Short-Term Increases in Aphid Dispersal From Defensive Dropping Do Not Necessarily Affect Long-Term Biological Control by Parasitoids

2019 ◽  
Vol 112 (4) ◽  
pp. 1552-1559
Author(s):  
Michelangelo La-Spina ◽  
Sarah E Jandricic ◽  
Rose Buitenhuis
Keyword(s):  
Biological Control ◽  
High Rate ◽  
Aphidius Ervi ◽  
Large Cage ◽  
Greenhouse Crops ◽  
Ornamental Crops ◽  
Foxglove Aphid ◽  
And Control ◽  
Over Time

Abstract Foxglove aphid (Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae)) is one of the principal aphid pests of greenhouse ornamental crops in North America. Biological control of foxglove aphid mostly relies on the use of Aphidius ervi Haliday (Hymenoptera: Braconidae). However, studies indicate that A. ervi may not be adapted to search for A. solani, and that in response to parasitoid attack aphids can drop and/or disperse, which may aggravate an infestation. Our goal was to further describe the searching behavior of A. ervi in the presence of foxglove aphids, the corresponding defensive behavior of foxglove aphid and the short- and medium-term effects on both pest dispersal and control by A. ervi. Behavioral observations were done on top and bottom leaves infested with foxglove aphid and a high release rate of A. ervi. Parasitoids tended to land on top leaves; however, more aphids were parasitized on bottom leaves, leading to equal numbers of parasitoid attacks in both locations. Most aphids dropped off the plant in the presence of a parasitoid. In large cage experiments, aphids were allowed to distribute naturally and A. ervi was released. The parasitoid still caused a high rate of aphid dropping. However, only a few aphids were able to successfully reach new plants, and most of these mummified over time. Our studies confirm that parasitoid-induced dispersal of foxglove aphid in greenhouse crops does occur, but also suggests this should not necessarily be a barrier to adoption of biological control, as A. ervi controls the aphids over time.

Long-Term Outcomes of Patients with Acromegaly - A Report from the Swedish Pituitary Register

2022 ◽  
Author(s):  
Steinunn Arnardóttir ◽  
Jacob Järås ◽  
Pia Burman ◽  
Katarina Berinder ◽  
Per Dahlqvist ◽  
...  
Keyword(s):  
High Rate ◽  
Hormone Deficiency ◽  
Visual Field Defects ◽  
Mortality Data ◽  
Pituitary Hormone ◽  
Biochemical Control ◽  
Long Term Outcomes ◽  
Over Time

Objective: To describe treatment and long-term outcomes of patients with acromegaly from all health-care regions in Sweden. Design and Methods: Analysis of prospectively reported data from the Swedish Pituitary Register of 698 patients (51% females) with acromegaly diagnosed from 1991-2011. The latest clinical follow-up date was December, 2012, while mortality data were collected for 28.5 years until June, 2019. Results: The annual incidence was 3.7/million; 71% of patients had a macroadenoma, 18% had visual field defects, and 25% had at least one pituitary hormone deficiency. Eighty-two percent had pituitary surgery, 10% radiotherapy and 39% medical treatment. At the 5- and 10-year follow-ups, IGF-I levels were within the reference range in 69% and 78% of patients, respectively. In linear regression the proportion of patients with biochemical control including adjuvant therapy at 10 year follow-up increased over time with 1.23 % per year. The SMR (95% CI) for all patients was 1.29 (1.11-1.49). For patients with biochemical control at the latest follow-up, SMR was not increased, neither among patients diagnosed 1991-2000, SMR 1.06 (0.85-1.33) or 2001-2011, SMR 0.87 (0.61-1.24). In contrast, non- controlled patients at the latest follow up from both decades had elevated SMR, 1.90 (1.33-2.72) and 1.98 (1.24-3.14), respectively. Conclusions: The proportion of patients with biochemical control increased over time. Patients with biochemically controlled acromegaly have normal life expectancy while non-controlled patients still have increased mortality. The high rate of macroadenomas and unchanged age at diagnosis illustrates the need for improvements in the management of patients with acromegaly.

