Biological Control

The ability of Brevibacillus brevis to influence development of disease on tomato caused by Fusarium oxysporum f.sp. lycopersici was investigated using plants raised in Petri dish microcosms and in pots in the glasshouse. Development of symptoms on both microcosm-and ...

Entomopathogenic nematodes (EPNs) of the genera Heterorhabditis and Steinernema are obligate and lethal insect parasites. They have the greater potential to be developed as a microbial agent for the management of various insect pests of orchard, vegetables, ornamental plants and turf grasses. The third stage juvenile i.e. the infective juvenile along with symbiotic bacteria (Xenorhabdus spp. in Steinernema spp. and Photorhabdus spp. in Heterorhabditis spp.) enters into the insect body through natural openings or sometimes by penetration through intersegmental membrane. The relationship between nematode and bacteria is an example of true mutualism and from this relation both the organisms are benefited. This nematode-bacterium complex causes the death of insect pests within 24–72 hours. Mass rearing of Steinernematid and Heterorhabditid nematodes can be done in vivo in insect hosts and in vitro in solid medium or in liquid medium. For in vivo production Galleria mellonella larvae are...

Endophytic bacteria isolated from internal tissue of surface sterilized jatropha curcas L. leaves, stem, frouts and roots. Collected from field plots produced secondary metabolites in nutrition broth media (NB) that were highly toxic to Meloidogyne spp. especially strains SJS54 followed by RJS175 were highly active among 23 strains producing secondary metabolite toxic to Root-knot nematodes. The mechanism of action of the toxic metabolites produced by the non-pathogenic strains SJS54 and RJS175 with proven biological control of Meloidogyne spp in Syracuse glass experiments was investigated. These metabolites reduced Meloidogyne spp mobility within 6-12 h of exposure. After 6 h, approximately ±50% of juveniles was inactivated. But with exposure of 12 h 80-90% of the juveniles were dead. The SJS54 and RJS175 toxicity were highly effective towards migratory parasites. Most of nematodes have been shown body wall degradation caused by hydrolytic enzymes produced by endophytic bacteria, a...

Infection with gastrointestinal nematodes, particularly Haemonchus contortus, is a major constraint to goat production in the southeastern United States. Non-anthelmintic control alternatives are needed due to increasing resistance of these nematodes to available anthelmintics. Two studies were completed in Central Georgia in August 1999, and April-May 2000, using Spanish does naturally infected with Haemonchus contortus, Trichostongylus colubriformis, and Cooperia spp. to evaluate effectiveness of nematode-trapping fungi as a biological control agent. In the first experiment, five levels of Duddingtonia flagrans spores were mixed with a complete diet and fed once daily to the does (three per treatment) in metabolism crates. The treatment concentrations were (1) 5 x 10(5), (2) 2.5 x 10(5), (3) 10(5), and (4) 5 x 10(4) spores per kilogram body weight (BW), and (5) no spores. Fungal spores were fed for the first 7 days of the 14-day trial, and fecal samples were collected daily from i...

Beauveria bassiana colonizes insect hosts initially through a yeast phase, which is common in some artificial liquid cultures, but not reported on artificial solid media. We describe a yeast-like phase for B. bassiana isolate 447 (ATCC 20872) on MacConkey agar and its virulence toward Diatraea saccharalis and Tetranychus urticae. The yeast-like cells of B. bassiana developed by budding from germinating conidia after 24-h incubation. Cells were typically and fungal colonies were initially circular and mucoid, but later were covered with mycelia and conidia. Ability to produce yeast-like cells on MacConkey medium was relatively common among different B. bassiana isolates, but growth rate and timing of yeast-like cell production also varied. Metarhizium anisopliae and Paecilomyces spp. isolates did not grow as yeast-like cells on MacConkey medium. Yeast-like cells of B. bassiana 447 were more virulent against D. saccharalis than conidia when 107 cells/ml were used. At 108 cells/ml, the estimated mean survival time was 5.4 days for the yeast suspension and 7.7 days for the conidial suspension, perhaps due to faster germination. The LC50 was also lower for yeast than conidial suspensions. Yeast-like cells and conidia had similar virulence against T. urticae; the average mortalities with yeast-like cells and conidia were, respectively, 42.8 and 45.0%, with 107 cells/ml, and 77.8 and 74.4%, with 108 cells/ml. The estimated mean survival times were 3.6 and 3.9 for yeast and conidial suspensions, respectively. The bioassay results demonstrate the yeast-like structures produced on MacConkey agar are effective as inoculum for B. bassiana applications against arthropod pests, and possibly superior to conidia against some species. Obtaining well-defined yeast phase cultures of entomopathogenic hyphomycetes may be an important step in studies of the biology and nutrition, pathogenesis, and the genetic manipulation of these fungi.

