influenced by presence in the sward of favoured food (sorrel, Rumex species) of the adults.     

Optimal number of matings in two aphidophagous ladybirds

Abstract.  1. The present study was designed to identify the optimal number of matings required for maximum fecundity and egg viability in two aphidophagous ladybirds, Cheilomenes sexmaculata and Propylea dissecta .
2. For this purpose, ladybirds were subjected to different numbers of matings and the reproductive responses were recorded thereafter.
3. The Gompertz model was used to draw asymptotic graphs for fecundity and per cent egg viability in both ladybird species. Ninety-five per cent and 50% of maximum theoretical fecundity and per cent egg viability were predicted from the model.
4. Ninety-five per cent maximum theoretical fecundity was obtained after 13.25 and 12.95 matings in C. sexmaculata and P. dissecta , respectively; and 8.95 and 11.25 matings were required for 95% maximum theoretical per cent egg viability in C. sexmaculata and P. dissecta , respectively.
5. The results of these experiments clearly support the existence of an optimal number of matings in these two ladybird species leading to maximum adult fitness.     

SOME PROPERTIES OF ISOLATED NEURONAL CELL FRACTIONS

Abstract— 1. Histochemical evidence was presented illustrative of the composition of neuronal and neuropil ('glial') fractions isolated according to a previously published procedure. The neuropil refers to all cortical tissue other than neuronal perikarya.
2. On the basis of cell counts and of DNA content, an average cell mass of 100-110 pg was calculated for cells in the neuronal fraction. Eight per cent of the total DNA was recovered in the neuronal fraction.
3. Both fractions synthesized ATP in vitro. Concentrations after 60 min incubation with glucose were: neuropil, 7–36 μmoles/mg protein; neuronal, 12–31 μmoles/mg protein.
4. Osmotic shock or homogenization resulted in changes in turbidity of the cell fractions which were interpreted as indicative of loss of cell structure. The free pool amino acids glutamate, glutamine, GABA, aspartate and alanine were retained in the precipitable material through several washes with isotonic solutions. Homogenization released 72 per cent of the neuronal and 68 per cent of the neuropil amino acids into the supernatant, but only 37 per cent and 19 per cent respectively of the protein.
5. By contrast with earlier reports, K⁺ accumulation has now been demonstrated in both neuronal and neuropil fractions. After incubation with glucose, K⁺ level were calculated as being 80 per cent of slice in the neuronal, and 65 per cent in the neuropil fraction. These results, and those of the osmotic shock experiments, were taken as indicative of the retention of some cell structure.
6. By comparison, cell fractions prepared by other procedures, using acetone-glycerol-water or tetraphenylboron for tissue disaggregation, produced preparations with limited metabolic capabilities; oxygen uptake, CO₂ and lactate production were all lowered substantially.     

Relation of oxygen consumption to size and temperature in desert arthropods

Abstract. 1. Oxygen consumption was determined for ninety-three taxa of desert-inhabiting arthropods of various life stages over the temperature range 10–40C. Regression analysis of O₂ consumed/individual/h on the mean dry weight of individual adult insects yielded a slope of 0.70 ( r = 0.87) while the same analysis for non-insect arthropods gave a slope of 0.74 ( r - 0.87).
2. Average Q₁₀ for all insects was 2.16 ± 0.66 over the 10–40C temperature range. Q₁₀was not significantly different among orders of arthropods at each 10 temperature interval but decreased significantly with an increase in temperature.
3. Per cent water content ranged from a mean of 60% for Coleoptera to 78% for Lepidoptera larvae and indicated the necessity of using dry weight values in analyses of the relationship between size and oxygen consumption rates.
4. Models are supplied for each taxon to calculate the minimum energy for basic metabolism of field populations per unit time and area.     

