Field evaluation of the suitability of four Brassica and two Sinapis species (Brassicaceae) as host plants of Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae)

1996 ◽  
Vol 76 (1) ◽  
pp. 203-205 ◽  
Author(s):  
G. H. Gerber

The relative suitability of Sinapis alba L., Sinapis arvensis L., Brassica carinata A. Braun, Brassica juncea (L.) Czern, Brassica napus L., and Brassica rapa L. as host plants for Lygus lineolaris (Palisot de Beauvois) was measured by comparing the numbers of colonizing adults (first generation), nymphs (second generation), and new-generation adults (second generation) on these species in field plots during flowering and seed development in July and August 1994. The mean numbers of first-generation adults and second-generation nymphs were not significantly different on the six species of Brassica and Sinapis. The mean number of second-generation adults differed significantly on these species, but the differences were relatively small. The results indicate that the six species of Brassica and Sinapis tested are suitable host plants of L. lineolaris and have similar levels of suitability. Key words: Insecta, Miridae, Lygus lineolaris, host plants, Brassica, Sinapis

1995 ◽  
Vol 127 (4) ◽  
pp. 543-559 ◽  
Author(s):  
G.H. Gerber ◽  
I.L. Wise

AbstractThe seasonal occurrence and number of generations of Lygus lineolaris (Palisot de Beauvois) were studied on alfalfa (Medicago sativa L.), everbearing strawberries (Fragaria × ananassa Duchesne), oilseed rape (Brassica napus L.), and stinkweed (Thlaspi arvense L.) in field plots at Winnipeg, Manitoba, and in commercial alfalfa and oilseed rape fields throughout the agricultural areas of Manitoba in 1990–1993. Lygus borealis (Kelton) was studied only during 1993. Lygus lineolaris had two non-overlapping generations in southern Manitoba. Overwintered adults migrated onto host plants during die first 3 weeks of May, and females containing chorionated eggs were found in relatively small numbers for 5–6 weeks until the last 3 weeks of June. First-generation nymphs were present from the last half of May until the last half of July. During the last 2 weeks of June, the overwintered adults disappeared suddenly and were replaced completely by first-generation adults. First-generation adults eclosed during the last 2 weeks of June and in July, and first-generation females containing chorionated eggs were present for about 6–7 weeks until mid-August. Second-generation nymphs first appeared in late July or early August and most completed development by the end of September. Second-generation adults were found from the first half of August until they hibernated in October and November. Most second-generation females contained previtellogenic eggs and. therefore, were in reproductive diapause. In 3 of the 4 years, the overwintered adults appeared to include all second-generation adults plus 0–20% of the first-generation adults. The data from commercial alfalfa and oilseed rape fields indicated that the seasonal occurrence of L. lineolaris was relatively uniform in most or all agricultural areas of Manitoba. Lygus lineolaris has one generation (the second generation) on oilseed rape, and the eclosion and dispersal of reproductively active first-generation adults were well synchronized with the bud and flower stages of this host plant in southern Manitoba. In 1993, L. borealis had two generations and its seasonal occurrence was similar to that of L. lineolaris.


1997 ◽  
Vol 129 (4) ◽  
pp. 777-787 ◽  
Author(s):  
J.H.M. Leferink ◽  
G.H. Gerber

AbstractThe development of adult and nymphal populations of Lygus lineolaris (Palisot de Beauvois), L. elisus Van Duzee, and L. borealis (Kelton) was studied in relation to seeding date and stage of plant development in four seedings of canola (cv. Westar) in field plots at Glenlea, Manitoba, in 1988 and 1989. Lygus lineolaris was the dominant species in all seedings and in both years. Colonizing adults (first-generation adults) of the three Lygus spp. first invaded the plots at about the same time from the late rosette to the early flowering stages of plant development, and Lygus adult numbers reached maxima during flowering in all seedings. The stage of plant development, and not seeding date, was important in attracting colonizing adults of Lygus to canola. Second-generation nymphs first appeared at the flowering stage of canola. All nymphal instars reached maxima and median abundances during the late flowering and pod development stages in all seedings. Second-generation adults were present from early to late pod development stages. Median abundances of second-generation adults of L. lineolaris, L. elisus, and L. borealis usually were reached at the same plant growth stage in each seeding.


