The Biology of the Sudan Bollworm, Diparopsis watersi (Roths.), in the Gash Delta, Sudan

1958 ◽  
Vol 49 (1) ◽  
pp. 1-23 ◽  
Author(s):  
J. P. Tunstall
Keyword(s):  
Pupal Stage ◽  
Soil Surface ◽  
Climatic Conditions ◽  
Egg Laying ◽  
Cotton Crop ◽  
Soil Temperatures ◽  
History Of ◽  
Successive Generations ◽  
Two Peaks ◽  
Eastern Sudan

Diparopsis watersi (Roths.) is a serious pest of the cotton crop in the Gash Delta of the eastern Sudan. The climate and method of cotton cultivation are described briefly and a general account of the incidence of D. watersi during the season is given. Earlier work in the Sudan on this bollworm was mainly centred in the Northern Province and there is little information on the history of its occurrence in the Gash Delta. The aspects of its biology considered here include its egg-laying and larval habits, and duration of the pupal stage.The majority of eggs were laid on the younger and more accessible plant growth. The period of wandering in search of food after eclosion from the egg was of short duration with normal egg placement, the emerging larvae had little difficulty in finding suitable food, and mortality from failure to do so was low on healthy plants. Depth of pupation did not vary greatly with soil type; the majority of pupae were found within one inch of the soil surface, and none at a depth greater than three inches. Only when the soil was a heavy clay that had baked hard following the rains, did the emerging moths have difficulty in passing through it and ascending to the surface.The proportion of larvae forming diapause pupae increased amongst field-collected larvae as the season advanced, and in successive generations bred in an insectary from the non-diapause fractions of the preceding generations, but at no time was there a complete cessation in the production of non-diapause pupae and infestations persisted as long as there was actively growing cotton. This persistent activity in the Gash Delta is contrasted with the restriction of D. watersi to a six months' season in Nigeria. The emergence of moths from diapause pupae was not completed during the season following that of pupation, but extended for at least two further seasons; approximately 35 per cent, of the total diapause pupal population was still alive and present in the soil after the first season's emergence. In any one season the emergence was bimodal, the two peaks of emergence, which were of similar magnitude, occurring in September-October and mid-November to mid-January. When diapause pupae were kept in the laboratory and thus exposed to less extreme temperatures than in the field, the emergence was distinctly unimodal, with maximum emergence during September. The bimodal emergence observed in the field is considered to be a result of external environmental factors that inhibit pupal development at certain times of year, and emergence data from diapause pupae exposed to different climatic conditions suggest that high soil temperatures are such a factor. The pattern of moth emergence from diapause pupae in the Gash Delta is compared with that found in Nigeria and Nyasaland.Natural mortality of D. watersi is discussed, and certain larval parasites, notably an un-named species of Apanteles of the ultor Reinh. group, and Bracon brevicornis Wesm., are considered to be of importance.The study of the biology of D. watersi has emphasised the difficulties in controlling this bollworm, and stressed the importance of attempting to destroy it in the diapause state, preferably during the “ dead ” season. It is considered that mechanical cultivation, of the soil may provide a means to that end.

scholarly journals Bionomics of the African Apefly (Spalgis lemolea) as A Potential Natural Enemy of the Papaya Mealybug (Paracoccus marginatus) in Tanzania

2020 ◽  
Vol 12 (8) ◽  
pp. 3155
Author(s):  
Sayuni P. Nasari ◽  
Anna C. Treydte ◽  
Patrick A. Ndakidemi ◽  
Ernest R. Mbega
Keyword(s):  
Life Cycle ◽  
Natural Enemy ◽  
Pupal Stage ◽  
Petri Dish ◽  
Egg Laying ◽  
Potato Plants ◽  
Development Period ◽  
History Of ◽  
Males And Females ◽  
Blotter Paper