ON THE GROWTH AND RESPIRATION OF SULFUR-OXIDIZING BACTERIA

1. It is shown that Sulfomonas thiooxidans oxidizes elementary sulfur completely to sulfuric acid. Sodium thiosulfate is oxidized by this organism completely to sulfate. Sulfomonas thiooxidans differs, in this respect, from various other sulfur-oxidizing bacilli which either produce elementary sulfur, from the thiosulfate, or convert it into sulfates and persulfates. 2. The organism derives its carbon from the CO₂ of the atmosphere, but is incapable of deriving the carbon from carbonates or organic matter. 3. The S:C, or ratio between the amount of sulfur oxidized to sulfate and amount of carbon assimilated chemosynthetically from the CO₂ of the atmosphere, is, with elementary sulfur as a source of energy, 31.8, and with thiosulfate 64.2. The higher ratio in the case of the thiosulfate is due to the smaller amount of energy liberated in the oxidation of sulfur compound than in the elementary form. 4. Of the total energy made available in the oxidation of the sulfur to sulfuric acid, only 6.65 per cent is used by the organism for the reduction of atmospheric CO₂ and assimilation of carbon. 5. Sulfates do not exert any injurious effect upon sulfur oxidation by Sulfomonas thiooxidans. Any effect obtained is due to the cation rather than the sulfate radical. Nitrates exert a distinctly injurious action both on the growth and respiration of the organism. 6. There is a definite correlation between the amount of sulfur present and velocity of oxidation, very similar to that found in the growth of yeasts and nitrifying bacteria. Oxidation reaches a maximum with about 25 gm. of sulfur added to 100 cc. of medium. However, larger amounts of sulfur have no injurious effect. 7. Dextrose does not exert any appreciable injurious effect in concentrations less than 5 per cent. The injurious effect of peptone sets in at 0.1 per cent concentration and brings sulfur oxidation almost to a standstill in 1 per cent concentration. Dextrose does not exert any appreciable influence upon sulfur oxidation and carbon assimilation from the carbon dioxide of the atmosphere. 8. Sulfomonas thiooxidans can withstand large concentrations of sulfuric acid. The oxidation of sulfur is affected only to a small extent even by 0.25 molar initial concentration of the acid. In 0.5 molar solutions, the injurious effect becomes marked. The organism may produce as much as 1.5 molar acid, without being destroyed. 9. Growth is at an optimum at a hydrogen ion concentration equivalent to pH 2.0 to 5.5, dropping down rapidly on the alkaline side, but not to such an extent on the acid, particularly when a pure culture is employed. 10. Respiration of the sulfur-oxidizing bacteria can be studied by using the filtrate of a vigorously growing culture, to which a definite amount of sulfur is added, and incubating for 12 to 24 hours.     

Effects of neonate size and food concentration on the life history responses of a clone of the hybrid Daphnia hyalina × galeata to fish kairomones

1. The influence of fish kairomones on the life history parameters of a clone of the hybrid Daphnia galeata × hyalina was measured in laboratory experiments with small and large neonates at one food concentration. The influence of fish kairomones on neonates of the same size at two food concentrations was also investigated.
2. Neonate size (maternal investment per egg) changed the influence of fish kairomones on life history parameters. Daphnids that were small at birth showed greater differences between fish (kairomones present) and no-fish (kairomones absent) treatments for age at maturity and number of eggs in the first clutch than animals that were large at birth. On the other hand, animals that were large at birth differed more in size at maturity between fish and no-fish treatments than small neonates.
3. The food concentrations used in the experiments (0.25–0.75 mg C l^–1) hardly affected the influence of fish kairomones on the life history characteristics studied.
4. The effect of fish kairomones on the size of neonates from the first clutch was similar for large and small daphnids. In the no-fish treatment significant differences were found between small and large neonates for age at maturity and number of eggs in the first clutch. In the fish treatment size at maturity differed significantly between small and large neonates.
5. In life history experiments, neonate size has to be taken into account when measuring the effects of fish kairomones because size at birth influences the results.     

Effects of neonate size and food concentration on the life history responses of a clone of the hybrid Daphnia hyalina × galeata to fish kairomones

1. The influence of fish kairomones on the life history parameters of a clone of the hybrid Daphnia galeata × hyalina was measured in laboratory experiments with small and large neonates at one food concentration. The influence of fish kairomones on neonates of the same size at two food concentrations was also investigated.
2. Neonate size (maternal investment per egg) changed the influence of fish kairomones on life history parameters. Daphnids that were small at birth showed greater differences between fish (kairomones present) and no-fish (kairomones absent) treatments for age at maturity and number of eggs in the first clutch than animals that were large at birth. On the other hand, animals that were large at birth differed more in size at maturity between fish and no-fish treatments than small neonates.
3. The food concentrations used in the experiments (0.25–0.75 mg C l^–1) hardly affected the influence of fish kairomones on the life history characteristics studied.
4. The effect of fish kairomones on the size of neonates from the first clutch was similar for large and small daphnids. In the no-fish treatment significant differences were found between small and large neonates for age at maturity and number of eggs in the first clutch. In the fish treatment size at maturity differed significantly between small and large neonates.
5. In life history experiments, neonate size has to be taken into account when measuring the effects of fish kairomones because size at birth influences the results.     

