The use of ageing techniques to evaluate the effects of aerial spraying against Glossina morsitans centralis Machado (Diptera: Glossinidae) in northern Botswana

1978 ◽  
Vol 68 (3) ◽  
pp. 373-383 ◽  
Author(s):  
J. E. Davies
Keyword(s):  
Large Scale ◽  
Okavango Delta ◽  
Glossina Morsitans ◽  
Natural Conditions ◽  
Fluctuating Temperature ◽  
Delta Area ◽  
Pupal Period ◽  
Pregnant Females ◽  
Glossina Morsitans Centralis ◽  
Low Rate

AbstractDuring a large-scale air-spray trial using endosulfan against Glossina morsitans centralis Machado in the Okavango Delta area of Botswana, a programme of ageing all flies caught on fly-rounds was undertaken. The aim was to evaluate closely the effect of repeated sprays on the population and especially to determine the origin of the small residual population that often remains after spraying. Ageing males by the wing-fray method indicated that none survived the spraying. Ageing females by ovarian dissection showed that (a) no breeding occurred between sprays, (b) one pupal period was just covered by four spray applications, (c) the residual population was composed of females that had survived the spraying and (d) all survivors had been pregnant at the time of treatment. Dissections also showed a very low rate of insemination between sprays, but the few females that survived spraying were all inseminated. Larval and pupal periods under natural conditions of fluctuating temperature are discussed together with methods of improving air spraying results by eliminating pregnant females.

Aircraft applications of insecticides in East Africa

1961 ◽  
Vol 52 (2) ◽  
pp. 305-316 ◽  
Author(s):  
G. F. Burnett ◽  
D. Yeo ◽  
A. W. D. Miller ◽  
P. J. White
Keyword(s):  
Large Scale ◽  
Lethal Dose ◽  
Central Province ◽  
Cent Solution ◽  
Glossina Morsitans ◽  
Pregnant Females ◽  
The North ◽  
Reliable Performance ◽  
Median Diameter ◽  
Coarse Aerosol

SummaryIn the North Block at Chungai, comprising about 11 sq. miles of thorn savannah and thicket in Central Province, Tanganyika, an Auster J5G aircraft was used between July 1959 and March 1960 to apply a 2·5 per cent. solution of dieldrin in oil at the rate of 0·125 gal. per acre in an attempt to eradicate Glossina morsitans Westw. and G. pallidipes Aust. Eight applications were made at approximately four-weekly intervals. Swath width was 55 yd., and the aircraft emitted the insecticide as a coarse aerosol of volume median diameter 50–60μ as it flew in both directions over the block.The operation suffered delays, and three applications were incomplete to varying degrees. Kills of G. morsitans per application appeared to be 85 per cent. or higher, but the final reduction of 99·5 per cent. could theoretically have been attained with consecutive mortalities of only 65 per cent. It is suggested that this discrepancy may be due to the higher lethal dose required by pregnant females. G. pallidipes was also reduced by 99·5 per cent. Numbers of fly were reduced sufficiently for large-scale settlement with cattle, which should complete the work of exterminating the fly.The experiment is compared with that of the previous year in the same block, using γBHC, which reduced fly catches by less than 50 per cent. It is concluded that a combination of reduced swath width, greater volume dosage, more lethal insecticide and smaller lethal drop, together with improved flying technique and the more reliable performance of the disseminating equipment, was responsible for the improved result. It is thought that without delays, interruptions, incomplete applications and reinfestation, even better results would be obtained.This was the cheapest and one of the most successful aerial operations carried out against savannah tsetse. Costs actually over the ground were £301 per sq. mile; incidental costs due to the locality of operations were £66 per sq. mile. There is little chance of reducing the costs of flying directly, but economies are possible by the use of other insecticides or, more probably, by more efficient dispensing equipment.

scholarly journals Inconclusive evidence of sexual reproduction of invasive Halophila stipulacea: a new field guide to encourage investigation of flower and fruit production throughout its invasive range

2020 ◽  
Vol 63 (6) ◽  
pp. 537-540
Author(s):  
Fee O.H. Smulders ◽  
Kelcie L. Chiquillo ◽  
Demian A. Willette ◽  
Paul H. Barber ◽  
Marjolijn J.A. Christianen
Keyword(s):  
Sexual Reproduction ◽  
Clonal Growth ◽  
Large Scale ◽  
Fruit Production ◽  
Morphological Evidence ◽  
Invasive Range ◽  
Reproductive Structures ◽  
Halophila Stipulacea ◽  
The Caribbean ◽  
Low Rate

AbstractThe dioecious seagrass species Halophila stipulacea reproduces mainly through fast clonal growth, underlying its invasive behavior. Here, we provide morphological evidence to show that the first findings of fruits in the Caribbean were misidentified. Consequently, H. stipulacea reproduction is likely still only asexual in the Caribbean. Therefore, we introduce an identification key of H. stipulacea reproductive structures to encourage careful identification and quantification throughout its invasive range. Until large-scale seed production in invaded habitats is reported, the apparent low rate of sexual reproduction needs to be considered in current studies investigating the invasion capacity of this species.