The African apefly (Spalgis lemolea Druce) is a potential natural enemy of the papaya mealybug (Paracoccus marginatus Williams and Granara de Willink). We studied the life history of apeflies in the laboratory at a temperature of 25–27 °C and a relative humidity of 55%–65% under a 12 h photoperiod condition. The papaya mealybugs and apefly larvae were collected from papaya plants in Tengeru, Arusha, Tanzania. The papaya mealybugs were introduced and allowed to multiply on potted sprouting potato plants in screened cages. In order to study the life cycle and predation of apeflies, an apefly egg was placed on an open screen-covered petri dish containing a moist blotter paper and observed for larva emergence. After the apefly larva emergence, a mixture of mealybug eggs (up to 1500), nymphs (200–250) and adults (100–150) was introduced in the petri dish each day and the consumption rate by the apefly larvae was quantified until the larvae reached pupal stage. Then, the apefly adults were collected and put into cages 30 cm × 30 cm × 30 cm containing cotton wool soaked in water, for observation of pre-mating, mating, egg-laying and life span. Results indicate that the apefly completed its life cycle in 23 days. The mean development period of the eggs was four days and the development period for the larva, pre-pupa, and pupa was nine, one and ten days respectively. The adult apefly emerged after 9 days of the pupa stage with mean body lengths of 10.1 ± 0.4 mm and 11.0 ± 0.8 mm for the males and females, respectively. The female laid an average of 68 eggs in groups of two to seven at different sites after 4–5 days of emergence. In this study one apefly larva was capable of consuming about 1983 ± 117, 123 ± 6 and 80 ± 9 papaya mealybug eggs, nymphs and adults respectively during larval stage. These results reveal the predatory potential of the apefly in suppressing the population of papaya mealybugs under field conditions.

Observations on the Life History of Onthophagous depressus (Coleoptera: Scarabaeidae)

1996 ◽  
Vol 31 (1) ◽  
pp. 63-71
Author(s):  
J. S. Hunter ◽  
G. T. Fincher ◽  
D. C. Sheppard
Keyword(s):  
Life History ◽  
Embryonic Development ◽  
Pupal Stage ◽  
Soil Surface ◽  
Cattle Dung ◽  
Brood Cell ◽  
Pupal Development ◽  
Adult Females ◽  
History Of ◽  
Southern Georgia

Adult Onthophagus depressus Harold constructed brood cells of cattle dung 15 to 30 cm below the soil surface. These brood cells averaged 23.1 mm long and 16.1 mm wide. Adult females deposited a single egg in the egg chamber of each brood cell. Eggs were 2.3 to 2.5 mm long and 1.1 to 1.4 mm wide. Embryonic development required 2.5 to 4.3 d; larval development (three instars) 27 d, and pupal development about 12 d. Development from egg to adult averaged 46.3 d at 25–27°C. Adult beetles were captured in all months except February with peak flight activity between 2000 and 2100 h (EST). Overwintering occurred in the adult and/or pupal stage in southern Georgia.

Studies on Wheat Bulb Fly, (Leptohylemyia coarctata, Fall.)

1946 ◽  
Vol 37 (2) ◽  
pp. 251-271 ◽  
Author(s):  
H. C. Gough
Keyword(s):  
Laboratory Experiment ◽  
Pupal Stage ◽  
Soil Surface ◽  
Egg Laying ◽  
Limited Area ◽  
Field Observations ◽  
Suitable Host

Laboratory and field observations have been made on the biology of Wheat Bulb Fly in the years 1943–45. The eggs hatch in late January and early February. Severe frosts delay hatching but do not kill the eggs. In a laboratory experiment a high proportion of eggs buried 18 inches below the soil surface, hatched, and the larvae infested plants. Field observations showed that proportions of the eggs also survive prolonged flooding.The development and habits of the larvae are recorded. It was confirmed that oats are not a suitable host and though a very small number of these plants were infested the larvae did not survive. Occasionally two larvae infest the same shoot and when this happens one larva dies. The larvae leave the plants in April or early May and pupate in the soil. The pupal stage lasts six to seven weeks.The adults emerge, males first, in June. Copulation occurs about three weeks after emergence and at this time dense aggregations of flies occur. Usually males predominate in these and in certain circumstances all the flies are males. The flies disperse gradually from the field in which they emerged and the females start laying eggs in suitable areas about a month after emergence. In Yorkshire egg laying occurred in July and early August and lasted about a month. Even within the limited area and time of these observations variations up to three weeks were noted in different places and seasons. Lateness was associated with heavy soils.

scholarly journals Impact of Row Spacing and Planting Date on the Canopy Environment, Abundance of Lesser Cornstalk Borer and Other Arthropods, and Incidence of Aflatoxigenic Fungi in Peanuts

1997 ◽  
Vol 24 (1) ◽  
pp. 52-59
Author(s):  
S. D. Stewart ◽  
K. L. Boweri ◽  
T. P. Mack ◽  
J. H. Edwards
Keyword(s):  
Climatic Conditions ◽  
Planting Date ◽  
Row Spacing ◽  
Planting Dates ◽  
Canopy Development ◽  
Late Planting ◽  
Elasmopalpus Lignosellus ◽  
Soil Temperatures ◽  
Lepidoptera Pyralidae ◽  
Wide Row Spacing

