The minimum protein amount that Anastrepha obliqua MacQuart can detect in its alimentary source is variable, though the causes of such variation are not very well known. In this study, the authors tested whether the sexual partners nutritional condition and presence devoid of direct contact alter the A. obliqua protein discrimination threshold. Male and female insects were assigned to groups as follows: (i) newly emerged, (ii) deprived of protein source (yeast) during 18 days, (iii) non-yeast-deprived during 18 days, (iv) yeast-deprived in the presence of equally yeast-deprived sexual partners, (v) yeast-deprived in the presence of non-yeast-deprived partners, (vi) non-yeast-deprived with yeast-deprived partners and (vii) non-yeast-deprived with non-yeast-deprived partners. The sexual partners were maintained apart by a transparent plastic screen with small holes. Not only the males presence but also their nutritional condition have altered the females discrimination threshold, particularly when the females were deprived and when non- deprived females cohabited with deprived males. Therefore, the females threshold was determined by their own nutritional condition in addition to recognition of the males nutritional condition. The males discrimination threshold was higher for non-deprived subjects than for the deprived ones. The occurrence of responses in the absence of direct contact between males and females has shown that they may use a chemical mechanism for mutual recognition of the sexual partner nutritional condition.
Diet selection; fruit fly; feeding behavior
