NATURAL CONTROL OF HEMLOCK SAWFLY, NEODIPRION TSUGAE (HYMENOPTERA: DIPRIONIDAE), POPULATIONS IN SOUTHEAST ALASKA

1976 ◽  
Vol 108 (5) ◽  
pp. 485-498 ◽  
Author(s):  
John S. Hard
Keyword(s):  
Food Quality ◽  
Low Temperatures ◽  
Population Trends ◽  
Biotic Factors ◽  
Natural Control ◽  
Parasitoid Species ◽  
Southeast Alaska ◽  
Heat Units ◽  
Large Numbers ◽  
Southern Half

AbstractHemlock sawfly infestations occur most commonly in the warm southern half of southeast Alaska. Biotic factors that limit sawfly populations are a fungus, Entomophthora sphaerosperma, which kills disproportionately large numbers of female larvae; food quality as affected by host site and defoliation; and three ichneumonid parasitoid species, Delomerista japonica diprionis, Oresbius tsugae tsugae, and Itoplectis quadricingulatus, which attack prepupal larvae in cocoons. E. sphaerosperma was the most effective natural control in recent years, especially during wetter than normal summers. Parasites which attack after the fungus has decimated larval populations were most abundant during two dry summers. Parasitization and sawfly emergence were directly related, and both were highly inversely correlated with percentage fungus killed sawflies. Sawflies reared on lightly defoliated trees produced significantly more eggs than those reared on heavily defoliated trees, and fecundity was directly related to cumulative heat units during the summer. Between 1952 and 1974, most negative sawfly population trends south of Frederick Sound occurred when two wet summers occurred consecutively. Apparent widespread collapse of sawfly populations in 1974 was associated with low temperatures in 1973 which delayed sawfly development and reduced opportunities for successful oviposition.

Diving beetles (Dytiscidae) as predators of mosquito larvae (Culicidae) in field experiments and in laboratory tests of prey preference

2003 ◽  
Vol 93 (3) ◽  
pp. 219-226 ◽  
Author(s):  
E. Lundkvist ◽  
J. Landin ◽  
M. Jackson ◽  
C. Svensson
Keyword(s):  
Body Length ◽  
Negative Correlation ◽  
Laboratory Tests ◽  
Field Experiments ◽  
Mosquito Larvae ◽  
Natural Control ◽  
Large Numbers ◽  
Diving Beetles ◽  
The Mean ◽  
Artificial Ponds

AbstractField experiments were performed in artificial ponds to evaluate how the density of predatory diving beetles (Dytiscidae) would affect the population levels of mosquito larvae (Culicidae). Mosquitoes colonizing the ponds were predominantly species of the genus Culex. In 2000, most of the dytiscids colonizing the ponds were small (Hydroporus spp.), and these predators had no impact on the size of larval mosquito populations, not even in ponds with added dytiscids. In 2001, larger beetles (Ilybius, Rhantus, and Agabus spp.) were more common, and there were significantly fewer mosquito larvae in ponds with the highest numbers of dytiscids. There was a negative correlation between numbers of diving beetles in the ponds and the mean body length of mosquito larvae. In neither year could dytiscid densities be maintained above a certain level owing to emigration. In laboratory tests, there were marked differences between three common dytiscid species in regard to preferences for Daphnia and Culex species as prey: Colymbetes paykulli Erichson chose mosquito larvae more often, whereas both Ilybius ater (De Geer) and I. fuliginosus (Fabricius) preferred Daphnia spp. All of the tested dytiscids consumed large numbers of prey. Since some dytiscid species can efficiently decrease populations of mosquito larvae, they are probably important in the natural control of these dipterans.

Mineralogy and cryptic layering of the Kunene anorthosite complex of SW Angola and Namibia

1992 ◽  
Vol 56 (384) ◽  
pp. 319-327 ◽  
Author(s):  
Zenaide C. G. Silva
Keyword(s):  
Low Temperatures ◽  
Gabbroic Rock ◽  
Rock Types ◽  
Northern Half ◽  
Western Area ◽  
Southern Half ◽  
Mineral Compositions ◽  
Anorthosite Complex

AbstractThe gabbro-anorthosite complex of SW Angola and Namibia (Kunene Complex) is dominated by anorthosite-troctolite cumulates. Other broadly gabbroic rock types are subordinate. An-rich plagioclase (max. An85) and Fo-rich olivine (max. Fo79) are common in the western area of the complex with plagioclase becoming gradually less anorthitic (min. An45) and olivine less forsteritic (min. Fo62) toward the east. This cryptic change is more pronounced in the northern half of the complex where rocks are darker, fresh, and the rhythmic layering is also more conspicuous. Within the white 'massive' anorthosite type, which is largely restricted to the southern half of the intrusion, cryptic layering is less pronounced. Textures indicate that rocks cooled very slowly and the co-existing mineral compositions indicate re-equilibration to usually low temperatures.

scholarly journals Can hyena behaviour provide information on population trends of sympatric carnivores?