Abstract Three row spacings and two planting dates for peanuts, Arachis hypogaea L., were examined in 1993 and 1994 to determine the influence of the canopy environment on lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae), other arthropods, and alflatoxigenic fungi. Climatically, 1993 and 1994 were disparate years. Decreasing row spacing increased relative leaf area and light interception by the canopy but, compared to difference between planting dates or years, had a relatively small impact on soil temperatures and relative humidity within the canopy. Late planting produced smaller plants, retarded canopy development, and reduced yield in both years, but especially in 1993 when it was hot and dry. The wide row spacing did not yield as well as twin and normal row spacings in either year. Lesser cornstalk borer damage and aflatoxin concentration were higher in the late planting than in the early planting of 1993, but were unaffected by row spacing. Fewer predatory arthropods were caught as row spacing decreased in both beat and pitfall samples, but planting date had variable effects. Prevailing climatic conditions and planting date appeared to be more important in influencing the canopy environment and pest densities than was row spacing.

Late-glacial and Post-glacial history of the Chalk escarpment near Brook, Kent

1964 ◽  
Vol 248 (745) ◽  
pp. 135-204 ◽  
Keyword(s):  
Bronze Age ◽  
Iron Age ◽  
Late Glacial ◽  
Climatic Conditions ◽  
Valley Floor ◽  
Glacial Period ◽  
Late Neolithic ◽  
Local Conditions ◽  
Arable Farming ◽  
History Of

This paper describes the morphology of a small piece of the Chalk escarpment near Brook in east Kent, and reconstructs its history since the end of the Last Glaciation. The escarpment contains a number of steep-sided valleys, or coombes, with which are associated deposits of chalk debris, filling their bottoms and extending as fans over the Gault Clay plain beyond. Here the fans overlie radiocarbon-dated marsh deposits of zone II (10 000 to 8800 B.C.) of the Late-glacial Period. The debris fans were formed and the coombes were cut very largely during the succeeding zone III (8800 to 8300 B.C.). The fans are the products of frost-shattering, probably transported by a combination of niveo-fluvial action and the release of spring waters; intercalated seams of loess also occur. The molluscs and plants preserved in the Late-glacial deposits give a fairly detailed picture of local conditions. The later history of one of the coombes, the Devil’s Kneadingtrough, is reconstructed. The springs have effected virtually no erosion and have probably always emerged more or less in their present position. In the floor of the coombe the periglacial chalk rubbles of zone III are covered by Postglacial deposits, mainly hillwashes. They are oxidized and yield no pollen, but contain rich faunas of land Mollusca, which are presented in the form of histograms revealing changing local ecological and climatic conditions. During most of the Post-glacial Period, from the end of zone III until about the beginning of zone VIII, very little accumulation took place on the coombe floor. But below the springs there are marsh deposits which span much of this interval. They yield faunas of considerable zoogeographical interest. The approximate beginning of zone VII a (Atlantic Period) is reflected by a calcareous tufa, which overlies a weathering horizon, and represents an increase in spring flow. Two clearance phases are deduced from the molluscan record. The first may have taken place at least as early as the Beaker Period (Late Neolithic/earliest Bronze Age); the second is probably of Iron Age ‘A’ date. In Iron Age times the subsoil was mobilized and a phase of rapid hillwashing began. As a result the valley floor became buried by humic chalk muds. The prime cause of this process was probably the beginning of intensive arable farming on the slopes above the coombe; a possible subsidiary factor may have been the Sub-Atlantic worsening of climate. The muds yield pottery ranging in date from Iron Age ‘Kentish first A’ ( ca . 500 to ca . 300 B.C.) to Romano-British ware of the first or second centuries A.D. Evidence is put forward for a possible climatic oscillation from dry to wet taking place at about the time of Christ. In the later stages of cultivation, possibly in the Roman Era, the valley floor was ploughed and given its present-day form.

