Biological control of sheep parasite nematodes by nematode-trapping fungi: In vitro activity and after passage through the gastrointestinal tract

The main method used for the control of gastrointestinal nematodes in sheep production is the application of chemotherapeutic agents, which often lead to the selection of parasites resistant to given active principles. Biological control can be considered a promising alternative, contributing to an increase in the efficacy of verminous control. We determined the in vitro activity and in situ survival of the predatory fungi Arthrobotrys musiformis and Arthrobotrys conoides during passage through the gastrointestinal tract of sheep after oral administration of conidia in microencapsulated form and as a liquid in natura. Initial in vitro tests showed that both fungi were efficient in the predation of trichostrongylid L3 larvae present in the faeces of sheep naturally infected with gastrointestinal nematodes. The fungi presented high nematophagous activity, which was 99.3% for A. conoides and 73.7% for A. musiformis. A. conoides did not survive passage through the gastrointestinal tract under the conditions of the present experiment. On the other hand, A. musiformis was reisolated after administration in either microencapsulated or liquid form, suggesting that this species is a promising alternative for the control of nematodes in sheep since it survives without any protection (in natura). © Springer 2005.

Biological control of Bradysia matogrossensis (Diptera : Sciaridae) in mushroom cultivation with predatory mites

Larvae of Sciaridae flies (Diptera) cause considerable damage to the mushroom Agaricus blazei (Murrill) ss. Heinemann in Brazil. Brazilian growers have had considerable difficulties in controlling this pest. The objective of this work was to test the effect of the predatory Laelapidae mite Stratiolaelaps scimitus (Womersley) as a control agent of Bradysia matogrossensis (Lane) in cultures of A. blazei. The work corresponded to an evaluation of the efficiency of that predator when released in boxes containing each about 15 L of commercial mushroom compost naturally infested with the pest. The results showed a significant effect of that predator on the population of B. matogrossensis. The release of either 665 or 1330 S. scimitus per box significantly reduced the pest population to levels that, according to grower's experience, apparently could not cause considerable damage. The positive results obtained warrant the conduction of complementary studies to determine the lowest rates of the predator that could still produce acceptable levels of control.

Improving photoprotection of Beauveria bassiana conidia for biological control of the cactus pest Dactylopius opuntiae in the semiarid region northeast of Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of Alternaria cassiae, Pseudocercospora nigricans, and soybean (Glycine max) planting density on the biological control of sicklepod (Senna obtusifolia)

The interactions of two fungal biocontrol agents, Alternaria cassiae and Pseudocercospora nigricans, and soybean planting density on sicklepod mortality and dry weight were studied in the field over 2 yr. The experimental field was divided into three equal areas: one without soybean and two where the soybean was sown in densities of 20 and 36 seeds per meter row with a 0.95-m row spacing. The fungi were sprayed alone or in a mixture at three growth stages of sicklepod plants grown at three levels of crop interference resulting from the three soybean planting densities. The fungal treatments were: an untreated control, A. cassiae (105 spores/m2), P. nigricans (3.3 g mycelium/m2), and the mixture of these two fungi. Sicklepod was at the cotyledonary leaf, two-leaf, and four-leaf stages when treated. Alternaria cassiae was most effective in reducing both sicklepod survival and dry weight. The mixture of P. nigricans and A. cassiae was generally comparable to but not better than A. cassiae alone in killing the weed (mortality) and reducing its growth (dry weight). Soybean density did not have significant effects on the mortality or the dry weight of sicklepod. Thus, there is no advantage to combining the highly effective biocontrol agent A. cassiae with the less effective P. nigricans or with soybean interference to control sicklepod. However, the results validate the efficacy of A. cassiae by itself as a bioherbicide.

Production and Use of Heteroptera Predators for the Biological Control of Eucalyptus Pests in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Palmistichus elaeisis (Delvare & LaSalle, 1993) (Hymenoptera: Eulophidae), possible agent for the biological control of Urbanus proteus (Linnaeus, 1758) (Lepidoptera: Hesperiidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biological control of phytophagous arthropods in the physic nut tree Jatropha curcas L. in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biological control of Glycaspis brimblecombei (Hemiptera: Aphalaridae) in eucalyptus plantations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of elevated atmospheric carbon dioxide on the biological control of coffee leaf rust under controlled conditions

The effect of elevated atmospheric CO2 concentration on biological control of coffee leaf rust, caused by Hemileia vastatrix, was evaluated by leaf disc assay, under controlled conditions. The biocontrol agents Bacillus subtilis, Bacillus pumilus and Lecanicillium longisporum were applied 24h before, 24h after, and simultaneously with the H. vastatrix on leaf discs (diameter of 1.5cm). The CO2 concentrations tested were: 380, 430, 700 and 1300ppm for B. subtilis and B. pumilus; and 380, 430, 670 and 1200ppm for L. longisporum. The antagonists were not affected by CO2 concentrations. B. subtilis was the most effective in controlling the disease when applied before and simultaneously with pathogen.

