Results
Within each food treatment, the growth rate of colonies during resource
pulses (λp ) was higher than the growth rate
off-pulse (ambient resources only, λ0) (paired t-test of
growth rate for each colony in pulse and ambient periods: t = 10.77, df
= 26, p = < 0.001; Fig 2). Growth rates during pulses did not
differ significantly between early-pulse and late-pulse treatments (Wald
χ2 1 = 1.59 P = 0.208)
(Fig 2); in both, colonies doubled in weight every ~10
days. However, early-pulse colonies grew at a significantly faster rate
during the off-pulse period when compared to late-pulse colonies (Wald
χ2 1= 5.42, P = 0.020)
(Fig 2). Late-pulse and early-pulse colonies switched from growth to
decline after ~40 days in the field (Early:\(\overset{\overline{}}{\tau}\) = 43.2 days (CI95%[38.8, 47.6], Late: \(\overset{\overline{}}{\tau}\) = 42.8 days
(CI95% [38.3, 47.2]) (Wald
χ2 1 = 0.02, P = 0.89).
The faster growth rate, especially during the off pulse period led to
significantly higher peak weights of early-pulse colonies
(\(\overset{\overline{}}{W_{T}}\) = 158.4 g; CI95%[108.7, 231.2]) than of late-pulse colonies
(\(\overset{\overline{}}{W_{T}}\) = 97.4 g; CI95%[66.8, 142.1]) (Wald χ2 = 4.55, P =
0.033) (Fig 3).
Half of early-pulse colonies (7/14) produced new queens, while only 2 of
14 late-pulse colonies did so. The number of new queens produced also
was significantly greater for early-pulse colonies (Ῡ = 6.14,
CI95% [2.23, 26.87]) than for late-pulse colonies
(Ῡ = 0.21; CI95% [0.01, 7.20]) (Wald
χ2 = 30.38, P<0.001).