Colonization of soybean roots by the biocontrol fungus Verticillium lecanii was studied in vitro and in situ. For in vitro experiments, V. lecanii was applied to soybean root tip explant cultures. Four weeks after inoculation, the fungus grew externally on at least half of the roots (all treatments combined), colonizing 31% to 71% of root length (treatment means). However, when a potato dextrose agar plug was available as a nutrient source for the fungus, root tips inoculated soon after transfer were not colonized by V. lecanii unless Heterodera glycines was present. Scanning electron microscopy of colonized roots from in vitro cultures revealed a close fungus-root association, including fungal penetration of root cells in some specimens. In the greenhouse, soybeans in sandy soil and in loamy sand soil were treated with V. lecanii applied in alginate prills. The fungus was detected at greater depths from the sandy soil than from the loamy sand soil treatment, but fungus population n...

Effect of prey density on biology and functional response of green lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) was studied in the laboratory of Entomology Section of Agricultural Research Institute, Dera Ismail Khan at 25±1ºC, 65±5% RH and 10:14 light : dark regime. Newly emerged larvae of C. carnea were fed 20, 30, 40, 50, 60, 70, 80, 90 and 100 fresh eggs of Sitotroga cerealella (Lepidoptera: Gelechiidae) in 9 cm petri dishes. It was observed that the prey density had a significant effect on positive consumption rate, development and fecundity of C. carnea. In general maximum consumption with shortest developmental time, maximum fecundity and longest adult longevity were observed as prey density increased. In all treatments, predatory potential was high when the prey density was raised. Daily predation rate of C. carnea increased slowly during the first two instars and reached to its peak in the third larval instar. Although, C. carnea completed its developme...

Mimosa, Mimosa pigra L., is renowned for producing an abundance of seeds, many of which remain in the population as a persistent seed bank. Integrated control programs have been effective in reducing the above-ground cover of mimosa but little is known about its effect on the soil seed-bank. The viability of mimosa soil seed banks following integrated control was investigated

Bacterial strains isolated from grass foliage were tested for inhibition of brown patch disease, caused by Rhizoctonia solani Kühn, on detached blades and potted seedlings of tall fescue (Festuca arundinacea Schreb. cv. Kentucky 31). Stenotrophomonas maltophilia strain C3 prevented growth of the fungus on leaf blades and reduced the severity of necrosis on seedlings. When strain C3 was tested on

The studies primary objective was to establish whether there was a difference in ciliary activity upon immersion in the aqueous smoke extracts from filtered and non-filtered cigarettes. The result was that there was indeed a difference in ciliary activity. The cilia’s BPM reduction was much more substantial within the specimen when immersed in aqueous extracts from a non-filtered cigarette than in comparison with the control of seawater as well as aqueous smoke extracts from the filtered cigarette. The BPM of the cilia immersed within the seawater was greater than that of the specimen immersed within the non-filtered cigarette aqueous extracts, however it is to no degree as detrimental as the non-filtered extract. This observation deduces the principle idea that smoking a cigarette without a filter has much more of a substantial effect on the ciliary activity, and likewise that there are similar, yet less substantial impediments of ciliary activity within the process of smoking cigarettes with filters opposed to not smoking at all. In over all aspects of the study, the results were very consistent with the predictions and proposed hypothesis of impeded ciliary activity which allow it remain highly complimentary in regards to studies conducted with similar parameters and goals such as those highlighted throughout this paper.