Biological control of root rot caused by Pythium aphanidermatum and growth promotion in hydroponic cucumber with microorganisms from mangrove

The prospection of biological control agents in similar environments to the microbe application improves the chances of microorganisms establishment added to the environment. The low survival of these beneficial microorganisms added to hydroponic environment is a problem for the growth promotion and root rot biological control success in hydroponic crops. Because of the environmental similarity between hydroponic systems and mangrove ecosystems, the aim of this work was to evaluate the ability of mangrove microbes to control root rot caused by Pythium aphanidermatum and to improve plant growth in hydroponic cucumbers. Among the 28 strains evaluated for disease control in small-hydroponic system using cucumber seedlings, Gordonia rubripertincta SO-3B-2 alone or in combination with Pseudomonas stutzeri (MB-P3A- 49, MB-P3-C68 and SO-3L-3), and Bacillus cereus AVIC-3-6 increased the seedlings survival and were subsequently evaluated in hydroponic cucumbers in a greenhouse. Bacillus cereus AVIC-3-6 protected the plants from stunting caused by the pathogen and Gordonia rubripertincta SO-3B-2 and Pseudomonas stutzeri MB-P3A-49 increased the plant growth. We concluded that microorganisms from mangroves are useful as biocontrol agents and for improving plant growth in hydroponic crops.

Biological control of the bronze bug, Thaumastocoris peregrinus, in eucalyptus plantations in Brazil

The bronze bug Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae) was detected in Brazil in 2008 and infested >180 000 ha of eucalyptus plantations in 2011. The bronze bug can cause a reduction of 10–15% in wood productivity after 2 years of heavy infestation. Although there is not an effective control method known, biological control is the main control strategy studied. An exotic egg parasitoid, Cleruchoides noackae (Hymenoptera: Mymaridae), was imported from Australia in 2012, reared in a laboratory and released in three Brazilian regions. Parasitoids were recovered at release points after 20–30 d. In 2013, preliminary evaluations demonstrated parasitoid establishment in these areas, and the parasitoid was recovered in adjacent areas after 1 year of release. Bioassays confi rmed egg parasitism of 15–20% by C. noackae. Other native natural enemies were studied. We found green lacewing Chrysoperla externa and predatory bugs Supputius cincticeps and Atopozelus opsimus preying on nymphs and/or adults of T. peregrinus. Another promising possibility is entomopathogenic fungi. Commercial formulations of Beauveria bassiana were tested with success in lab and fi eld conditions. Fusarium proliferatum and Paecilomyces cateniannulatus caused mortality of T. peregrinus in natural epizooties. After 5 years of research, it is possible to develop an integrated pest management system (IPM) for eucalyptus plantations based on biocontrol strategy for bronze bug.

Spatial and temporal population interactions between the parasitoids Cotesia flavipes and Tachinidae flies: considerations on the adverse effects of biological control practice

Biological control of Diatraea saccharalis is regarded as one of the best examples of successful classical biological control in Brazil. Since the introduction of the exotic parasitoid Cotesia flavipes, the decrease of D. saccharalis infestation in sugarcane fields has been attributed to the effectiveness of this agent. Recently, the native tachinid fly parasitoids (Lydella minense and Paratheresia claripalpis) have also been implicated in the success. Here, we investigated the spatial and temporal population interactions between C. flavipes and the tachinid flies, and provide a critical analysis of the biological control practice, focusing on the undesirable effects of introductions of exotic natural enemies. To investigate these questions, a large data set comprising information from two sugarcane mills located in the state of São Paulo, Brazil (Barra and Sao Joao Mills), was analysed. Analysis of the correlation between C. flavipes and tachinid fly population densities through time revealed that such populations were inversely correlated in the Sao Joao Mill and not correlated in the Barra Mill. Logistic regressions were computed to investigate the proportion of sites occupied by the parasitoid species at both mills as a function of time. An increasing trend in the proportion of sites occupied by C. flavipes was observed, with a concomitant decrease of the sites occupied by tachinid flies. This effect was more intense in the Sao Joao Mill. Thus, there is a convincing possibility that constant releases of C. flavipes decreased the tachinid fly populations, resulting in an undesirable effect of biological control practice.