2019 ◽  
Vol 374 (1781) ◽  
pp. 20180052 ◽  
Author(s):  
David S. Green ◽  
Matthew T. Farr ◽  
Kay E. Holekamp ◽  
Eli D. Strauss ◽  
Elise F. Zipkin
Keyword(s):  
Wildlife Conservation ◽  
Population Trends ◽  
Future Research ◽  
Spotted Hyena ◽  
Carnivore Species ◽  
Large Numbers ◽  
Disturbed Areas ◽  
Competitive Release ◽  
Conservation Actions ◽  
Sympatric Carnivores

Mammalian carnivores are declining worldwide owing to human activities. Behavioural indicators have the potential to help identify population trends and inform conservation actions, although this area of research is understudied. We investigate whether behaviour is linked to abundance in a community of carnivores in the Masai Mara National Reserve, Kenya. Anthropogenic disturbance increased exponentially in parts of the Reserve between 1988 and 2017, mainly owing to daily incursions by large numbers of livestock and tourists. Previous research showed that hyena behaviour changed markedly during this period. Through a series of vignettes, we inquire whether hyena behaviours correlate with changes in abundance of hyenas themselves, or those of other carnivore species in the region. We find that changes in spotted hyena behaviour in disturbed areas, but not in undisturbed areas, can be linked to changes in their demography (vignette 1). We also find that declines in observed lion–hyena interactions, as well as increases in spotted hyena abundance, are probably caused by competitive release of hyenas from declining lion abundance (vignette 2). Finally, we demonstrate that in some cases, hyena behaviour and demography is linked to the density and distribution of sympatric carnivores, and that behavioural changes in hyenas can provide information on shifts within the carnivore community (vignettes 3 and 4). Our vignettes reveal intriguing relationships between behaviour and demography that should be explored in future research. Pairing behavioural studies with more traditional monitoring efforts can yield useful insights regarding population and community trends, and aid wildlife conservation and management. This article is part of the theme issue ‘Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

CHRYSOPIDS AS A FACTOR IN THE NATURAL CONTROL OF THE ORIENTAL FRUIT MOTH

1932 ◽  
Vol 64 (6) ◽  
pp. 121-126 ◽  
Author(s):  
Wm. L. Putman
Keyword(s):  
Oriental Fruit Moth ◽  
Natural Control ◽  
Large Numbers

During the summer of 1930 it was observed that large numbers of eggs of the Oriental fruit moth (Laspeyresia molesta Busck.) were being destroyed by some enemy which pierced the shell and sucked out the contents. The presence of many chrysopid larvae on the trees indicated that these might be responsible for the destruction of the eggs.

scholarly journals TINGKAT PARASITASI PARASITOID TELUR PBPK PADA PERTANAMAN PADI DENGAN BEBERAPA KETINGGIAN TEMPAT BERBEDA

2016 ◽  
Vol 25 (1) ◽  
pp. 99
Author(s):  
Ni Made Delly Resiani ◽  
I Wayan Sunanjaya
Keyword(s):  
Sea Level ◽  
Stem Borer ◽  
Control Agent ◽  
Yield Losses ◽  
Biological Control Agents ◽  
Natural Control ◽  
Parasitoid Species ◽  
Pests And Diseases ◽  
Plant Pests ◽  
Rice Stem Borer

Rice is the staple food of Indonesia's population. Various problems occur in an effort to increase production and productivity. One problem is the attack of yellow rice stem borer (PBPK) which may result in yield losses up to 90%. Utilization of parasitoid is an alternative to suppress the attack of Yellow Rice Stem Borer. The study was conducted in Tabanan, covering three locations with the altitudes of 50, 300, and 550 meters above sea leve, and at the Plant Pests and Diseases laboratory of the Faculty of Agriculture, University of Udayana. The study aimed to determine the effectiveness of parasitization of the best Yellow Rice Stem Borer as a natural control agent at different altitudes. The method used was survey by taking a sample group of Yellow Rice Stem Borer eggs with a purposive random sampling in the area of 2.5 hectares (one block in each location was an area of 0.5 hectares) at each location. Observations on parasitoid found in Yellow Rice Stem Borer eggs were done on parasitoid species diversity, equality, abundance, parasitation level, sex ratio, and the pattern of parasitoid invasion. The results showed three species of parasitoid eggs PBPK as biological control agents. Parasitation level of T. rowani and T. japonicum was the highest at the altitude of 50 meters above sea level, while T. schoenobii at the altitude of 300 and 500 meters above sea level.