scholarly journals An Evaluation of Dazomet Incorporation Methods on Soilborne Organisms and Pine Seedling Production in Southern Nurseries

2003 ◽  
Vol 27 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Stephen W. Fraedrich ◽  
L. David Dwinell
Keyword(s):  
Morphological Characteristics ◽  
High Rate ◽  
Parasitic Nematodes ◽  
Seedling Production ◽  
Seedling Density ◽  
The North ◽  
Nursery Plant ◽  
Shoot Weight ◽  
And Control

Abstract The use of dazomet as a fall and spring fumigant for pine seedling production and control of soilborne pests was evaluated at two southern nurseries. Dazomet was applied at low (280–325 kg/ha) and high (493–560 kg/ha) rates and incorporated with a rototiller or spading machine. Comparisons were made with methyl bromide/chloropicrin (MBC) fumigation and nonfumigated control treatments. Dazomet incorporation method had no effect on seedling density at either nursery, and often did not affect seedling morphological characteristics. At the Georgia (GA) nursery, seedling density and morphological characteristics did not differ among fumigant treatments except in the spring study area where shoot weight was greater in the MBC treatment than the dazomet or nonfumigated control treatments. In the fall study area at the North Carolina (NC) nursery, seedling density was greater in the high-rate dazomet treatment than the nonfumigated control. Seedlings were generally larger in MBC and dazomet treatments than the control. Seedling density and morphological characteristics did not differ among fumigation treatments in the spring study area. Fumigation with MBC or dazomet generally reduced the percentage of roots withPythium andFusarium spp. compared to controls at the GA nursery and the fall fumigation area in the NC nursery. Plant parasitic nematodes were found infrequently at both nurseries and did not differ among treatments. Nutsedge (Cyperus spp.) was the major problem at the GA nursery and was effectively controlled only with MBC. Compared to the MBC treatment, the abundance of soilborne fungi and the association of certain types ofTrichoderma with roots was often lower in the dazomet treatments. The importance of these differences for long term seedling production and management of soilborne diseases is not known at this time. South. J. Appl. For. 27(1):41–51.

Effect of an acidifying nitrogen fertiliser and lime on soil pH and wheat yields. 1. Soil effects

1994 ◽  
Vol 34 (2) ◽  
pp. 237 ◽  
Author(s):  
MG Mason ◽  
WM Porter ◽  
WJ Cox
Keyword(s):  
Soil Ph ◽  
Ammonium Phosphate ◽  
High Rate ◽  
Continuous Cropping ◽  
Exchangeable Ca ◽  
Acid Accumulation ◽  
Soil Effects ◽  
P Application ◽  
Over Time

