Improving the Lifetime Efficiency of Trimedlure-Dispensing System in Trapping the Fruit Fly Ceratitis capitata Using Polyethylene Matrix.

Detection of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is highly reliant on traps loaded with trimedlure (TML), a male-specific attractant. The successful application of attractants requires that constituents are placed in a suitable dispensing system to reduce volatilization and increase the effective field longevity of the attractant. A series of trials were conducted in different fruit orchards to test 1) the efficiency of a polyethylene-matrix plug in regulating the emission rate of TML 2) and the lifetime attractiveness of the plug compared to the cotton wick dispenser. Cotton dispensers containing the recommended dose of TML (0.75 cm3) and with a double dose (1.5 cm3) remained active for 6 and 8 wk, respectively. The increase in TML dose from 0.75 cm3 to 1.5 cm3 led to an increase in the longevity of the cotton dispenser, but there was no significant difference between the doses in biological activity. In all trials, TML-polyethylene matrix dispensers were more efficient under field conditions as they attracted more males for up to 12 wk and prolonged the release of TML more than the cotton wick dispensers. The TML-loaded polyethylene matrix dispensers might be useful in 1) minimizing the losses of the liquid TML from cotton wicks, 2) avoiding the damage that occurs when using other dispensers, 3) prolonging the TML lifetime in the field through regulating its release rates, 4) potentially minimizing the adverse effect of high temperatures on release rate, and, finally, 5) minimizing the costs of using large amounts of expensive TML solutions.

Limb Regeneration and Interference Competition Consequences on Foraging Efficiency of Coccinella undecimpunctata and Hippodamia variegata (Coccinellidae: Coleoptera) to Their Prey, Aphis craccivora (Hemiptera: Aphididae).

Regeneration of limbs lost during development has been recorded in a large number of species of hexapoda including many Coccinellids. Although regeneration has obvious survival and fitness benefits, it has also been demonstrated to impose costs on development, reproduction, and behavior. To investigate consequences of regeneration on foraging behavior, Coccinella undecimpunctata L. and Hippodamia variegata (Goeze) larvae were treated to remove one limb, allowed to pupate and regenerate and then prey searching ability assessed. Different densities of adults were placed in Petri dishes with aphid prey and consumption assessed over a 24-h period. Amputation/regeneration, predator species, and predator density significantly affected the total number of aphids consumed. Aphid consumption rates and predation efficiency of both regenerated and control beetles significantly increased as predator density increased. Although there were significant differences in consumption between ablated/regenerated and control C. undecimpunctata at each predator densities, H. variegata did not. Further, mutual interference was significantly higher for regenerated compared with control C. undecimpunctata but not so for H. variegata. This is the first demonstration of an effect of ablation/regeneration on foraging behavior of C. undecimpunctata and suggests that H. variegata demonstrates an adaptive phenotypic response to limb regeneration. Coccinellids are widely used as biological agents and these findings concerning the impact of variation in predator density have clear implications for the management of predator-prey ratios in order to maximize efficiency of pest consumption.

Screening for common copy-number variants in cancer genes.

For most cases of colorectal cancer that arise without a family history of the disease, it is proposed that an appreciable heritable component of predisposition is the result of contributions from many loci. Although progress has been made in identifying single nucleotide variants associated with colorectal cancer risk, the involvement of low-penetrance copy number variants is relatively unexplored. We have used multiplex amplifiable probe hybridization (MAPH) in a fourfold multiplex (QuadMAPH), positioned at an average resolution of one probe per 2 kb, to screen a total of 1.56 Mb of genomic DNA for copy number variants around the genes APC, AXIN1, BRCA1, BRCA2, CTNNB1, HRAS, MLH1, MSH2, and TP53. Two deletion events were detected, one upstream of MLH1 in a control individual and the other in APC in a colorectal cancer patient, but these do not seem to correspond to copy number polymorphisms with measurably high population frequencies. In summary, by means of our QuadMAPH assay, copy number measurement data were of sufficient resolution and accuracy to detect any copy number variants with high probability. However, this study has demonstrated a very low incidence of deletion and duplication variants within intronic and flanking regions of these nine genes, in both control individuals and colorectal cancer patients.

Intergenomic arms races: detection of a nuclear rescue gene of male-killing in a ladybird.

Many species of arthropod are infected by deleterious inherited micro-organisms. Typically these micro-organisms are inherited maternally. Consequently, some, particularly bacteria of the genus Wolbachia, employ a variety of strategies that favour female over male hosts. These strategies include feminisation, induction of parthenogenesis and male-killing. These strategies result in female biased sex ratios in host populations, which lead to selection for host factors that promote male production. In addition, the intra-genomic conflict produced by the difference in transmission of these cytoplasmic endosymbionts and nuclear factors will impose a pressure favouring nuclear factors that suppress the effects of the symbiont. During investigations of the diversity of male-killing bacteria in ladybirds (Coccinellidae), unexpected patterns of vertical transmission of a newly discovered male-killing taxon were observed in the ladybird Cheilomenes sexmaculata. Initial analysis suggested that the expression of the bacterial male-killing trait varies according to the male(s) a female has mated with. By swapping males between females, a male influence on the expression of the male-killing trait was confirmed. Experiments were then performed to determine the nature of the interaction. These studies showed that a single dominant allele, which rescues male progeny of infected females from the pathological effect of the male-killer, exists in this species. The gene shows typical Mendelian autosomal inheritance and is expressed irrespective of the parent from which it is inherited. Presence of the rescue gene in either parent does not significantly affect the inheritance of the symbiont. We conclude that C. sexmaculata is host to a male-killing gamma-proteobacterium. Further, this beetle is polymorphic for a nuclear gene, the dominant allele of which rescues infected males from the pathogenic effects of the male-killing agent. These findings represent the first reported case of a nuclear suppressor of male-killing in a ladybird. They are considered in regard to sex ratio and intra-genomic conflict theories, and models of the evolutionary dynamics and distribution of inherited symbionts.