scholarly journals Biological quality of Tetrastichus howardi (Hym.: Eulophidae) reared with Tenebrio molitor (Col.: Tenebrionidae) pupae after storage at low temperatures for different periods

2018 ◽  
Author(s):  
Elison Floriano Tiago ◽  
Fabrício Fagundes Pereira ◽  
Samir Oliveira Kassab ◽  
Rogério Hidalgo Barbosa ◽  
Carlos R Garcia Cardoso ◽  
...  
Keyword(s):  
Biological Control ◽  
Low Temperatures ◽  
Tenebrio Molitor ◽  
Biological Pest Control ◽  
Control Programs ◽  
Low Temperature Storage ◽  
Large Numbers ◽  
Emergence Percentage ◽  
Temperature Storage

Introduction: The endoparasitoid Tetrastichus howardi (Olliff, 1893) (Hymenoptera: Eulophidae) can be reared with the alternative host Tenebrio molitor (Linnaeus, 1758) (Coleoptera: Tenebrionidae). Host storage at low temperatures can regulate parasitoid production and demand in biological control programs. Material and Methods: The life-cycle (egg-adult), parasitism and emergence percentage, number of parasitoids emerged per host pupae, sex ratio and longevity of the T. howardi offspring per T. molitor pupa were evaluated after low temperature storage of this host for different periods and its immature (pupae) in T. molitor pupae for five periods at 10.3 ºC. Tenebrio molitor pupae stored at 0.5 ± 0.09 °C and 2.7 ± 0.11 °C for 10 and 20 days, respectively, were adequate to produce T. howardi. Results: The biological characteristics of this parasitoid were better with T. molitor pupae stored at 0.5 ± 0.09 °C and 2.7 ± 0.11 °C for 10 and 20 days. Tetrastichus howardi immature (pupae) can be stored in T. molitor pupae for 10, 20, 30, 60 and 90 days at 10.3 ºC, preferably in pupae of this host for 10 days to produce these adults of this parasitoid for biological control programs. Discussion: These results contribute to overcoming one of the difficulties encountered in the massive production of parasitoids which is to obtain large numbers of suitable hosts when they are needed. Therefore, the possibility of conserving T. molitor pupae to rear T. howardi will be useful to use this natural enemy in biological pest control programs. Keywords: Biological control, Cold storage, Parasitoids, Progeny.

Herons, Egrets and Bitterns

2005 ◽  
Author(s):  
Neil McKilligan
Keyword(s):  
At Risk ◽  
Population Dynamics ◽  
Present Status ◽  
Breeding Population ◽  
Northern Australia ◽  
Australian Species ◽  
Large Numbers ◽  
The Family ◽  
Southern Half

This is the first book to deal exclusively with the Australian members of the Family Ardeidae (herons, egrets and bitterns). It gives a comprehensive, easy-to-read account of their origins, classification and biology, and explains the features that distinguish them from other birds. The book devotes a major chapter to the 14 Australian species, covering their distribution and movements, feeding, breeding, population dynamics and conservation. Some of Australia’s herons have become very scarce in the southern half of the continent and are at risk of national or local extinction. In northern Australia heron habitats and resources are largely pristine and consequently this region accommodates large numbers of certain species. A final chapter on population and conservation provides a useful summary of the present status of the Australian herons, some of whom are thriving and others who are in a very precarious position.

scholarly journals A recurring salmonellosis epidemic in New Zealand linked to contact with sheep

2006 ◽  
Vol 135 (1) ◽  
pp. 76-83 ◽  
Author(s):  
M. G. BAKER ◽  
C. N. THORNLEY ◽  
L. D. LOPEZ ◽  
N. K. GARRETT ◽  
C. M. NICOL
Keyword(s):  
New Zealand ◽  
Management Practices ◽  
Case Control Study ◽  
Laboratory Data ◽  
Case Control ◽  
Large Numbers ◽  
Southern Half ◽  
Human Infections ◽  
Occupational Contact ◽  
Control Study

One strain of Salmonella Brandenburg began causing large numbers of human infections in New Zealand in 1998. We investigated the emergence of this strain using combined notification and laboratory data on human and animal disease and a case-control study. S. Brandenburg infection in humans was characterized by spring peaks and high rates in the southern half of the South Island. This epidemic pattern followed very closely that seen in sheep. The case-control study found that infection was significantly associated with occupational contact with sheep and having a household member who had occupational contact with sheep, during the 3 days prior to illness or interview. We conclude that S. Brandenburg has become established as a zoonotic disease in New Zealand. Preventing infection requires control of the epidemic in sheep through vaccination, changes in farm management practices, and promotion of hand washing and other precautions to protect farmers and their families.

