Abstract: Life history parameters and fitness of tephritid flies are closely linked to diet. Studies of locomotor behaviour can provide insights to these links, but little is known about how locomotor behaviour is influenced by diet. In the present study, video recordings of Queensland fruit flies Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) (‘Q-flies’) maintained individually in cages are used to determine how diet affects activity patterns (flight, walking, grooming, inactivity) of males and females at ages ranging from 4 to 30 days. Frequency and total duration of activities over 10 min trials were affected by diet, age and sex. Supplementation of diet with hydrolysed yeast resulted in higher frequency and duration of flight in flies of all ages and both sexes. The effect of diet on other activities varied with age. Q-flies fed sugar only increased walking frequency steadily from 4 to 30 days post-eclosion, while flies fed sugar + yeast walked more often at 4 and 10 days but then exhibited a sharp decline at 30 days post-eclosion. Levels of inactivity remained consistent in flies fed sugar + yeast, whereas flies fed sugar only exhibited a marked increase in inactivity from 4 to 30 days post-eclosion. Compared to older flies, 4 day-old Q-flies fed sugar only spent considerably more time grooming. We discuss the potential of activity monitoring as a quality control test for flies that are mass-reared for use in Sterile Insect Technique programs.
Abstract: Burst speed, a common metric of locomotor performance, is typically measured on horizontal surfaces.
Studies of locomotor performance in spiders have examined vertical and horizontal locomotion, but not
the effects of intermediate inclines. We measured the effect of angle of incline, body size, relative leg
length (variation not explained by body size) and relative body mass (variation not explained by body
size or leg length, often interpreted as ‘condition’) on maximum running speed in two Australian spiders
differing in habitat architecture and foraging strategy. Males of a ground-dwelling jumping spider,
Jacksonoides queenslandica, and an orb-web spider, Nephila plumipes, were forced to run on raceways
inclined at þ0, þ30 and þ60. At the population level, maximum running speed decreased on inclined
compared to level raceways for both species, but the effects of slope varied substantially between
individuals. While speed was not influenced by body size or relative mass in either species, it was
influenced by leg length in both. In J. queenslandica, relative leg length did not influence horizontal
running speed but was positively related to speed on slopes, principally because relatively short-legged
spiders were slowed whereas relatively long-legged spiders were not affected. In N. plumipes relative leg
length was related negatively to running speed on horizontal surfaces but positively to running speed on
slopes. Unlike J. queenslandica, N. plumipes was little affected by slopes of 30 but slowed markedly on
slopes of 60, irrespective of relative leg length.We suggest that performance advantages on inclines may
promote relatively longer legs.
Abstract: Both genders of spiders compete for a variety of resources. They typically use non-contact display, followed by increasingly escalated contact phases comprising touching and sparring and then escalated grappling and biting. Studies of spiders have been central to the understanding of assessment strategies and, for the most part, the data support self-assessment rather than mutual-assessment models. There is good evidence for effects of resource value and ownership on the conduct and outcome of these contests. Fights may have short-term consequences with respect to fatigue, but can have longer-term consequences such as loss of aoppendages or death. Specific experience of winning or losing contests may also influence future encounters. Spiders have also been used in studies of the underlying genetic basis for variation in contest behaviour. Spiders have been the inspiration for motivational models of aggression and we propose a new two-dimensional model that uses cost and resource value as the major factors influencing motivational state and hence choice and duration of activities.
