Bionomics and the predicted distribution of the aphid Brachycaudus rumexicolens (Hemiptera: Aphididae)

1999 ◽  
Vol 89 (1) ◽  
pp. 97-106 ◽  
Author(s):  
J.K. Scott ◽  
P.B. Yeoh
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Late Summer ◽  
Control Agent ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Rate Of Increase ◽  
Summer Temperatures ◽  
Recent Arrival ◽  
Cool Summer

AbstractDevelopment rates of the aphid, Brachycaudus rumexicolens (Patch), a recent arrival in Australia and a potential biological control agent against weeds in the family Polygonaceae, were measured over a range of constant temperatures. The theoretical lower limit for development is 6.4°C and the upper limit 32°C. Maximum fecundity per day was reached at 19°C. The rate of increase peaked at about 28°C giving a population doubling time of less than two days. These values were used with the current distribution to develop a CLIMEX model to predict the potential world distribution of the aphid. The model predicts that the aphid has suitable periods of population growth in autumn and spring, and that survival is unlikely over summer in most of south-western Australia where the aphid has the potential to contribute to the biological control of the polygonaceous weeds, Emex and Rumexspecies. The model predicts that years with cool summer temperatures and late summer rains in south west Australia, such as in 1990 when the aphid was first abundant, will be particularly suitable for aphid development. These conditions occurred twice between 1985 and 1995. To increase the effectiveness of the aphid as a biological control agent of weeds in other years, augmentation by provision of alternative hosts and/or the release of mass reared individuals during autumn is proposed.

scholarly journals Diapause behaviour of Zygogramma bicolorata (Coleoptera: Chrysomelidae), a biological control agent for Parthenium hysterophorus (Asteraceae), in Bangalore, India

1993 ◽  
Vol 83 (3) ◽  
pp. 383-388 ◽  
Author(s):  
K. P. Jayanth ◽  
Geetha Bali
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Extended Period ◽  
Control Agent ◽  
Parthenium Hysterophorus ◽  
Continuous Exposure ◽  
Zygogramma Bicolorata ◽  
Before And After ◽  
Summer Temperatures ◽  
Over Time

AbstractZygogramma bicolorata Pallister was introduced for biological control trials against the weed Parthenium hysterophorus (Asteraceae) in India. The insect entered diapause over an extended period of time between July and December in Bangalore. Diapausing adults burrowed into the soil, and emerged in May–June with the commencement of monsoon rains. Percentage diapause increased over time, peaking at 72% during November. Non-diapausing adults were capable of breeding, under laboratory conditions, during the winter. Some adults bred both before and after diapause, during two consecutive years. Soil moisture played an important role in providing the conditions for burrowing or emerging from the diapause chambers. The studies also showed that diapausing adults had to be exposed to the high summer temperatures, for termination of the diapause. It was possible to break diapause by continuous exposure to 30°C, 35°C and 40°C for 22 days, nine days and 10 hours, respectively, during February–March, about three months after its inception. This method can be used to initiate mass multiplication for carrying out releases early in the season.

scholarly journals Effect of Temperature on Life History and Parasitization Behavior of Trichogramma achaeae Nagaraja and Nagarkatti (Hym.: Trichogrammatidae)

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 482
Author(s):  
Modesto del Pino ◽  
Juan Ramón Gallego ◽  
Estrella Hernández Suárez ◽  
Tomás Cabello
Keyword(s):  
Biological Control ◽  
Life Table ◽  
Biological Control Agent ◽  
Control Agent ◽  
Intrinsic Rate Of Increase ◽  
Adult Longevity ◽  
Type I ◽  
Net Reproductive Rate ◽  
Rate Of Increase ◽  
Trichogramma Achaeae

Trichogramma achaeae Nagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae) is currently used as biological control agent for several lepidopteran pests. Knowledge of thermal requirements is essential to optimize its rearing procedures and inundative releases. The biological characteristics and two-sex life table parameters of T. achaeae were determined at five constant temperatures (15, 20, 25, 30, and 35 °C) using Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. T. achaeae was able to develop and survive from 15 °C to 30 °C, but not at 35 °C. Temperature significantly affected the preadult development time and adult longevity, decreasing when temperature increased from 15 °C to 30 °C. Temperature significantly altered the sex ratio, being female biased between 15 °C and 25 °C. Age-stage, two-sex life table analysis indicated that net reproductive rate (R0) was highest at 20 °C. Both the intrinsic rate of increase (r) and finite rate of increase (λ) increased with increasing temperature, while the mean generation time (T) decreased significantly. In addition, functional response of T. achaeae was studied, being significantly affected by temperature and host egg density, displaying a Holling type-I at 15 °C and a Holling type-II at 25 °C. The relevance of these results is discussed for the use of T. achaeae as biological control agent.

