Search

Stress the use of safer options such as biological control to avoid the hazards of chemical nematicides. UV irradiation has been used to induce mutations and improve protease overproduction. All mutants recorded significant decreases in nematode-related parameters when compared with the wild type and control. Mutant number one (M1) achieved high protease activity about 2.5 fold. At two concentrations of the wild type Bacillus cereus and their mutants effect on percentage mortality of Meloidogyne incognita juveniles. M1 achieves the highest mortality, 99.33 %, and achieved greatest reductions in the number of juveniles in soil, juveniles/5 g root, galls, and egg-masses recorded 89.76 %, 90.16 %, 85.29 %, and 89.11 %, respectively. M1 achieved the best increase of the growth parameters of plant length, number of branches, number of leaves, and fresh weight of leaves recorded 54.35 %, 71.45 %, 169.44 %, and 256.17 %, respectively. These results are in harmony with those of leaves water soluble-protein electrophoretic patterns after one month and the end of the application, which showed that the plant exposed to M1 exhibited the highest number of bands in both stages of application and appeared unique band at M. W 55kDa after one month of application. [ABSTRACT FROM AUTHOR]

The current study evaluated the efficacy of indigenous isolates of entomopathogenic fungi against the third larval instar of tomato leaf miner (Tuta absoluta Meirick; Lepidoptera: Gelechiidae). Four virulent isolates were subject to morphological and molecular identification and they were identified as; Beauveria bassiana isolate Hammad-R7 (Sudan) accession (MN598666); Beauveria bassiana isolate-Sud-afro-18ITS accession (MK046654); Beauveria bassiana isolate Sud-afro-2oITS accession (MK046652) and Purpureocillium lilacinum isolate Khartoum accession (MK046655). Efficacy test was done by larval dipping in the fungal suspension along with the commercial product Eco-Bb®. Mycosis test was performed to confirm the growth of fungus from the cadaver. Treated larvae died within three days after the appearance of the symptoms. The four indigenous isolates showed medium mortality responses (LT50 ranged between 4.1–4.3 days) close to or slightly even better than that induced by the commercial product ECO-Bb (LT50 4.2 days) however three of them induced superior responses (LT90 ranged between 9.5–11.7 days) to the commercial product ECO-Bb (LT90 14.4 days) at higher doses measured at the LT90. Endophytic capability of the isolates was tested by seed dipping and soil drenching methods and the fungal mycelia was detected microscopically in the leaves and stems without apparent negative effects on plant growth. The current results indicate the promising potential of these isolates in the regulation of T. absoluta. [ABSTRACT FROM AUTHOR]

Background: The current status of insecticide resistance in mosquitoes and the effects of insecticides on nontarget insect species have raised the need for alternative control methods for malaria vectors. Predation has been suggested as one of the important regulation mechanisms for malaria vectors in long-lasting aquatic habitats, but the predation efficiency of the potential predators is largely unknown in the highlands of western Kenya. In the current study, we examined the predation efficiency of five predators on Anopheles gambiae s.s larvae in 24 hour and semi-field evaluations. Methods: Predators were collected from natural habitats and starved for 12 hours prior to starting experiments. Preliminary experiments were conducted to ascertain the larval stage most predated by each predator species. When each larval instar was subjected to predation, third instar larvae were predated at the highest rate. Third instar larvae of An. gambiae were introduced into artificial habitats with and without refugia at various larval densities. The numbers of surviving larvae were counted after 24 hours in 24. In semi-field experiments, the larvae were counted daily until they were all either consumed or had developed to the pupal stage. Polymerase chain reaction was used to confirm the presence of An. gambiae DNA in predator guts. Results: Experiments found that habitat type (P < 0.0001) and predator species (P < 0.0001) had a significant impact on the predation rate in the 24 hour evaluations. In semi-field experiments, predator species (P < 0.0001) and habitat type (P < 0.0001) were significant factors in both the daily survival and the overall developmental time of larvae. Pupation rates took significantly longer in habitats with refugia. An. gambiae DNA was found in at least three out of ten midguts for all predator species. Gambusia affins was the most efficient, being three times more efficient than tadpoles. Conclusion: These experiments provide insight into the efficiency of specific natural predators against mosquito larvae. These naturally occurring predators may be useful in biocontrol strategies for aquatic stage An. gambiae mosquitoes. Further investigations should be done in complex natural habitats for these predators.

A total of 72 isolates of root-associated/endophytic (RAE) bacteria were isolated from peanut plants grown in the main producing areas of 6 provinces in China. The 16S rRNA gene sequences of these isolates were determined and phylogenetic analyses revealed that 72 isolates belonged to the classes Bacilli (49 isolates) and Gammaproteobacteria (23 isolates). The majority of RAE bacteria in Bacilli belonged to 2 genera, Bacillus and Lysinibacillus (48 and 1) while those in Gammaproteobacteria belonged to the genera Enterobacter, Serratia, Stenotrophomonas, and Pseudomonas (7, 11, 3 and 2 isolates, respectively). This is the first report of Lysinibacillus xylanilyticus isolate as biocontrol agent against AFs. All of the selected RAE bacteria showed inhibitory activities against Aspergillus parasiticus ( A. parasiticus) growth and/or aflatoxins (AFs) production by visual agar plate assay and tip culture method. Most of the RAE bacteria strains (96 % strains) were determined to have decreased mycelia growth or AFs production levels by >50 % ( p < 0.05). Bacterial isolates were further characterized for chitinolytic activity and 22 strains (30 % strains) of identified RAE bacteria degraded colloidal chitin on the chitin medium plate. Ten selected chitinolytic RAE bacteria were tested for antifungal activity on peanuts and most of them significantly decreased mycelial growth and AFs production levels by >90 %. These results showed a wide distribution of biological control bacteria against AFs in Chinese peanut main producing areas and the selected RAE bacteria could potentially be utilized for the biocontrol of toxicogenic fungi. [ABSTRACT FROM AUTHOR]