1993 ◽  
Vol 28 (2) ◽  
pp. 218-229
Author(s):  
Mark A. Coffelt ◽  
Peter B. Schultz

Population biology of orangestriped oakworm, Anisota senatoria (J. E. Smith), was studied in southeastern Virginia. Egg mass size was larger on Quercus palustris Muench., pin oak, compared with Q. phellos L., willow oak. Females produced a sex pheromone that attracted male moths. Blacklight traps were not effective for monitoring A. senatoria adults. Peak male emergence occurred on 2 July, 4 days earlier than female. The mean life span was 33.5 days in the laboratory. Pupal mortality was high and only 1.2% of the pupae produced moths in 1989 and 1990. Pupae were capable of overwintering for two years in the field. The first report of a second generation from September - November was documented. Second generation A. senatoria oviposited more egg masses, infested more trees and had a longer development time compared with first generation. Large egg mass size, pupae that were capable of overwintering for two years and the presence of a second generation may partially explain the consistent A. senatoria populations that have occurred in southeastern Virginia.


1963 ◽  
Vol 95 (2) ◽  
pp. 113-126 ◽  
Author(s):  
N. D. Holmes ◽  
W. A. Nelson ◽  
L. K. Peterson ◽  
C. W. Farstad

AbstractAdults of B. cephi emerged at the same time as the adults of their host, the wheat stem sawfly, and started to oviposit about mid-July. The second generation started to emerge between August 5 and 15. This generation, which was complete in some years, was apparently only partial in years in which adults of the first generation continued to oviposit late in the season. In most cases the larvae of Bracon that were present at harvest time were from eggs laid after August 1.Most of the overwintering B. cephi were located in the lower internodes of the sawfly-infested wheat stems. Although B. cephi attacked some sawfly larvae in their stubs most sawflies escaped parasitism once they had cut their host stems.High host densities per stem in hollow-stemmed wheats were detrimental to Bracon during the early part of the season as the unparasitized sawfly larvae in stems containing B. cephi destroyed the parasite larvae.The sawfly-susceptible wheats were more suitable than the resistant for parasitism. Generally, differences in parasitism between wheats and between barleys were caused by differences in length of survival of the sawfly larvae in the different host plants; longer survival led to higher parasitism.The fluctuations in amounts of parasitism mainly depended on the synchronization of development between B. cephi and the sawfly. Parasitism increased when the sawfly larvae cut their host stems sufficiently late to allow establishment by the second generation of B. cephi and decreased when the sawfly cut too early for parasitism by the second generation. The date of ripening of the host plant governs the date of cutting by the sawfly; hence, the amount of parasitism is influenced by the levels of soil moisture and temperature during the growing season, by differences in rate of development of various plant hosts, and by the date of seeding. Low levels of parasitism resulted from early ripening of the sawfly host plants in two consecutive years, whereas a moderately high level occurred even though the weather of the current year was conducive to early ripening, provided that the wheat in the preceding year had ripened late. It appears that moderate to high levels of parasitism required that the crop ripen late in at least one year out of two.


1990 ◽  
Vol 3 (4) ◽  
pp. 252-261
Author(s):  
Candace S. Brown ◽  
Stephen G. Bryant

The major advantage of the new generation of antidepressants lies in their enhanced ability to avoid unwanted side effects, such as anticholinergic or cardiovascular toxicities, and in many cases, to reduce fatalities after overdose. Second-generation antidepressants are as effective as the first generation agents, but are more selective, enabling precise targeting of symptoms. Caution in recommending the newer antidepressants must be applied, however, because these agents possess differing side effects, and unforeseen toxicities may not appear until after several years of use. Conventional tricyclics should not be overlooked in managing the depressed patient. This article discusses the symptoms of major depression, followed by the latest information on second-generation antidepressants. It concludes by providing the pharmacist with guidelines for when to select a newer over an older agent.


