The 'food leaving' behaviour score for for^s2 flies is low for flies raised in food-deprived conditions and high for flies raised in well-fed conditions. However, the increase in the score from FD to FED is greater for for^R than for^s or for^s2 flies.

The increase seen in metabolite content of adult heads in for^s2 flies raised on food-deprived versus well-fed conditions is greater than for^R flies in the case of carbohydrates, but less than for^R flies in the case of lipids.

In well-fed conditions, adult for^R flies have almost twice as much energy stored in whole-body lipid and about half the energy stored in carbohydrates compared to adult for^s or for^s2 flies.

for^s and for^s2 flies exhibit less food-related plasticity than for^R flies for a large majority of behavioural, metabolic and gene expression traits.

for^s2 flies exhibit a reduced sucrose responsiveness.

Fifteen minutes after a single conditioning cycle or a spaced (five conditioning cycles separated by 20-minute intervals) protocol, for^R homozygous mutants show stronger avoidance of the odor previously associated with shock than for^s or for^s2 homozygous mutants .

24 hours after a spaced (five conditioning cycles separated by 20-minute intervals) protocol, the for^R homozygous mutants show weaker memory of the association between an odor and shock than for^s or for^s2 homozygous mutants.

24 hours after a massed (five conditioning cycles immediately after one another) protocol, there is no difference between for^R, for^s and for^s2 homozygous mutants.

Learning performance of for^s2 homozygous mutants is indistinguishable from that of for^s homozygous mutants.

In the giant neuron culture system spontaneous nerve firing and supernumerary aftershock nerve spikes are evident after cessation of current injections in 42% of neurons. Phenotype is more extreme than for for^s. In voltage clamp studies, for^s2 neurons show significantly lower levels of both peak and sustained outward currents compared with for^R. This phenotype is also more extreme than for for^s. Half-activation voltages of the peak (but not sustained) K⁺ currents in for^s and for^s2 are shifted towards positive potentials compared with for^R. Slopes of voltage dependent activation are similar for the three alleles for both peak and sustained currents. Large amplitude (up to 5nA) spontaneous ejcs occur at high frequency, evoked ejcs that are time-locked to the stimulus show significantly greater amplitude. The number of ectopic nerve points in the muscles of for^s, for^s2 and for^lsR92 correlates with excitability levels of both central neurons and motor axons.

The olfactory response of homozygous for^R and homozygous for^s2 larvae to a food attractant is not significantly different. The number of homozygous for^s2 adult flies in an olfactory trap containing a food medium attractant after 48 hours is significantly greater than that of homozygous for^R adult flies. This increased olfactory trap response is also seen in hemizygous for^s2 adults. The increased olfactory trap response of for^s2 is recessive to the olfactory trap response of the for^R allele. The olfactory avoidance responses of for^R and for^s2 adult flies to propionic acid, ethyl acetate and acetone do not differ significantly.

for^R adults walk further from a recently ingested sucrose source than for^s2 flies. Csr³ does not increase walking distance in combination with either for allele.

In larval and adult tests, homozygotes show sitter-type behavior.

Homozygous or for^s2/for^s larvae have a "sitter" phenotype. for^s2/for^R larvae have a "rover" phenotype.