Self-initiated learning reveals memory performance and electrophysiological differences between younger, older and older adults with relative memory impairment.

Older adults display difficulties in encoding and retrieval of information, resulting in poorer memory. This may be due to an inability of older adults to engage elaborative encoding strategies during learning. This study examined behavioural and electrophysiological effects of explicit cues to self-initiate learning during encoding and subsequent recognition of words in younger adults (YA), older control adults (OA) and older adults with relative memory impairment (OD). The task was a variation of the old/new paradigm, some study items were preceded by a cue to learn the word (L) while others by a do not learn cue (X). Behaviourally, YA outperformed OA and OD on the recognition task, with no significant difference between OA and OD. Event-related potentials at encoding revealed enhanced early visual processing (70-140 ms) for L- versus X-words in young and old. Only YA exhibited a greater late posterior positivity (LPP; 200-500 ms) for all words during encoding perhaps reflecting superior encoding strategy. During recognition, only YA differentiated L- versus X-words with enhanced frontal P200 (150-250 ms) suggesting impaired early word selection for retrieval in older groups; however, OD had enhanced P200 activity compared to OA during L-word retrieval. The LPP (250-500 ms) was reduced in amplitude for L-words compared to both X- and new words. However, YA showed greater LPP amplitude for all words compared to OA. For older groups, we observed reduced left parietal hemispheric asymmetry apparent in YA during encoding and recognition, especially for OD. Findings are interpreted in the light of models of compensation and dedifferentiation associated with age-related changes in memory function.

Exposure to genetically engineered olive fly (Bactrocera oleae) has no negative impact on three non-target organisms.

Bactrocera oleae (Diptera: Tephritidae) remains a major pest of olive fruit production worldwide. Current pest management programs largely depend on chemical insecticides, resulting in high economic and environmental costs. Alternative pest control approaches are therefore highly desirable. We have created a conditional female-specific self-limiting strain of B. oleae (OX3097D-Bol) that could be applied for sustainable pest control. OX3097D-Bol olive fly carries a fluorescent marker (DsRed2) for identification and a self-limiting genetic trait that is repressed by tetracycline. In the absence of tetracycline, the tetracycline transactivator (tTAV) accumulates, resulting in female death at larvae and early pupal stages. The aim of this study was to evaluate the impact of genetically engineered OX3097D-Bol olive fly on three non-target organisms that either predate or parasitize olive flies, one from the guild of parasitoids (Psyttalia concolor) and two from the guild of predators (Pardosa spider species and the rove beetle Aleochara bilineata). No significant negative effect was observed on life history parameters, mortality and reproductive capacity of the non-target organisms studied. These results suggest that potential exposure to DsRed2 and tTAV gene products (e.g. mRNA and encoded proteins) would have a negligible impact on on-target organisms in the guilds or predators and parasitoids.

Insecticidal effects of deltamethrin in laboratory and field populations of Culicoides species: how effective are host-contact reduction methods in India?

BACKGROUND: Bluetongue virus (BTV) is transmitted by Culicoides biting midges and causes bluetongue (BT), a clinical disease observed primarily in sheep. BT has a detrimental effect on subsistence farmers in India, where hyperendemic outbreaks impact on smallholdings in the southern states of the country. In this study, we establish a reliable method for testing the toxic effects of deltamethrin on Culicoides and then compare deltamethrin with traditional control methods used by farmers in India. RESULTS: Effects of deltamethrin were initially tested using a colonised strain of Culicoides nubeculosus Meigen and a modified World Health Organisation exposure assay. This method was then applied to field populations of Culicoides spp. in India. The field population of C. oxystoma in India had a greater LC50 (0.012 ± 0.009%) for deltamethrin than laboratory-reared C.nubeculosus (0.0013 ± 0.0002%). Exposure of C. nubeculosus to deltamethrin at higher ambient temperatures resulted in greater rates of knockdown but a lower mortality rate at 24 h post-exposure. Behavioural assays with C. nubeculosus in WHO tubes provided evidence for contact irritancy and spatial repellence caused by deltamethrin. The field experiments in India, however, provided no evidence for repellent or toxic effects of deltamethrin. Traditional methods such as the application of neem oil and burning of neem leaves also provided no protection. CONCLUSIONS: Our study demonstrates that field-collected Culicoides in India are less susceptible to deltamethrin exposure than laboratory-bred C. nubeculosus and traditional methods of insect control do not provide protection to sheep. These low levels of susceptibility to deltamethrin have not been recorded before in field populations of Culicoides and suggest resistance to synthetic pyrethrioids. Alternative insect control methods, in addition to vaccination, may be needed to protect Indian livestock from BTV transmission.