Evaluation of the biological control by the yeast Torulaspora globosa against Colletotrichum sublineolum in sorghum

The yeasts are microorganisms with great potential for biotechnological applications in diverse areas. The biological control of phytopathogens by yeasts has showed satisfactory results under laboratory conditions, and it has already produced commercial formulations. With this as focus, this work aims to perform in vitro and in vivo evaluations of the action of a Torulaspora globosa yeast strain (1S112), isolated from sugarcane rhizosphere, against the phytopathogenic mold Colletotrichum sublineolum, the causative agent of anthracnose in sorghum. In vitro experiments included the antagonism test in Petri dishes with morphological hyphal evaluation; yeast killer activity; siderophore, volatile compound and hydrolytic enzyme production. In vivo experiments were conducted in greenhouse conditions with a sorghum variety susceptible to C. sublineolum by evaluating the anthracnose disease for 6 weeks. The results indicated that the yeast strain significantly controlled the fungal growth, either in vitro or in vivo. The strain of T. globosa exhibited killer activity against two sensitive strains, which is a novel capacity for this species. The yeast did not produce siderophores, volatile compounds or hydrolytic enzymes, although it has reduced the mycelial growth, resulting in hyphal deformities but not cell death. The yeast controlled the anthracnose disease in sorghum, either inoculated before or after the fungal spores, suggesting that the competition for space and nutrients to dominate the mold and killer toxin production, altering the hyphal morphology, are mechanisms utilized by the yeast in the biocontrol.

Crescimento e esporulação de duas espécies de arthrobotrys corda em diferentes meios de cultura e dois ambientes

The researches on the biological control of nematodes with nematophagous fungi has been intensified in recent years. The knowledge of the ecological conditions for the growth and sporulation of these fungi is a prerequisite for attainment of pure cultures needed to attend the demand for formulation of these organisms. With the objective to evaluate the micelial growth and sporulation of Arthrobotrys musiformis and A. oligospora in two environments (B.O.D at 25 +/- 1 degrees C and the environment of the Laboratory), 20 cultures media prepared with common materials found in the communities and industrialized media such as mycological agar, PDA and CMA were evaluated. The media were tested in Petri dishes, being the micelial growth of the fungi evaluated daily, during six days. The measured sporulation at the end of the experiment was done by estimation of the number of conidia/Petri dish. The experiment was carried out in a random design following a factorial arrangement of 20 x 2 x 2, corresponding to 20 media, two fungi and two environments, with five replicates. The variance analysis of the data evidenced significant statistical difference by the F Test, at 1% probability, among media x fungi x environment interaction. Fifty percent of the tested media provided the adequate micelial growth of A. musiformis and there was no statistical difference among them, namely: cassava meal (FM), sweet starch (PD), "corn meal agar" (CMA), oat in fine flakes (AFF), agar-water + dextrose (AA+D), mycological agar (AM), potato dextrose agar (BDA), meal of maize (FMI), flour of wheat (FT) and wheat for kibble (TK). In relation to A. oligospora, 75% of the tested media promoted the maximum growth of the fungus, which are: AFF, AM, FM, PD, CMA, AA+D, BDA, FT, TK, the water from the decoction of rice (AAZ), rice in grains (AZG), triturated rice (AZT), thread flour (FR), oats flour (FA), oats in thick flakes (AFG) and flour of maize (FU). In relation to the sporulation the media that had better role for A. musiformis, in decreasing order, were: FR, TK, AFG, BDA, FA, AFF, AM, FMI, AZT and FM, varying between 1,01 x 10(6) and 1,4 x 10(4) conidia/Petri dish. For the A. oligospora sporulation, the CMA medium provided the maximum level with an estimated average of 5,7 x 10(6) conidia/Petri dish. In the general, the best media for the micelial growth and sporulation of A. musiformis had also been the best for A. oligospora. However, some that had been the best for the A. oligospora did not had been efficient for the micelial growth or the sporulation of A. musiformis, indicating that the isolate of A. musiformis in case is more demanding than that A. oligospora one. The evidences from the study indicate that, in Jaboticabal, São Paulo state, the growth and the sporulation of these fungi do not demand special chambers. Some adaptations of an environment at the laboratory, enough to obliterate the light are sufficient.