Three long-term trials were commenced in 1980 at Merredin, Wongan Hills, and Newdegate to investigate the effect of an acidifying fertiliser containing 17.5% nitrogen (N) and 7.6% phosphorus (P) (based on ammonium sulfate and ammonium phosphate) on soil pH, soil acidity related problems, and wheat grain yields under continuous cropping. Treatments were 3 rates (kg/ha) of N + P applied with the cereal seed (nil; 17.5 N + 7.6 P; 35 N + 15.2 P), with or without 3 t/ha of ground limestone (with or without MgSO4, KCl, Moo3) applied in 1980. Two extra treatments were 2 rates of limestone (70, 140 kg/ha) topdressed with the cereal crop each year along with the low and high N + P fertiliser treatments, respectively. This paper reports soil properties for the first 10 years of the trials. In the acidic Merredin soil (pH 4.3), there was minimal effect of N + P fertiliser on soil pH. The pH was slightly reduced at 0-10 cm depth. At Wongan Hills, soil pH at 0-10 cm depth was reduced over time by N + P application from 4.8 to 4.2. At Newdegate, only the high rate of N + P reduced pH over time, from 4.6 to 4.3 at 0-10 cm. Limestone at 3 t/ha in 1980 increased soil pH at 0-10 cm depth at all 3 sites; however, in all cases pH fell with time. Limestone applied at 70 or 140 kgha with each N + P application increased pH at 0-10 cm depth by 0.1-0.4, 0.1-0.4, and 0.3-0.9 pH units at Merredin, Wongan Hills, and Newdegate. Soil aluminium (Al) concentrations (extracted in 0.01 mol CaCl2/L) were generally low at Wongan Hills and Newdegate in the absence of N + P fertiliser. These levels rose after N + P application to 4 and 2 �g/g at 0-10 cm depth at Wongan Hills and Newdegate. Soil A1 concentrations at Merredin were high, particularly in the subsoil: 3-5, 9-13, and 23-29 �g/g in the 0-10, 10-20, and 20-40 cm depths. With the high rate of N + P, A1 concentration rose to 10 �g/g at 0-10 cm. Application of 3 t/ha of limestone reduced this to <1-2 �g/g. Application of 140 kg/ha of limestone with the high N + P fertiliser rate lowered soil A1 concentration at 0-10 cm. Extra acid that accumulated in treated plots compared with control plots varied from -34.7 kmol/ha (acid-neutralised) for the treatment at Merredin receiving only 3 t lime/ha in 1980 to 23.8 kmol/ha for the treatment at Wongan Hills receiving high N + P. With the treatments receiving lime only, the amounts of acid neutralised were only 82, 66, and 58% of those predicted at Merredin, Wongan Hills, and Newdegate, respectively. Acid accumulation in the 3 treatments receiving high N + P was within the predicted range at Wongan Hills, as it was for the treatment receiving high N + P plus 3 t lime/ha in 1980 at both Merredin and Newdegate. However, for the treatments receiving only high N + P or high N + P plus 140 kg lime/ha. year at these 2 sites, the acid accumulation rates were less than predicted. Levels of exchangeable cations in the soil were highest at Wongan Hills and lowest at Newdegate. Application of N + P decreased Ca concentration at all sites and reduced the concentration of exchangeable Mg at Wongan Hills. Lime applied at 3 t/ha increased the concentrations of exchangeable Ca and Mg at all sites. There were no effects of treatments on concentrations of exchangeable K or sodium.

Dropping behaviour in Aulacorthum solani (Hemiptera: Aphididae) following attack by Aphidus ervi (Hymenoptera: Braconidae): are sticky stem bands a useful integrated pest management method?

2012 ◽  
Vol 144 (4) ◽  
pp. 589-598 ◽  
Author(s):  
David R. Gillespie ◽  
Susanna Acheampong
Keyword(s):  
Biological Control ◽  
Integrated Pest Management ◽  
Pest Management ◽  
Management Strategy ◽  
Aphidius Ervi ◽  
Management Method ◽  
Aulacorthum Solani ◽  
Sticky Tape ◽  
Foxglove Aphid ◽  
Overall Mortality

AbstractWe studied the dropping behaviour of the foxglove aphid, Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae), in response to disturbance by the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae). We banded plant stems with sticky tape to prevent aphids from returning to the plants to determine if these would serve as an integrated pest management strategy for A. solani. Stem banding prevented A. solani that had dropped from returning to the plant; but the mortality associated with banding was not necessarily complementary to biological control by A. ervi. Up to 80% of aphids dropped in response to foraging by A. ervi, and thus could be killed on sticky stem bands. The fraction of aphids that dropped to the ground also contained as much as 90% of the parasitoid's offspring. Overall, mortality of aphids on sticky stem bands was not compatible with parasitoids. Although numbers of aphids declined more rapidly in the first 2 weeks of the trial in the presence of stem bands and parasitoids than in the presence of parasitoids alone, the numbers of aphids were identical in the two treatments from the 3rd week onward. Mortality on the stem bands replaced mortality from parasitoids, and reduced recruitment of parasitoids.