A longitudinal investigation of the rejection-identification hypothesis.

The rejection-identification model (RIM; Branscombe, Schmitt, & Harvey, 1999) is supported by a number of previous studies (e.g., Schmitt, Branscombe, Kobrynowicz, & Owen, 2002; Schmitt, Spears, & Branscombe, 2003). This suggests that rejection by an outgroup can lead minority group members to identify more with their ingroup, thereby buffering them from the negative effects of discrimination. However, contradictory findings have been produced by other research (e.g., Eccleston & Major, 2006; Major, Quinton, & Schmader, 2003; McCoy & Major, 2003; Sellers & Shelton, 2003), suggesting that the relationship between rejection and identification is far from being completely understood. In the present study, we followed a cohort of 113 international students for a period of 2 years. The study sought to extend the previous work in two important ways. First, it examined the RIM within a longitudinal perspective. Second, building on important work on the multidimensionality of social identification (e.g., Ellemers, Kortekaas, & Ouwerkerk, 1999; Jackson, 2002), it tested the RIM using a three-dimensional approach to group identification. Results supported the predictions of the RIM and indicated that perceived discrimination causes minority group identification and not the reverse. The multidimensional approach also served to reveal a specific effect of discrimination on the cognitive components of identification.

The implicit identity effect: identity primes, group size, and helping.

Three studies consider the implicit bystander effect in the light of recent advances in social identity approaches to helping. Drawing on the social identity model of deindividuation effects we argue that the implicit bystander effect is shaped not by the number of others imagined, but by who those others are imagined to be. Studies 1 and 2 demonstrate that, when group membership is primed, increasing group size can facilitate helping in line with the norms and values of the group. Study 3 explores mediation processes in group level helping. As group size increases, female participants react faster to words associated with communalism when others are imagined as women rather than strangers. The paper demonstrates that group size and helping behaviour is qualified by an implicit identity effect.

The effects of control of resources on magnitudes of sex differences in human mate preferences.

We tested the hypothesis that magnitudes of sex differences in human mate preferences would be inversely related to control of resources. Specifically, we predicted that the ideal partner age, maximum and minimum partner ages tolerated and preferences for "physical attractiveness" over "good financial prospects" of female participants would approach parity with that of men with increasing control of resources. In a sample of 3770 participants recruited via an online survey, the magnitudes of sex differences in age preferences increased with resource control whereas the sex difference in preferences for "physical attractiveness" over "good financial prospects" disappeared when resource control was high. Results are inconsistent, and are discussed in the context of adaptive tradeoff and biosocial models of sex differences in human mate preferences.

Helping to improve the group stereotype: on the strategic dimension of prosocial behavior.

Three studies consider a basis for intergroup helping. Specifically, they show that group members may help others to disconfirm a stereotype of their own group as mean. Study 1 shows that Scots believe they are seen as mean by the English, resent this stereotype, are motivated to refute it, and believe out-group helping is a particularly effective way of doing so. Study 2 shows that increasing the salience of the English stereotype of the Scottish as mean leads Scots to accentuate the extent to which Scots are depicted as generous. Study 3 shows that increasing the salience of the stereotype of the Scots as mean results in an increase in the help volunteered to out-group members. These results highlight how strategic concerns may result in out-group helping. In turn, they underscore the point that helping others may be a means to advance a group's interest.