Studies of Predators of the Balsam Woolly Aphid Adelges piceae (Ratz.) (Homoptera: Adelgidae): IX. Pullus impexus (Muls.) (Coleoptera: Coccinellidae), An Introduced Predator in Eastern Canada,

1961 ◽  
Vol 93 (12) ◽  
pp. 1162-1168 ◽  
Author(s):  
R. C. Clark ◽  
N. R. Brown
Keyword(s):  
Control Program ◽  
Natural Control ◽  
Eastern Canada ◽  
Control Value ◽  
Large Numbers ◽  
Woolly Aphid ◽  
Adelges Piceae ◽  
Available Information ◽  
And Control ◽  
Lower Population

Pullus impexus (Muls.) is one of many species of predators that have been introduced into Eastern Canada since 1933 as part of a biological control program against the balsam woolly aphid, Adelges piceae (Ratz.) Delucchi (1954) has published many details of the systematics, biology, and natural control of this species in Europe where he found it to be associated with all A. piceae infestations. According to Pschorn-Walcher and Zwölfer (1960), it is one of a group of predators that are usually associated with lower population densities of A. piceae and other related adelgids, rhan are Aphidoletes thompsoni Möhn and Laricobius erichsonii Rosen. Because it is common on adelgid infestations in Europe and because it can easily be reared en masse, large numbers have been released in North America. The purpose of the present paper is to bring together available information on releases, life-history and natural control, and control value of this species, obtained from studies carried out over the past nine years in New Brunswick.

Plutella maculipennis, Curt., its natural and biological Control in England

1938 ◽  
Vol 29 (4) ◽  
pp. 343-372 ◽  
Author(s):  
J. Eliot Hardy
Keyword(s):  
New Zealand ◽  
Adult Stage ◽  
High Humidity ◽  
Natural Control ◽  
Moth Population ◽  
Large Numbers ◽  
The World ◽  
High Level ◽  
High Degree ◽  
Eventual Control

1. Plutella maculipennis, Curt., a widespread Lepidopterous pest of Brassica was introduced into New Zealand about sixty years ago. In most countries a high degree of natural control is maintained, but in New Zealand the moth population is permanently maintained at a high level. Investigation showed that in New Zealand there were no natural enemies of importance, while in other areas these are constantly associated with Plutella.2. The distribution of the moth throughout the world is exceedingly wide, but in England it only occasionally reaches pest proportions.3. Preliminary work indicated that two Campoplegines, Angitia cerophaga and A. fenestralis, constantly parasitized large numbers of the Plutella larvae. Initial efforts were devoted to collecting and breeding a large supply of these in England for introduction into New Zealand as controlling agents.4. From several thousand specimens of Plutella, fourteen species of parasites were recovered, of which eight were hyperparasites. The only parasites which were numerically important were the two parasites, Angitia cerophaga and A. fenestralis. Their efficiency is not impaired to any appreciable extent by hyperparasites. A key showing the diagnostic differences of the parasites and hyperparasites of Plutella is given.5. These two species of Angitia are commonly recorded as parasites of Plutella throughout the world, although under different names. A large quantity was bred in the laboratory and despatched to New Zealand after overcoming certain difficulties connected with transport. It appears that both species of parasite must overwinter in other hosts than Plutella.6. Certain experiments were performed in an endeavour to assess some of the effects of climate. The upper limiting temperature of Plutella is approximately 40°C. and the lower limit for breeding purposes about 10°C. All stages of the moth can survive short periods of cold greater than 10°C., but it is believed that hibernation is normally accomplished in the adult stage. As the immature stages of the moth live in a specialised microclimate of high humidity, changes in the moisture content of the general atmosphere have little effect. Rain, if appearing at certain critical times in the life-cycle, may be a controlling agent.7. The most favourable areas for multiplication of the moth appear to be in the sub-tropics and warmer temperate zones. It is suggested that Plutella originated in the Mediteranean region.8. Even in the cooler temperate countries the climate would allow an indefinite increase in the moth. It is believed that an effective check on this multiplication is supplied by parasites.9. As the climate of England and New Zealand are essentially similar there is reason to suppose that the introduction of parasites from the former country will lead to eventual control being obtained in New Zealand.

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