Biological cycle of Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) feeding on several preys Chrysoperla externa (Hagen) is an important insect predator on several agricultural pests. Effect of feeding on several preys on life span of C. externa was studied under laboratory conditions (27 ± 2 ºC mean temperature and 60 ± 5 % R.H.). Each of the following preys was daily

Sclerotium cepivorum, is worldwide destructive soil borne fungal pathogen and has been reported attacking onion and other Allium species causing considerable damage to the host under congenial environments in Egypt and other regions. Recently, this species was isolated from North Egypt after long settlement in south Egypt. Many attempts were used to control onion white rot disease caused by this pathogen. In the present study three fungicides viz. procimidone (sumisclex®25), vinclozolin (ronilan) and tolclofos-methyl (rizolex) were used against Sclerotium cepivorum and compared with a range of non chemical treatments including five antagonistic fungi, two antagonistic bacteria, two essential oils and fine red onion waste (ROW) in naturally infested area to evaluate their effects on the incidence and severity of onion white rot disease under field conditions. Among all fungicides tested, it was found that sumisclex®25 was the best chemical treatment giving 14.81% reduction in disease incidence and 13.38% severity. While, Gliocladium virens achieved the best results of reducing disease incidence giving 8.89% and disease severity by 8.38%. On the other hand, Pseudomonas fluorescens and Bacillus subtilis reduced disease incidence, giving 21.48 and 22.96%, respectively and high reduction in disease severity by 19.01 and 21.23% respectively. Among all tested essential oils, cinnamon oil considered the best treatment giving 32.59% disease incidence and 28.88% severity. While, ROW was the best treatment reducing the disease incidence, giving 8.15% disease severity.

Peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae) is native to South and South-East Asia. It is a polyphagous species and has a high reproductive potential (approx. 600 eggs in a lifetime), high biotic potential, i.e., several generations of progeny per year. The species has the rapid dispersal ability and can be active throughout the year. Its establishment may have a serious impact on the environment following the initiation of chemical and/or biological control programmes. B. zonata is of quarantine significance to EPPO (European and Mediterranean Plant Protection Organization) countries and it is classified on the A1 list of pests recommended for regulation as quarantine pests by Centre for Agriculture and Biosciences International (CABI). The present study initiates an attempt to identify the larval (3rd instar) salivary gland polytene chromosome arms of B. zonata using Olympus phase contrast microscope CX 41. A photographic representation of the polytene chromosomes of this species associates with identifying tips as well as well defined characteristics of each  polytene chromosome arms are described. Five long chromosomes with their identifying tips are recognized in each polytene nucleus.
Polytene chromosomes are of special interest to construct a Genetic Sexing Strain (GSS) of a pest species and it can play an important role for the successful application of Sterile Insect Technique (SIT) in field application as part of the biological control programme under Integrated Pest Management (IPM) scheme.

Several stipoid grasses of temperate South American origin have invaded Australia. One of these, Nassella trichotoma, is considered the most important grass weed of pas- tures in south-eastern Australia, while another, Nassella neesiana is viewed as a serious threat to native Australian grasslands. Blue heliotrope, Heliotropium amplexicaule, a toxic perennial broad-leaf weed, originates in the same area of South America, and is rapidly spreading in parts of south-eastern Australia. Landholder groups were formed to seek research into better control methods of Nassella tussock grasses and blue heliotrope, respectively, and in 1998 both groups were successful in lobbying for funds to investigate the potential of biological control. The Nassella project is the first one aimed at classical biological control of a grass weed and, based on preliminary surveys, will concentrate on pathogens. A similar survey on blue heliotrope has indicated that insects provide the best prospects for contro...