The development characteristics of the discontinuous leader under the positive switching impulse with low rate of voltage rising

2018 ◽  
Vol 83 (2) ◽  
pp. 20802 ◽  
Author(s):  
Yaoheng Xie ◽  
Yue Yishi ◽  
Huisheng Ye ◽  
Liu Yun ◽  
Yongheng Zhong ◽  
...  
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Unit Length ◽  
Leader Development ◽  
Air Gap ◽  
Discharge Process ◽  
Temperature Changes ◽  
Channel Temperature ◽  
Impulse Voltage ◽  
Low Rate

Discontinuous leader development is the most important discharge process under the application of the switching impulse voltage with the low rate of voltage rising, which is of great significance to study the external insulation characteristics of ultra-high voltage (UHV) large scale air gap. Based on the CMOS high-speed camera, a discharge test with different operating impulse voltage is carried out by constructing a comprehensive observation platform of rod-plate air gap discharge, and a clear discontinuous leader development process picture is captured. Moreover, the leader current, injection charge and leader channel unit length charge, and their characteristics of the change trend are also obtained. Further analysis based on the experimental results shows that the discontinuous leader development under the action of the impulse voltage with low rate of voltage rising has two different laws. Finally, this paper uses the thermodynamic equation, combined with the test results, the channel temperature changes in the discontinuous leader development stagnation stage were calculated. The results show that the leader channel temperature is still greater than 1500 K in the hundreds of microsecond time scales in the leader stagnation stage, and the subsequent leader can continue to develop on the original leader channel.

Susceptibility of African buffalo and Boran cattle to Trypanosoma congolense transmitted by Glossina morsitans centralis

1990 ◽  
Vol 35 (3) ◽  
pp. 219-231 ◽  
Author(s):  
J.G. Grootenhuis ◽  
R.H. Dwinger ◽  
R.B. Dolan ◽  
S.K. Moloo ◽  
Max Murray
Keyword(s):  
Trypanosoma Congolense ◽  
African Buffalo ◽  
Glossina Morsitans ◽  
Glossina Morsitans Centralis

Active and resting behaviour of virgin and pregnant females ofGlossina morsitans morsitansWestwood (Diptera: Glossinidae) in the laboratory

1982 ◽  
Vol 72 (2) ◽  
pp. 271-288 ◽  
Author(s):  
C. Rowcliffe ◽  
L. H. Finlayson
Keyword(s):  
High Temperature ◽  
Late Pregnancy ◽  
Glossina Morsitans Morsitans ◽  
Glossina Morsitans ◽  
Clear Preference ◽  
Resting Sites ◽  
Pregnant Females ◽  
Resting Behaviour ◽  
Visual Contrast ◽  
Light Gradient

AbstractActivity in virgin and pregnant females ofGlossina morsitans morsitansWestw. was very low and mostly took the form of short bursts of flight. Recently-fed virgins and females in early and mid-pregnancy were least active. In late pregnancy, activity increased and more walking occurred. In all classes of females, activity was least around midday, but the V-shaped curve became less pronounced as parturition approached. There was evidence of a slight preference for black over white surfaces whenlandingbut a clear preference for blackrestingsites. Virgin females preferred to alight and rest on vertical surfaces at the borders of areas of visual contrast; pregnant females preferred to alight and rest on horizontal surfaces and showed no attraction to regions of contrast. In a horizontal light gradient, pregnant females selected lighter resting sites as the day progressed. In late pregnancy, there was an increasing tendency to rest in darker sites. Increasing the temperature in the light gradient caused an increase in activity around 34°C and a switch to photonegative behaviour. After larviposition, the females became strongly photopositive even at high temperature (38°C), but after a feed they reverted to the ‘normal’ photonegative response to high temperature.

scholarly journals Evidence of exposure to SARS-CoV-2 in cats and dogs from households in Italy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
E. I. Patterson ◽  
G. Elia ◽  
A. Grassi ◽  
A. Giordano ◽  
C. Desario ◽  
...  
Keyword(s):  
Risk Factors ◽  
Large Scale ◽  
Companion Animals ◽  
Neutralizing Antibody ◽  
Northern Italy ◽  
Human Infection ◽  
Pet Ownership ◽  
Natural Conditions ◽  
Factors Associated ◽  
Antibody Titers

AbstractSARS-CoV-2 emerged from animals and is now easily transmitted between people. Sporadic detection of natural cases in animals alongside successful experimental infections of pets, such as cats, ferrets and dogs, raises questions about the susceptibility of animals under natural conditions of pet ownership. Here, we report a large-scale study to assess SARS-CoV-2 infection in 919 companion animals living in northern Italy, sampled at a time of frequent human infection. No animals tested PCR positive. However, 3.3% of dogs and 5.8% of cats had measurable SARS-CoV-2 neutralizing antibody titers, with dogs from COVID-19 positive households being significantly more likely to test positive than those from COVID-19 negative households. Understanding risk factors associated with this and their potential to infect other species requires urgent investigation.

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