Infestation

About: Infestation is a research topic. Over the lifetime, 8308 publications have been published within this topic receiving 82305 citations.

The use of sterile males to control populations of Queensland fruit fly Dracus tryoni (Frogg) (Diptera : Tephritidae) II. Field experiments in New South Wales

Abstract: In the field trials of sterile males against the Queensland fruit fly, Dacus tryoni, irradiated pupae of this species were distributed in three towns of western New South Wales in the period September 1962 to March 1965. All these towns and a number of others which served as controls had a previous history of heavy infestation by Dacus tryoni. The success of this method was estimated by comparing the rate of infestation of ripe fruit in treated and untreated towns. The first sign of success came in Manilla in spring (October) 1963 when 51.0% of the eggs deposited in loquats were estimated to be infertile compared with 6.7% in three control towns. However, our production of pupae at this stage was too low to maintain control in Manilla in the summers of 1962-63 and 1963-64. From late April 1963 to late March 1964 most of our production was released in the town of Warren. With a total release in this period of 5.7 x 106 pupae we achieved infestation rates of 2-8% in the summer fruit between early December 1963 and late March 1964, compared with infestation rates of 8-75% in three control towns during the same period. Towards the end of March 1964 the infestation rates began to rise in Warren apparently owing to the immigration of inseminated females along the Macquarie River. An infestation rate of 20% was reached in Warren in April 1964. Between early December 1964 and late March 1965 the rates of infestation in Warren were even more depressed, reaching values of 0 - 7.5% compared with 10-57% in the new control town of Baradine. The total number of pupae released within the town between August 1964 and March 1965 was 12.57 x l06. However, immigrants again brought the infestation up to 10% in April 1965 even though an additional 2.67 x l06 pupae had been distributed along the river for 6 km on either side of the town. In the same period (summer 1964-65) Dacus tryoni was eradicated from Trangie where its numbers had been brought down by trapping out the males with a male lure (Bateman 1966). No infestation was found from October 1964 to April 1965 after the release of 5.33 x l06 pupae between late August 1964 and late March 1965. The rate of infestation in the control town of Gilgandra which had also been treated with cue-lure in the previous summer rose from 0% on October 21, 1964 to 16.2% by April 23,1965. The method could be used to suppress incipient outbreaks of Dacus tryoni in southeastern Australia and even for the eradication of established populations where these are isolated and can be brought low by other means.

Infestation of Lymnaea stagnalis by digenean flukes in the Jeziorak Lake.

Abstract: The low number of articles on naturally trematode-infected snails results from the difficulty to obtain the quantitatively representative material The main aim of our study was to check which age (size) groups of snails are the most susceptible to trematode invasion Furthermore, we examined in which season the parasite prevalence is the highest We collected Lymnaea stagnalis individuals in a nearshore zone of the Jeziorak Lake (the longest Polish lake located in northern Poland) The shell height of the snails was measured and the infestation by trematode larvae was determined The logistic regression has shown that parasite prevalence increased significantly with the snail size (with the individuals >30 mm being the most infected), the distance from the beginning of the year (ie, month) and the vicinity of summer

Scale insects consistently affect roots more than shoots: the impact of infestation size on growth of eucalypt seedlings

Abstract: 1 Different infestation levels of the phloem-feeding scale insect, Eriococcus coriaceus Maskell (Hemiptera: Eriococcidae), consistently reduced root growth more than shoot growth in seedlings of Eucalyptus blakelyi Maiden (Myrtaceae). 2 Low levels of scale insect infestation significantly decreased root and lignotuber biomass but not shoot biomass. High levels of infestation, however, adversely affected all plant parts. Root and lignotuber biomass declined linearly, while the responses of stem and leaf biomass were nonlinear, with respect to increasing total insect load. 3 Plant responses to scale insect infestations may be explained by considering sapsucking insects as additional sinks that compete against plant sinks and both redirect and drain resources from the plant. 4 Scale insect populations exhibited strong density dependent effects, suggesting they were severely depleting resources within their hosts. Extensive shoot death at high levels of infestation may have contributed to insect population decline by causing scale insects to die prematurely or by reducing the availability of suitable feeding sites.