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.

Haemolymph defence of an invasive herbivore: its breadth of effectiveness against predators

Abstract: Defensive characteristics of organisms affect the trophic linkages within food webs and influence the ability of invasive species to expand their range. Diabrotica v. virgifera is one such invasive herbivore whose predator community is restricted by a larval haemolymph defence. The effectiveness of this haemolymph defence against a range of predator functional and taxonomic guilds from the recipient biota was evaluated in a series of experiments. Eight predator species (Carabidae, Lycosidae, Formicidae) were fed D. v. virgifera 3rd instars or equivalent-sized maggots in the laboratory, and the mean times spent eating, cleaning their mouthparts, resting and walking following attacks on each prey were compared. Prey species were restrained in five Hungarian maize fields for 1 h periods beginning at 09:00 and 22:00 hours. The proportion of each species attacked and the number and identity of predators consuming each prey item were recorded. All predators spent less time eating D. v. virgifera larvae than maggots in the laboratory, and four of the eight predator species spent more time cleaning their mouthparts. The differential responses in the predator species indicate differences in susceptibility to the D. v. virgifera haemolymph defence. The predator communities (numerically dominated by Tetramorium caespitum) in the field showed clear diel patterns in their foraging behaviour, and D. v. virgifera was consumed by fewer predators than maggots. The defence of D. v. virgifera may partly explain how invasive insects that are exposed to an extensive predator community overcome biotic resistance to the invasion process.

Examining olfactory and visual cues governing host-specificity of a weed biological control candidate species to refine pre-release risk assessment

Abstract: In weed biological control programs, pre-release host-specificity testing relies traditionally on no-choice and choice feeding, oviposition, and development tests Rarely have they included detailed examination of behavioral responses to olfactory and visual cues of biological control candidates, although a better understanding of the mechanisms underlying host recognition may explain potential discrepancies between choice and no-choice tests, and/or between tests conducted in the lab versus field conditions We investigated how the seed-feeding weevil, Mogulones borraginis, distinguishes its host plant, Cynoglossum officinale, from three native confamilial non-target species in North America In behavioral bioassays, M borraginis responded to olfactory and visual cues individually and, to an even greater extent, to both plant cue modalities when offered simultaneously In tests with the combined cues, M borraginis was attracted to C officinale but responded with indifference or was repelled by non-target plants In electrophysiological experiments, we identified that M borraginis responded to ten volatile compounds and four wavelengths of lights from inflorescences of C officinale We propose that studies of responses to multimodal plant cues can advance our understanding of how biocontrol candidate species discriminate among host plants and closely related non-target species, thereby increasing the accuracy of environmental safety assessments pre-release

Characterisation of benzimidazole resistance of Cercospora beticola in Serbia using PCR-based detection of resistance-associated mutations of the β-tubulin gene

Abstract: A survey to detect and characterise benzimidazole resistance within populations of Cercospora beticola in Serbia was performed. From 52 field isolates collected from sugar beet and beet root, only eight were found to be benzimidazole-sensitive based on the inhibition of mycelial growth by discriminatory concentrations of carbendazim and thiophanate-methyl. Sensitivity tests revealed the presence of three resistant phenotypes among the tested isolates: high-resistance (HR), low-resistance (LR) and moderate-resistance (MR). The benzimidazole resistant isolates were characterised based on the DNA sequence of the β-tubulin gene and temperature sensitivity. The HR isolates showed no temperature sensitivity regardless of carbendazim concentration, whereas the LR and MR isolates were sensitive at lower temperatures. Analysis of the β-tubulin gene sequence revealed two amino acid replacements in the benzimidazole-resistant isolates of C. beticola. One was a glutamic acid to alanine change at position 198 (codon GAG to GCG) that was identified in HR isolates; this mutation has previously been reported to be associated with the development of benzimidazole resistance in C. beticola. The second replacement was a novel point mutation of phenylalanine (TTC) to tyrosine (TAC) at position 167, identified in low and moderate benzimidazole-resistant isolates, sharing a single LR/MR β-tubulin genotype. A diagnostic PCR-RFLP assay utilising a BsaI restriction site present in the benzimidazole sensitive and LR/MR genotypes but absent in the HR genotype was developed for the routine detection of high resistance. A mutation-specific PCR assay was developed for the diagnosis of LR/MR genotype based on a mutation from T to A at codon 167, which is unique to this genotype.