Vision and genesis of survival strategies in tsetse flies: A laboratory study

Incorporating effects of age on energy dynamics predicts nonlinear maternal allocation patterns in iteroparous animals

“…The evidence for age-dependence in such traits is wide-ranging across systems, from a decrease in energetic costs with an improved lactation ability (e.g. seals [ 24 ]), an improved energy transfer efficiency (rats [ 75 ]), or reduced metabolic requirements post maturation (tsetse [ 58 , 59 , 62 ]), to an increase in energy intake with an improved mobility post maturation (tsetse [ 58 , 59 , 63 ]) or a decrease in energy intake later in life because of gut deterioration ( Drosophila [ 76 ]) or other physiological deteriorations. Such evidence could explain why these nonlinear patterns of maternal allocation are found across diverse taxonomic groups.…”

“…Linear or asymptotic age-dependent functions of energetic costs ( c t ), probability of successfully feeding ( q t ), energy gained per successful feeding attempt ( y t ) and environmentally driven mortality ( d t ). age dependence equation values rationale energetic costs c t increasing linearly c t = c 1 + c 2 × t c 1 = 2, 4 or 6 increasing difficulties in host searching and flying as damage accumulates [ 11 , 12 ] c 2 = 0.5, 1, 1.5, 2, 2.5 or 3 decreasing asymptotically c t = c 1 × (1.2 + e − c 2 × t ) c 1 = 1, 2, 3, 4, 5 or 6 no development costs of flight muscles, thoracic cuticle, or reproductive structures post maturity [ 58 , 59 , 62 ]; increased vision at maturity [ 63 ] improves host searching c 2 = 0.5 or 1 energy gained per successful feeding attempt y t increasing linearly y t = y 1 + y 2 × t y 1 = 6 energy transfer efficiency increases past first reproduction or digestion improves y 2 = 0.1, 0.2, 0.3, 0.4 or 0.5 increasing asymptotically y t = y 1 × (1 − e − y 2 × t ) y 1 = 6, 7, 8, 9, 10 or 11 fully developed gut at maturity with more volume for blood [ 39 …”

Big Baby, Little Mother: Tsetse Flies Are Exceptions to the Juvenile Small Size Principle

“…This means that the maximum life span must be much longer and, indeed, tsetse flies can survive in the field for about 6-8 months [36][37][38] thanks to adaptive behaviors to avoid predation, to tolerate temperature extremes, and to select safer resting sites. [39] By evolving a strategy where larvae do not need to feed, tsetse flies are able to reproduce in a variety of environmental conditions, and are not constrained by seasonal variability in rainfall or plant phenology. [40] Moreover, by feeding solely on host animals, tsetse flies have food available all year round, and are not limited by the cyclic absence of flowers and nectar.…”

“…This means that the maximum life span must be much longer and, indeed, tsetse flies can survive in the field for about 6–8 months [ 36–38 ] thanks to adaptive behaviors to avoid predation, to tolerate temperature extremes, and to select safer resting sites. [ 39 ]…”