Effect of diet and density on larval immune response and larval and adult host-preference in Spodoptera littoralis

Polyphagy presents difficulties to an insect, especially in terms of host choice. The adult insect must choose from a large number of possible host plant species, something which is considered to require extensive neural capacity to process. In order to decrease the amount of information to process, it has been suggested that polyphagous insects could rely on previous larval experience to make a choice. In the polyphagous noctuid moth Spodoptera littoralis it has frequently been found that female oviposition choice is driven by ‘larval memory’, indicating that the adult chooses to oviposit upon the same host upon which it fed as a larva. However, is there a larval density effect on how the host plant is perceived, and does this effect adult behaviour? In this study the insects were reared in three different treatments: low-density (optimal), highdensity and starvation (both assumed suboptimal), on three different diets (cotton, cabbage, and maize). A development study was carried out whereby it was indeed found that lowdensity was optimal, in terms of fitness (pupal weight) and fecundity (egg load). High-density larvae were found have a higher investment in immune response, which coupled with the reduction in pupal weight and egg load, indicates that high larval density may cause a reallocation of energy and a negative effect on fitness and fecundity. Starvation was highly detrimental, having a high development time and death rate. It was found that larval density did not have an effect on larval host choice, however, it was clear that the larvae were making an experience-based choice, irrespective of density. Adult oviposition choice, however, displayed a switch from choice in adults deriving from lowdensity treatments to the supposedly random laying seen in the adults originating from the high-density treatment. Furthermore, first choice in oviposition host showed a switch between low- and high-density reared insects, with high-density adults laying eggs on a nonexperienced plant first

Visuo-motor attention during object interaction in children with developmental coordination disorder

Developmental coordination disorder (DCD) describes a condition of poor motor performance in the absence of intellectual impairment. Despite being one of the most prevalent developmental disorders, little is known about how fundamental visuomotor processes might function in this group. One prevalent idea is children with DCD interact with their environment in a less predictive fashion than typically developing children. A metric of prediction which has not been examined in this group is the degree to which the hands and eyes are coordinated when performing manual tasks. To this end, we examined hand and eye movements during an object lifting task in a group of children with DCD (n = 19) and an age-matched group of children without DCD (n = 39). We observed no differences between the groups in terms of how well they coordinated their hands and eyes when lifting objects, nor in terms of the degree by which the eye led the hand. We thus find no evidence to support the proposition that children with DCD coordinate their hands and eyes in a non-predictive fashion. In a follow-up exploratory analysis we did, however, note differences in fundamental patterns of eye movements between the groups, with children in the DCD group showing some evidence of atypical visual sampling strategies and gaze anchoring behaviours during the task

The importance of coordinated eye movements and steering for driving performance

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