Author(s):  
NATALIA V. VARLAMOVA

The digitalization substantially affects virtually all social relationships, the fact that requires reassessment of many basic legal concepts. Among them are human rights. It is now increasingly asserted that technological innovations result in the emergence of new digital rights being that fundamentally differ from conventional rights and form a new generation of human rights. The most frequent among such rights are a right to internet access, right to personal data protection and right to be forgotten (right to erasure). To assess the validity of such assertions it is necessary to clarify the grounds for classification of human rights by generations and to determine the correlation between new human rights and the conventional ones.The classification of human rights by their generations offered in 1970 by K. Vasak can be based upon substantive (essential) and chronological criteria. In the latter case the number of new generations of human rights can be whatsoever high while the difference between them is insignificant. If to proceed from the substantive criterion, the rights of the first generation express claims of a human being towards individual freedom and assume the obligation of the State to respect and protect it; rights of the second generation are claims towards social assistance on the part of the State and society to maintain an adequate standard of living; rights of the third generation are a sort of projection of rights of the first and second generations to relations between social communities (international, in proper sense, non сross-border, relations). In such context to substantiate the emergence of a new generation of human rights it is necessary to prove that the related rights forming it have an absolutely different legal nature as compared to the rights of the first and second generations.The right for internet access in international acts, national constitutions and laws as well as in judicial practice is primarily treated as a condition and guarantee of exercise of conventional human rights. Along with this, with due regard to a special significance of Internet for exercise of many human rights, development of democracy and civil society, transparency of state administration the access to it may be recognized as an independent human right. However, the legal nature of such right is quite conventional, it includes claims related both to the first and second generation of human rights. As a right of the first generation it assumes negative obligations of the State not to prohibit and not to restrict an access to Internet (certain Internet resources) and its positive obligations to establish a statutory regulation of access to Internet and provision of protection against illegal restrictions, interalia, on the part of private entities. As a right of the second generation the accessibility of Internet in its material and technical aspects may be regarded, the fact that assumes positive obligations of the State to establish a corresponding infrastructure, to subsidize the provider-supplied services, to organize public access points and to develop educational programs etc. Moreover, the currently applicable international and national regulation of this sphere of relations does not allow asserting that the legal recognition of the right to Internet access has taken place.


1992 ◽  
Vol 66 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Rakotondravao ◽  
A. Moukrim ◽  
P. Hourdin ◽  
D. Rondelaud

ABSTRACTLymnaea truncatula, 4 mm in height, were subjected to infection by a single miracidium of Fasciola gigantica, then raised at 23°C until day 60 of the experiment. Histological study of these snails demonstrated a mean redial burden of 34 parasites at day 60, of which one third were degenerating forms. The mean number of living independent rediae did not exceed 5 for the first and second generations. Conversely, in subsequent generations there were as many as 18 rediae per snail at day 60. The first living redia of the first generation in particular gave rise to daughter rediae. Mature rediae appeared at day 35 and especially concerned the first and second generations at day 60. The authors conclude that development of the first and second redial generations occurs during the same period, and that the forms of the first cohort of the second generation are produced from the first redia of the first generation which originated from the sporocyst.


Author(s):  
S. Lee ◽  
W. Sutomo ◽  
C. Liu ◽  
E. Loth

This study investigated the development of microbubble injection using a MEMS-based electrolytic device capable of generating small bubbles introduced with nearly zero injection velocity. Three generations of electrolytic microbubblers with gold electrodes and photoresist (PR) as an insulator were fabricated. The objective for the first-generation microbubbler was to understand the influence of voltage and flow speed. The goal of the second-generation microbubbler was to understand the influence of electrode area and spacing, the distance between the cathode and anode. The purpose of the third generation device was to investigate the effect of electrode shape as well as further reduction in the size and spacing of the electrodes. Measurements of the sizes of the bubbles and the bubble generation rates of a first-generation device in a square water channel at different voltages and under different flow conditions were taken. At all but the lowest applied voltage, more than 65% of the observed bubbles were less than 50 μm in diameter. As the applied voltage was increased, the mean bubble diameter and the variation from the mean decreased while bubble generation rates increased. As the flow increased, mean bubble diameter and the deviation from the mean decreased as well. For the second-generation devices, the largest mean bubble diameter and smallest percentage of bubbles smaller than 50 μm occurred at an intermediate value of the ratio between the electrode size and the electrode spacing of approximately 0.7. For the third generation devices, increased detachment frequency occurred with the circular geometries, compared to triangular or square node shapes. The minimum allowable spacing between two electrodes to avoid coalescence was approximately 1.5 times the electrode diameter.


1992 ◽  
Vol 82 (3) ◽  
pp. 299-306 ◽  
Author(s):  
A. Blackwell ◽  
A.J. Mordue (Luntz) ◽  
M.R. Young ◽  
W. Mordue

AbstractStudies on Culicoides spp. biting midges in south-west Scotland in 1991 revealed that Culicoides impunctatus Goetghebuer, the dominant species throughout the season (May-September), was bivoltine, with a generation period of six weeks. Unseasonal climatic conditions during much of June resulted in a low proportion of first generation females surviving to the parous stage and a reduction in the overall, expected size of the second generation. Distinct behavioural phases of the female midges, such as resting, dispersal and host-seeking, were shown to be directly related to parity states (determined by fat body condition and ovarian development) during the gonotrophic cycle. Female flight activity increased after laying the first, autogenous egg batch, whereas males never flew far from the emergence site. The mean parous rate formula was used to calculate the survival rate of second generation nulliparous females, which was 0.57 per gonotrophic cycle.


Sign in / Sign up

Export Citation Format

Share Document