CABI

About: CABI is a nonprofit organization based out in Wallingford, United Kingdom. It is known for research contribution in the topics: Population & Introduced species. The organization has 789 authors who have published 1759 publications receiving 73843 citations. The organization is also known as: Centre for Biosciences and Agriculture International.

Molecular analysis of the major Phytophthora species on cocoa

Abstract: The internally transcribed spacer (ITS) regions of the ribosomal RNA (rRNA) gene cluster of 161 isolates of Phytophthora species involved in pod rot, stem canker and leaf blight of cocoa were analysed to determine inter- and intraspecific variation in this disease complex. The species P. palmivora , P. megakarya , P. capsici , P. citrophthora and P. nicotianae could all be clearly distinguished by PCR amplification of the ITS region followed by restriction analysis with Hae III, Hinf I, Pvu II and Alu I. This method provided a relatively rapid identification procedure for these species, and was able to distinguish isolates that had previously been misidentified by morphological methods. Sequence analysis showed that the four main cocoa-associated species formed two distinct groups, one comprising P. capsici and P. citrophthora , and the other P. palmivora and P. megakarya . Detailed sequence analysis and comparison with published literature suggested that P. capsici isolates from cocoa may be closely related to P. tropicalis , a species recently described from Cyclamen and Dianthus .

Comparative assessment of the efficacy of entomopathogenic nematode species at reducing western corn rootworm larvae and root damage in maize.

Abstract: The western corn rootworm (Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) is an invasive maize (Zea mays L.) pest in Europe. Crop yield is significantly impacted by the feeding of all three larval instars on maize roots, making them prime targets for control measures. Therefore, the control efficacy of three entomopathogenic nematodes (EPNs), Steinernema feltiae (Filipjev), Heterorhabditis bacteriophora Poinar, and H. megidis Poinar, Jackson and Klein (Nematoda: Rhabditida), was studied in four field plot experiments in southern Hungary in 2005 and 2006. All EPN species significantly reduced D. v. virgifera independently, whether applied as a row spray with a solid stream into the soil at sowing or onto the soil along maize rows in June. When applied at maize sowing, H. bacteriophora was more effective at reducing D. v. virgifera (81%) than H. megidis (49%) and S. feltiae (36%). When applied in June, H. bacteriophora and H. megidis were more effective at reducing D. v. virgifera (around 70%) than S. feltiae (32%). All tested EPN species significantly reduced damage on maize roots independently, whether they were applied at sowing or in June. Damage, however, was not totally prevented. The use of H. bacteriophora for the development of a biological control product for inundative releases against D. v. virgifera larvae is suggested.

Comparison of water, oils and emulsifiable adjuvant oils as formulating agents for Metarhizium anisopliae for use in control of Boophilus microplus.

Abstract: Studies were conducted to identify oil-based formulating agents (paraffinic oil, palm oil and emulsifiable adjuvant oils (EAOs)) for Metarhizium anisopliae that were superior to water with simple surfactants using a germination test and a bioassay against Boophilus microplus. Germination of conidia in all formulations, except 10% coconut EAO, produced more than 68% germination at 24 h and nearly 100% at 48 h. Coconut oil (average survival time (AST)=4.6±0.28 days) and 10% liquid paraffin EAO (AST=4.4±0.15 days) enhanced the pathogenicity of M. anisopliae to B. microplus relative to water (AST=8.4±0.42 days). M. anisopliae in 10% liquid paraffin EAO was the most effective formulation having a moderately high germination after 24 h and a low AST as well as a high AST in the control. In the second experiment, germination of conidia in 2% liquid paraffin EAO and 2% Cropspray was higher than in 2% Codacide oil at 24 h, however, all treatments reached 100% germination after 48 h. The ASTs of the EAO based M. anisopliae formulations (Average AST=6.4±0.54 days) were similar but lower that the ASTs of the controls (Average AST=9.6±0.28 days).

Diversity and abundance of insect herbivores foraging on seedlings in a rainforest in Guyana

Abstract: Summary 1. Free-living insect herbivores foraging on 10 000 tagged seedlings representing five species of common rainforest trees were surveyed monthly for more than 1 year in an unlogged forest plot of 1 km2 in Guyana. 2. Overall, 9056 insect specimens were collected. Most were sap-sucking insects, which represented at least 244 species belonging to 25 families. Leaf-chewing insects included at least 101 species belonging to 16 families. Herbivore densities were among the lowest densities reported in tropical rainforests to date: 2.4 individuals per square metre of foliage. 3. Insect host specificity was assessed by calculating Lloyd’s index of patchiness from distributional records and considering feeding records in captivity and in situ. Generalists represented 84 and 78% of sap-sucking species and individuals, and 75 and 42% of leaf-chewing species and individuals. In particular, several species of polyphagous xylem-feeding Cicadellinae were strikingly abundant on all hosts. 4. The high incidence of generalist insects suggests that the Janzen–Connell model, explaining rates of attack on seedlings as a density-dependent process resulting from contagion of specialist insects from parent trees, is unlikely to be valid in this study system. 5. Given the rarity of flushing events for the seedlings during the study period, the low insect densities, and the high proportion of generalists, the data also suggest that seedlings may represent a poor resource for free-living insect herbivores in rainforests.