scholarly journals Northern White-Cedar Regeneration Dynamics on the Penobscot Experimental Forest in Maine: 40-Year Results

2010 ◽  
Vol 27 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Catherine Larouche ◽  
Laura S. Kenefic ◽  
Jean-Claude Ruel
Keyword(s):  
Population Densities ◽  
Partial Cutting ◽  
Thuja Occidentalis ◽  
White Cedar ◽  
Sapling Growth ◽  
Northern White Cedar ◽  
And Control ◽  
Over Time ◽  
Measurement Period

Abstract The objective of this study was to assess the long-term dynamics of northern white-cedar (Thuja occidentalis L.) seedling and sapling growth and mortality on the Penobscot Experimental Forest in Maine. Data collected between 1965 and 2005 in four twice-replicated partial cutting treatments were analyzed. White-cedar seedlings established in all treatments despite relatively high white tailed-deer (Odocoileus virginianus Zimmerman) population densities. However, although it appears that regeneration cohorts of associated softwoods increased in size over time, the white-cedar cohort did not. Ingrowth of white-cedar from the seedling to sapling stage was lower than the combined rates of sapling mortality and recruitment to the pole stage; sapling density of this species in 2005 was >80% less than it was at the start of the measurement period. Sapling mortality was high, and recruitment to larger size classes was low, although mortality decreased and recruitment increased as sapling size increased. Browsing was prolific; 90% of white-cedar seedlings and small saplings showed signs of browse in 2005. Overall, white-cedar sapling growth was slow, with an estimated 100 years needed to grow from small sapling to merchantable size in the study stands. Efforts to release white-cedar saplings through precommercial treatment and control of browsing pressure are recommended.

Trends in the legal status of indigenous species

2000 ◽  
Vol 27 (4) ◽  
pp. 404-413 ◽  
Author(s):  
E. Knegtering ◽  
H.J. van der Windt ◽  
A.J.M. Schoot Uiterkamp
Keyword(s):  
Legal Status ◽  
Indigenous Species ◽  
Species Relationships ◽  
Human Species ◽  
Species Characteristics ◽  
Species Specific ◽  
And Control ◽  
Over Time ◽  
Ethical Perspectives

Which species will be intentionally preserved depends on societal perspectives regarding nature and species, but these have been little studied. In this study, it was hypothesized that in species-specific conservation, aesthetical perspectives, notably the appreciation of species characteristics as embodied in taxa, are important. However, this importance is changing due to variation in ecological (in particular, knowledge of species’ populations) and ethical perspectives (in particular regarding specific human-species relationships). The hypothesis was approached by assessing the relative involvement of different taxa in species-specific legislation on wild animals in the Netherlands over the period 1857–1995. Three objectives in this legislation were defined namely, ‘control’, ‘use’ and ‘protection’, based on purposes and potential levels of legally allowable taking. Over time, the number of species protected increased, whereas the numbers subject to ‘use’ and ‘control’ reached a peak and decreased again. The taxa included birds, mammals, amphibians, reptiles, fishes, bivalves, gastropods, cephalopods, insects, crustaceans and asteroids. Persistent differences were found in the relative involvement of taxa in the objectives as well as in the relative extent to which taxa were affected by long-term trends in numbers of species subject to the objectives. The results also show that species of one-and-the-same taxon were not regarded equally over time. It is concluded that the long-term changes in species’ legal status probably resulted from the combined effects of both the appreciation of species characteristics embodied in taxa and, in particular, changes in ethical perspectives regarding human-species relationships.

scholarly journals Mechanisms of non-consumptive effects of parasitoid wasps on aphid populations : enhancing aphid suppression by increasing natural enemy and plant diversity

2016 ◽  
Author(s):  
◽  
Kathryn Suzanne Ingerslew
Keyword(s):  
Biological Control ◽  
Plant Diversity ◽  
Natural Enemies ◽  
Pea Aphid ◽  
Aphidius Ervi ◽  
Pest Species ◽  
Short Term ◽  
Pea Aphids ◽  
Aphid Populations