Seed growth suppression constrains the growth of seed parasites: premature acorn abscission reduces Curculio elephas larval size

Abstract.  1. The abscission of seeds infested by insects is common in many plants and has been proposed as a defensive mechanism, although its negative consequences for insects have rarely been assessed.
2. We assessed the consequences of seed abscission studying the interactions between the holm oak Quercus ilex and the chestnut weevil Curculio elephas , its main pre-dispersal seed predator. Female weevils oviposit into the acorns and the larvae must complete their development inside a single acorn feeding on the cotyledons. The growth of the infested acorns is suppressed because they are prematurely abscised.
3. Female weevils oviposit along the acorn growing period; hence, the size of the infested acorns increased with date. The growth of the larvae inside the smaller, early infested, acorns was constrained because food (i.e. cotyledons) was frequently depleted. Larval size increased with the date along with the size of the infested acorns, but it declined slightly in the latest dates as a result of the higher conspecific competition provoked by the larger number of larvae per acorn.
4. The present results demonstrate that premature seed abscission by Q. ilex had negative consequences for C. elephas , as a smaller acorn size reduced food availability and constrained larval size, a key insect life history trait. At the same time, it is suggested that the growth suppression of infested acorns may condition the oviposition phenology of these insects according to their body size. These results need to be considered in further research in the context of the evolutionary significance of premature seed abscission as a defensive mechanism.     

A minimalist approach to the effects of density-dependent competition on insect life-history traits

Abstract  1. Due to its effects on the phenotypic and genotypic expression of life-history traits, density-dependent competition is an important factor regulating the growth of populations. Specifically for insects, density-dependent competition among juveniles is often associated with increased juvenile mortality, delayed maturity, and reduced adult size.
2. The aim of the work reported here was to test whether the established phenotypic effects of density-dependent competition on life-history traits could be reproduced in an experimental design requiring a minimal number of individuals. Larvae of the mosquito Aedes aegypti were reared at densities of one, two, or three individuals per standard Drosophila vial and in six different conditions of larval food availability. This design required relatively few individuals per independent replicate and included a control treatment where individuals reared at a density of one larva per vial experienced no density-dependent interactions with other larvae.
3. Increased larval densities or reduced food availability led to increased larval mortality, delayed pupation, and the emergence of smaller adults that starved to death in a shorter time (indicating emergence with fewer nutritional reserves).
4. Female mosquitoes were relatively larger than males (as measured by wing length) but males tended to survive for longer. These differences increased as larval food availability increased, indicating the relative importance of these two traits for the fitness of each sex. The role of nutritional reserves for the reproductive success of males was highlighted in particular.
5. This minimalist approach may provide a useful model for investigating the effects of density-dependent competition on insect life-history traits.     

Triangular fecundity function and ageing in ladybird beetles

Abstract 1. In insects, the age schedules of fecundity tend to be triangular and this has been attributed more to temporal patterns of mortality than to fecundity. The objective of the work reported here was to test the assumption that senescence shapes the fecundity function in ladybird beetles, and in particular that the production function declines with age.
2. The results of a laboratory study on three species of predatory ladybird beetle indicated that the efficiency with which these insects acquire and process food declined with age. Although supplied with the same amount of food each day, after the onset of reproduction, these beetles ate less and less with increasing age. Egg production mirrored the decline in aphid consumption. Associated with this was a decline in fertility, assimilation, and speed of locomotion with age.
3. This study indicates that production declined with age and that this shaped the fecundity schedules in these ladybird beetles. In addition, the results indicated that ladybirds are income breeders and, as predicted, the reproductive effort of the small species was greater than that of the large species used in this study.     

Epilithic bacteria in an acid and a calcareous headstream

SUMMARY. 1. Environmental variables and epilithic bacteria on small stones were monitored during summer and winter in Burbage Brook and the River Lathkill, two headstreams in the Derbyshire Peak District.
2. Burbage Brook was usually near-neutral in summer, but acid in winter; the River Lathkill was circumneutral throughout the year.
3. In summer, epilithic bacteria showed few between-stream differences. In winter, however, total bacteria, colony-forming units, per cent chromogenic colony-forming units, per cent viable bacteria, V_max for glucose mineralization and V_max/bacterium were all significantly less in the acid Burbage Brook.
4. Inhibition of epilithic bacteria in Burbage Brook was also observed when pH fell to a low level during a summer spate.
5. Multiple-regression analysis confirmed that epilithic bacteria were less successful at low pH but also suggested that pH was not the only environmental variable to influence epilithic bacteria. Especially notable were positive relationships with density of epilithic chlorophyll a and temperature in Burbage Brook and with chlorophyll a in the River Lathkill.     