Kill rates by rabbit hunters before and 16 years after introduction of rabbit haemorrhagic disease in the southern South Island, New Zealand

2014 ◽  
Vol 41 (2) ◽  
pp. 136 ◽  
Author(s):  
Carlos Rouco ◽  
Grant Norbury ◽  
Dave Ramsay
Keyword(s):  
Biological Control ◽  
New Zealand ◽  
Biological Control Agent ◽  
Negative Relationship ◽  
Control Agent ◽  
Geographic Region ◽  
Instantaneous Rate ◽  
Rate Of Increase ◽  
Rabbit Haemorrhagic Disease ◽  
Haemorrhagic Disease

Context European rabbits (Oryctolagus cuniculus) are serious economic and environmental pests in Australia and New Zealand. Since the illegal introduction of rabbit haemorrhagic disease virus (RHDV) in New Zealand in 1997, the disease has persisted in most rabbit populations, with major epizootics occurring usually each autumn. Aims We evaluated the efficacy of the virus as a biological control agent in the southern South Island. Methods We used an index of rabbit abundance (kills per hunter) based on a region-wide annual rabbit-hunting competition to evaluate rabbit population trends 7 years before and 16 years after the first outbreak of RHD. We also evaluated the influence of rainfall and temperature in the preceding year on post-RHD trends in the index. Key results Kill rates declined by 60% following the initial epizootic. They remained low for the following 3 years and then increased steadily to intermediate levels punctuated by occasional declines. The instantaneous rate of increase in kill rates during the increase phase was low, but above zero (0.04 per year). No relationship between kill rates and rainfall was apparent, but there was a negative relationship between kill rates and winter temperature in the preceding season. Conclusions The kill-rate data obtained from this hunting competition suggest that RHD still appears to be killing rabbits. Every 2–3 years over the past decade, kill rates have been as low as they were when government rabbit-control programs were in place before RHD arrived, but the efficacy of RHD as a biological control agent is waning compared with the first outbreaks of the disease. This concurs with findings based on spotlight counts. Implications The data collected from this hunting competition are a good example of how ‘citizen science’ can be used to capture large volumes of pest-monitoring data from a wide geographic region for very little cost. The information is a valuable addition to understanding the effects of a major wildlife disease.

scholarly journals The seasonal abundance of the newly established parasitoid complex of the Eucalyptus tortoise beetle (Paropsis charybdis)

2003 ◽  
Vol 56 ◽  
pp. 51-55 ◽  
Author(s):  
D.C. Jones ◽  
T.M. Withers
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Late Summer ◽  
Egg Parasitoid ◽  
Control Agent ◽  
Early Summer ◽  
Seasonal Abundance ◽  
Eucalyptus Nitens ◽  
Promising Alternative ◽  
Tortoise Beetle

Enoggera nassaui has been the key biological control agent of the eucalyptus tortoise beetle Paropsis charybdis since 1987 In 2001 a second egg parasitoid Neopolycystus insectifurax as well as an obligate hyperparasitoid of E nassaui Baeoanusia albifunicle were detected in New Zealand Monitoring of Eucalyptus nitens plantations in the central North Island revealed that 50 of P charybdis eggs in half the sites were parasitised by E nassaui in early summer However later in the season this was followed by a reduction to 10 parasitism by E nassaui the remaining 40 of parasitised eggs being hyperparasitised by B albifunicle Neopolycystus insectifurax parasitised an additional 35100 of eggs in late summer This indicates that while B albifunicle has the potential to severely reduce the effectiveness of E nassaui the new agent N insectifurax is a promising alternative

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