Biology and natural history of Caladenia

2009 ◽  
Vol 57 (4) ◽  
pp. 247 ◽  
Author(s):  
Kingsley Dixon ◽  
Raymond L. Tremblay
Keyword(s):  
Natural History ◽  
Arid Zone ◽  
Secondary Infection ◽  
Soil Surface ◽  
Growth Cycle ◽  
Cortical Cells ◽  
Herbaceous Perennials ◽  
Terrestrial Orchids ◽  
History Of ◽  
Soil Wetting

The genus Caladenia comprises species that exhibit remarkable consistency in terms of growth form and phenological patterns. All taxa are herbaceous perennials, with the shoot arising annually from a single, usually spheroid, tuber and producing a single, hairy leaf. The tuber is annually replaced either side-by-side with the parent tuber or terminating a descending structure known as a dropper. The dropper is a depth-seeking mechanism that enables placement of the tuber at depth in the soil as a means to avoid predation by surface-foraging native mammals or away from the high temperatures and desiccating conditions during summer dormancy. The 3--5 attenuated roots produced at the junction between the tuber and shoot and produced late in the growing cycle and devoid of mycorrhiza suggest their functional significance may relate to water uptake. Mycorrhizal endophytes are confined to a hypertrophic stem region at the soil surface (collar) subtending the leaf that positions the collar directly in the organically rich zone at the soil surface. This morphology is a unique characteristic of several Australasian orchids in the tribe Diuridae. Mycorrhizal infection occurs rapidly, with maximum colonisation in concert with the onset of breaking rains. Pelotons are restricted to cortical cells, with fully developed pelotons throughout infected tissues within a week or so of soil wetting. Infection occurs as a ‘once-off’ event, with little evidence of secondary infection later in the growth cycle and no evidence of peloton digestion. Some taxa utilise vegetative propagation, often leading to localised clustering as for taxa in the ‘filamentosa’ complex or, extensive clonal mats as found in Caladenia flava and C. latifolia where daughter tubers are produced at the end of extending horizontal outgrowths. For the majority of taxa, plants remain dry-season (summer) dormant from a few months up to 7 months for arid-zone taxa, with shoot emergence from the tuber of temperate species thought to occur in response to a drop in the mean minimum temperature. Pollination biology of Caladenia is apparently through a process of deception, either as food or sexual mimics, with some taxa engaging in self-pollination. Here we review the natural history of Caladenia and acknowledge that much of our understanding is based on assumptions of the biology of terrestrial orchids in general and emphasise areas of research and biological enquiry that will be critical in the development of an effective conservation program for the genus.

scholarly journals Crop residues on short-term CO2 emissions in sugarcane production areas

2013 ◽  
Vol 33 (4) ◽  
pp. 699-708 ◽  
Author(s):  
Mariana M. Corradi ◽  
Alan R. Panosso ◽  
Marcílio V. Martins Filho ◽  
Newton La Scala Junior
Keyword(s):  
Co2 Emissions ◽  
Field Experiments ◽  
Crop Residues ◽  
Soil Surface ◽  
Dry Mass ◽  
Agricultural Crop ◽  
Short Term ◽  
Sugarcane Production ◽  
Soil Temperatures ◽  
Production Areas

The proper management of agricultural crop residues could produce benefits in a warmer, more drought-prone world. Field experiments were conducted in sugarcane production areas in the Southern Brazil to assess the influence of crop residues on the soil surface in short-term CO2 emissions. The study was carried out over a period of 50 days after establishing 6 plots with and without crop residues applied to the soil surface. The effects of sugarcane residues on CO2 emissions were immediate; the emissions from residue-covered plots with equivalent densities of 3 (D50) and 6 (D100) t ha-1 (dry mass) were less than those from non-covered plots (D0). Additionally, the covered fields had lower soil temperatures and higher soil moisture for most of the studied days, especially during the periods of drought. Total emissions were as high as 553.62 ± 47.20 g CO2 m-2, and as low as 384.69 ± 31.69 g CO2 m-2 in non-covered (D0) and covered plot with an equivalent density of 3 t ha-1 (D50), respectively. Our results indicate a significant reduction in CO2 emissions, indicating conservation of soil carbon over the short-term period following the application of sugarcane residues to the soil surface.

scholarly journals Seasonal emergence of selected summer annual weed species in dependence on soil temperature

2010 ◽  
Vol 56 (No. 9) ◽  
pp. 444-450 ◽  
Author(s):  
M. Jursík ◽  
J. Holec ◽  
J. Soukup ◽  
V. Venclová
Keyword(s):  
Chenopodium Album ◽  
Soil Surface ◽  
Main Field ◽  
Weed Species ◽  
Soil Temperatures ◽  
Field Emergence ◽  
The Relationship ◽  
Galinsoga Ciliata ◽  
Surface Layer Temperature ◽  
Mass Field

This study aimed to describe emergence cycles of selected weed species under Central European conditions in relation to cumulative soil temperatures from the start of the vegetation season. Emergence of Chenopodium album, Echinochloa crus-galli, Galinsoga ciliata, and Abutilon theophrasti was observed from March to October during the period 2001–2006 at two locations. The beginning of main field emergence was determined as the day when the sum of effective hour temperatures was achieved, and was detected from the second decade of April to early May for C. album, in the second decade of May for E. crus-galli, from late April to the beginning of May for G. ciliata, and from the end of April to mid-May for A. theophrasti. The relationship between cumulative soil surface layer temperature and weed mass field emergence at the beginning of the growing season is very direct (differences ±7 days) – but only when soil moisture is sufficient. In a drier spring, the beginning of mass field emergence occurs with 1–4 weeks of delay and field emergence is usually slower and protracted.