Predators are typically evaluated for their potential effectiveness as natural biological control agents by examining traits related to their consumptive relationship with an herbivore. For example, voracious predators with a high prey attack rate or predators that specialize in consuming a particular pest species are considered ideal for biological control. However, there is a growing body of research demonstrating that predators also influence herbivore population size through non-consumptive interactions. Non-consumptive interactions include changes in prey behavior, morphology, or life-history traits in response to the presence of a predator that allow prey to survive a predator encounter but result in declines in prey fitness due to reduced availability of resources or expending energy that would have been otherwise used for growth or reproduction. The existence of non-consumptive effects is significant because it raises the possibility that a non-lethal organism (i.e. non-enemy) in the environment can also contribute to herbivore suppression if an herbivore inaccurately perceives an organism as a threat and engages in a defensive response. The goal of my dissertation research was to determine whether non-enemies contribute to natural biological control and enhance herbivore suppression beyond levels accomplished by consumptive natural enemies alone. Previous work in our lab demonstrated that pea aphids Acyrthosiphon pisum (Harris) respond to the non-enemy wasp Aphidius colemani Viereck by stopping feeding and dropping off of their host plant, resulting in a decline in pea aphid abundance even though pea aphids are not a host for A. colemani. My work evaluated whether this behavioral suppression of pea aphid populations by the non-enemy wasp is complementary with pea aphid suppression by the consumptive enemy Aphidius ervi Haliday. I investigated 1) the mechanisms responsible for and the magnitude of the non-consumptive effects of A. colemani and A. ervi on pea aphid populations, 2) the contributions of non-consumptive interactions to short-term and long-term suppression of aphid populations in the presence of consumptive natural enemies, and 3) the feasibility of increasing plant diversity in the field to enhance pea aphid suppression by facilitating behavioral non-consumptive interactions. I found that pea aphids respond to interactions with both wasp species, but they more frequently engaged in defensive behaviors such as dropping in the presence of the enemy A. ervi than the non-enemy A. colemani. The behavioral response of the pea aphid to the presence of the non-enemy was strong enough for A. colemani to suppress pea aphid populations in the short term, but this suppression was not maintained over the long term. When the non-enemy A. colemani was combined with the consumptive enemy A. ervi, there was some evidence for antagonism between the wasps over the short term. However, the non-enemy and enemy were complementary in their suppression of pea aphid populations over the long term, with more consistent and stable suppression when both wasps were present. I also demonstrated that increasing plant diversity in a field setting enhances suppression of pea aphid populations by promoting interactions between pea aphids and non-enemies. My work demonstrates that non-lethal organisms, or non-enemies, in the environment have an important role to play in influencing herbivore abundance, and that the addition of non-enemies to a community of lethal predators and parasitoids can lead to greater and more consistent suppression of herbivores in the long term.

scholarly journals Capital structure in blockholder-dominated firms: a closer look on corporate ownership and control

2010 ◽  
Vol 7 (3) ◽  
pp. 86-104
Author(s):  
Ottorino Morresi
Keyword(s):  
Capital Structure ◽  
Family Firms ◽  
Corporate Ownership ◽  
Founding Family ◽  
Italian Context ◽  
Cash Flow Rights ◽  
And Control ◽  
Pyramidal Groups ◽  
Over Time

In countries where holding control takes on much relevance it is arguable that capital structure choices are shaped in response to ownership characteristics. These issues are explored in the Italian context being dominated by pyramidal groups and majority-controlled firms. The results show that (1) family firms are more indebted than non-family counterparts and, within family firms, (2) founding-family controlled ones are more reliant on debt; (3) family firms exploit control-enhancing devices along with long-term leverage; (4) higher cash flow rights are associated with a lower leverage; (5) institutional investors are more common in firms with a higher dependence on long-term debt; (6) decreasing trends of the long-term leverage over time seem to occur with upward paths of the votes-to-capital ratio

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

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