Biological Control Laboratory Research Articles

Ovicidal and Larvicidal Activity of Conidia and Blastospores of Paecilomyces fumosoroseus (Deuteromycotina: Hyphomycetes) Against Bemisia argentifolii (Homoptera: Aleyrodidae) with a Description of a Bioassay System Allowing Prolonged Survival of Control Insects

Fungi are the only effective entomopathogens of members of the Aleyrodidae and other homopterans because of the piercing and sucking feeding strategy of these insects. The laboratory assessment of the entomopathogenic activity of fungi often requires a prolonged period of observation. Leaf quality can be the limiting factor in bioassays of fungi against whiteflies that require longer observation periods or those that require conditions that are as close to natural ones as possible. A bioassay system is described that utilizes rooted cabbage leaves infested with the highly polyphagous whitefly, Bemisia argentifolii . Using this method, discriminating dosages of aerial conidia and blastospores of two isolates of Paecilomyces fumosoroseus (Pfr) were bioassayed against eggs and nymphs of B. argentifolii . Low, but significant, mortality (10-20%) of eggs was observed 14 days after exposure to 3.8 104 blastospores/cm2 for the Pfr 97 and European Biological Control Laboratory (EBCL) Pfr 42 isolates. Additionally, the majority of crawlers that had hatched from treated eggs died on the surface of the leaves. Exposure of early second-instar nymphs of B. argentifolii to 3.8 103 conidia or blastospores/cm2 of Pfr 97 resulted in mortalities of 27 and 77% respectively. Identical dosages of conidia and blastospores of the Pfr 42 isolate resulted in mortalities of 59 and 68% respectively. The bioassay method described enables the comparative evaluation of entomopathogenic fungi against whiteflies under diverse biotic and abiotic conditions.

Effect of some preparates on soil microflora on the basis of soil bioassay

Trials for control of soil-borne plant pathogen fungi with biological and chemical fungicide preparates have been carried out in our Biological Control Laboratory for more than 10 years. During all these experiments soil bioassay was always carried out in order to observe the soil microflora. Here we mention one trial which confirms the general opinion that chemical treatments significantly change the soil microflora. The tested biological fungicide did not cause such changes.

Gene Flow in Colonizing Hippodamia variegata Ladybird Beetle Populations

From the Department of Entomology, Iowa State University, Ames, IA 50011. This is Journal paper no. J15929 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa; project no. 2949. Thanks to Deb Nelson and Julie Gould, USDA-APH1S Biological Control Laboratory, Niles, Michigan, for supplying laboratory-reared beetles, and Donna Ellis, University of Connecticut, and Lisa Tewkesbury, University of Rhode Island, for collecting wild beetles. This research was partly supported by USDA-APHIS grant no. 12-34-81-016&GR and CSRS USDA grant 94-373120673. Address reprint requests to Dr. E. S. Krafsur at the address above.

Desenvolvimento de Supputius cincticeps (Heteroptera, Pentatomidae) alimentado com larvas de Zophobas confusa, Tenebrio molitor (Coleoptera, Tenebrionidae) e Musca domestica (Diptera, Muscidae)

Egg viability and nymphal development of the predatory bug Supputius cincticeps (Stal, 1860) were evaluated during two generations in the Biological Control Laboratory of the Nucleo de Biotecnologia Aplicada a Agropecuaria (Bioagro/UFV) in Vicosa (Minas Gerais, Brazil) at 24.72±1.10oC and photophase of 12 hours. Three treatments were represented by S. cincticeps fed with Zophobas confusa Gebien, 1906, Tenebrio molitor Linnaeus, 1758 and Musca domestica Linnaeus, 1758 larvae. Higher egg viability of this predator was found when the preys were Z. confusa and T. molitor, 74.46% and 80.91 %, than in M. domestica, 57.02%, but incubation period showed no differences between preys. Shorter nymphal development and higher nymphal viability were found with Z. confusa and T. molitor than with M. domestica. Higher weight increase was found for nymphs which originated males and females in the second generation specialy with the first two preys.

Microbial control of soil‐borne pathogens in Hungary1

Biological control of soil‐borne pathogens has been the aim of the Biological Control Laboratory in Hódmezövásárhely since 1982. In Hungarian glasshouses (this means areas both under glass and plastic foil cover), the growing medium is still the natural soil or mixtures based on soil. This is the reason why soil‐borne pathogens, such as species of Fusarium, Sclerotinia, Pythium, Botrytis, Rhizoctonia and Alternaria, cause increasing problems, especially at sites where there has been intensive continuous cropping for many years. Soil steaming is very expensive, while methyl bromide and other soil disinfectants are harmful for the environment and especially for the soil microflora. All this favours the introduction of biological control against soil‐borne plant diseases. After laboratory tests, experiments have been carried out over a 9‐year period, with good results, on several Trichoderma species and strains in relation to practically all glasshouse crops (capsicum, lettuce, tomato, ornamentals, etc.) and in some field crops also. Since 1986, experiments have been done with Finnish‐originated strains of Streptomyces griseoviridis, then with the preparation Mycostop which was developed from this actinomycete. These were carried out on ornamentals, on vegetables and on some cereals. The preparation was especially effective against Fusarium spp. but also against other pathogens.

Die Stellung der biologischen Schädlingsbekämpfung im integrierten Pflanzenschutz1

AbstractThe role of biological control in pest management. Biological control comprises both, the addition of new biotic elements to actively reduce pest organisms and the protection and furthering of beneficial organisms already present. Manipulation of biotic antagonists can be considered as one of the constructive principles of the total potential of integrated control schemes (fig. 1). Each single case uses different elements (cp. fig. 2 and 3). The place of “biotechnical control” between technical and biological methods is defined and briefly exemplified (fig. 1). ‐ After discussing the programme for the Darmstadt biological control laboratory the attention is centered on such cases which do not fit into the frame of the “economic injury level”. Neither the life saving effect of vector control nor the protective and social value of silviculture and agriculture in densely populated regions can normally be calculated on a monetary basis. Nevertheless, the importance of less expensive integrated control measures is thought to increase in future. It will be applied where medical and ecological reasoning leave no other possibility and where agriculture becomes part of conservation.

Life History and Sex Determination in the Diaspine Scale,Pseudaulacaspis pentagona(Targ.) (Coccoidea)

The increasing body of knowledge about the armored scales is beginning to reveal manv unique aspects in the life cycles of these highly specialized insects. Such information is not only of value to the entomologist and those concerned with the control of scales but is also becoming important in such diverse fields as genetics, ecology, cytology, and physiology; armored scales may well find an expanding place in the laboratory as subjects for researches in a variety of fields.Pseudaulacaspis pentagona(Targ.) has one of the most unusual, yet to date one of the best understood life cycles of the armored scales. Various aspects of its biology have been described by Berlese (1910), Smit (1953), Dustan (1953), and Monti (1955). Accounts of its natural enemies or biological control programs have been given by Berlese (1910) for Italy, by Ogilvie (1928) and Simmonds (1955) for Bermuda, by Bennett (1956) for Trinidad, and Clausen (1956) for Florida.P. pentagonais a pest of economic importance on a wide variety of hosts throughout an extekive geographic distribution (Anon., 1956), and has been cultured extensively in the biological control laboratory for the mass-rearing of scale parasites and predators. Recent investirzations of the sex determining mechanik and chromosome behaviour (Brown and Bennett, 1957) have arain shown unusual processes and relationships, some of which appear to occur in many other species of armored scales. It is the purpose of this paper to describe the life cycle ofP. pentagonaas it is known from field and laboratory studies and from cytological and genetic investigations.