Effects of some crop management practices on reproduction of Meloidogyne javanica on Brassica napus

Nematology ◽  
2002 ◽  
Vol 4 (3) ◽  
pp. 381-386
Author(s):  
Christopher Steel ◽  
John Kirkegaard ◽  
Rod McLeod
Keyword(s):  
Brassica Napus ◽  
Soil Temperature ◽  
Egg Production ◽  
Management Practices ◽  
Seedling Emergence ◽  
Meloidogyne Javanica ◽  
Egg Laying ◽  
Infested Soil ◽  
Young Females ◽  
Soil Temperatures

AbstractThe effects of seed treatments with pesticides, soil temperature at sowing, cutting of plants with and without glyphosate herbicide, root disruption and age of crop at inoculation on reproduction of Meloidogyne javanica on Brassica napus were investigated. When inoculated at sowing, plants grown from fodder rape cv. Rangi seed treated with fenamiphos (0.35 g a.i. per 100 g) and from fodder swede cv. Highlander seed with a coating including imidacloprid had fewer galls than plants from seed untreated or treated with omethoate (0.7 g a.i. per 100 g). When nematode inoculation was delayed until 4 weeks after sowing, omethoate and the imadacloprid treatments had no effect while fenamiphos (0.7 g a.i. per 100 g seed) suppressed galling but also impaired seedling emergence and induced chlorosis. Green manure rape plants cvs Rangi and Humus transplanted into infested soil in the field in mid-autumn (soil temperature 17°C) remained nematode and gall-free, but tomato cv. Grosse Lisse plants were heavily galled. All three cultivars were gall-free when transplanted and grown in early winter (soil temperatures 8-14°C). Cutting off the tops of cv. Rangi plants at from 6 to 11 weeks after sowing and inoculation had no effect on egg production compared to that on intact plants. Predominant nematode stages in cut plants ranged from developing juveniles to egg-laying females. Application of glyphosate to freshly cut stems had no effect on egg production at any stage. Infesting soil with roots of cv. Rangi, finely chopped while nematodes in them were still juveniles, resulted in a low incidence of infection of bioassay tomato plants compared with infesting soil with rape roots chopped later, when females and females with eggs predominated. Young females in tomato roots laid eggs despite fine chopping of the roots. When cv. Rangi plants were inoculated at 3, 5 and 7 weeks after sowing, the 7-week-old plants were the least invaded and fewer eggs were produced on the 5 and 7-week-old plants than on the 3-week-old ones.

Natural history of a plant trait: branch-system abscission in Paleozoic conifers and its environmental, autecological, and ecosystem implications in a fire-prone world

Paleobiology ◽  
10.1666/12030 ◽  
2013 ◽  
Vol 39 (2) ◽  
pp. 235-252 ◽  
Author(s):  
Cindy V. Looy
Keyword(s):  
Fire Regime ◽  
Climatic Conditions ◽  
Early Permian ◽  
North Central ◽  
Seasonally Dry ◽  
Plant Trait ◽  
Branch System ◽  
Central Texas ◽  
History Of ◽  
Biotic Disturbance

Within conifers, active abscission of complete penultimate branch systems is not common and has been described mainly from juveniles. Here I present evidence for the abscission of penultimate branch systems within early so-called walchian conifers—trees with a plagiotropic branching pattern. The specimens studied originate from a middle Early Permian gymnosperm-dominated flora within the middle Clear Fork Group of north-central Texas. Complete branch systems of three walchian conifer morphotypes are preserved; all have pronounced swellings and smooth separation faces at their bases. The source plants grew in a streamside habitat under seasonally dry climatic conditions. The evolution of active branch abscission appears to correspond to an increase in the size of conifers, and this combination potentially contributed to the restructuring of conifer-rich late Paleozoic landscapes. Moreover, trees shedding branch systems and producing abundant litter have the potential to affect the fire regime, which is a factor of evolutionary importance because wildfires must have been a source of frequent biotic disturbance throughout the hyperoxic Early Permian.

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