Consequences of tadpole shrimp predation on mayflies in some Californian ponds

SUMMARY. 1. During two, 1-month studies, the abundance of mayfly nymphs, Callibaetis californicus Banks, in small ponds that contained the tadpole shrimp, Triops longicaudatus (LeConte), often was significantly lower than in ponds without tadpole shrimps. Mayfly abundance was either positively correlated or not significantly associated with that of predacious insects.
2. Larger mayfly nymphs were a greater fraction of the population in ponds with Triops than in ponds without tadpole shrimps. Between 2 and 3 weeks after ponds were flooded, the smallest mayfly nymphs were absent from ponds in which T. longicaudatus densities were >5 individuals per square metre during the summer and >15 individuals per square metre during the autumn.
3. In prey-choice trials, T. longicaudatus consumed predominantly small C. californicus nymphs (mean headwidth ± 1 SD: 0.44 ± 0.05 mm). After encounters with tadpole shrimps, small mayfly nymphs moved relatively shorl distances, were easily overtaken, and were, consequently, more susceptible to tadpole shrimps than larger-sized nymphs.     

Microhabitat selection by a stream-dwelling amphipod: a muitivariate analysis approach

SUMMARY. 1. Colonization of microhabitat implants by the amphipod Gammarus pseudolimmnaeus in a small southern Ontario stream was studied in order to analyses the factors controlling habitat selection. The variables substrate particle size, current speed, presence of food and light were used in an analysis of covariance, with percentage weight of organic matter of silt and percentage interstitial space occluded by silt as the covariates.
2. Greatest numbers of amphipods settled on microhabitats featuring large substrate particles, no current and presence of food. There was also a positive relationship between total numbers and the volume of silt deposited on the microhabitats by the stream; small quantities of silt had a beneficial effect on colonization but larger quantities became detrimental.
3. The change from a positive effect occurred at approximately 25% occlusion of the interstitial space in large gravel ( diameter=3.2 cm) and at approximately 55% occlusion in small gravel ( diameter = 0.34 cm).
4. Large animals (6–16.0 mm long) were found predominantly in microhabitats featuring food and large substrate. Medium-sized animals (3–6.0 mm) were most commonly associated with no current and presence of food, and were positively affected by the amount of silt but, at the same time, were negatively affected by increasing occlusion of interstitial spaces by silt. Numbers of small Gammarus (<3.0 mm) were affected only by silt and in a similar manner to medium-sized animals.
5. Amphipod biomass was greatest in microhabitats featuring food and no current. Previous data on the behaviour of this species in laboratory stream-tanks are compared with the microhabitat selections seen.     

Arbuscular mycorrhizal fungi influence visitation rates of pollinating insects

Abstract.  1. Arbuscular mycorrhizal (AM) fungi can increase a number of plant traits to which pollinating insects are known to respond. These include total plant size, flower number, flower size, and amount of pollen produced.
2. It was hypothesised that these effects would lead to a different visitation rate of pollinating insects on mycorrhizal and non-mycorrhizal plants. To test this idea, three species of annual plants ( Centaurea cyanus , Tagetes erecta , and Tagetes patula ) were grown with and without AM fungi and the visits by pollinating insects were recorded over a 2-month period.
3. In all three species, mycorrhizal plants experienced a greater number of pollinator visits per flower per unit time. Diptera and Hymenoptera were the predominant insects and the latter order showed the strongest response.
4. Here, it is suggested that mycorrhizal fungi increase floral visitation rates by insects, but that the mechanism varies from one plant species to another. In C. cyanus , it appears to be due to flower number per plant, in T. patula it is individual inflorescence size, and in T. patula it is nectar standing crop per inflorescence.     

Diet and predation by three leaf-associated stoneflies (Plecoptera) in an Arkansas mountain stream

SUMMARY. 1. Life cycles, food habits, mouthpart morphologies, prey preferences, and predator-prey size relationships were investigated for the three most common stoneflies in leaf packs in the Little Missouri River, Arkansas: Clioperla clio (Newman), Isoperla namata Prison, and Perlesta spp. Each species was univoltine and had a fast seasonal cycle, with extended egg or nymphal diapause, rapid nymphal growth and emergence in spring to early summer.
2. Foregut analysis showed predictable dietary shifts by C. clio and Perlesta spp., from detritus and diatoms in early instars to invertebrate prey in later instars. Isoperla namata fed facultatively on insects, detritus and diatoms, with no conspicuous ontogenetic shifts. The mouthparts of all three species strongly reflected their diet.
3. Electivity analysis indicated opportunistic feeding by the three species, with feeding rarely differing significantly from random.
4. Sizes of stonefly predators and their ingested prey were highly correlated ( P <0.01). However, rather than shifting toward larger prey sizes, growing predators expanded their size thresholds and continued to include numerous small prey items in their diet. Prey choice was governed most directly by prey availability, because stoneflies selected the most abundant groups, irrespective of size or taxon.
5. The likelihood of competition among the three stoneflies for prey was minimized by timing of their life cycles, differential food use and probably the temporary nature of leaf pack habitats.