Apparent Recall of Past Homing Locations by Microbembex monodonta Say (Hymenoptera: Crabronidae) — An Observation

Digger wasps Microbembex monodonta SAY (Hymenoptera, Crabronidae) rely exclusively on visual cues when pinpointing their nest entrances

“…In each shift-trial wasps eventually located their burrow. All responded similarly to the one shown in Fig 4A . Before attempting to dig for their burrows the wasps reacted by flying around the shifted configuration of local landmarks for two to three minutes, almost always where the configuration led them and their initial digging attempt was always at a location where, relative to the landmark array, they had found their burrow on their previous return (see [56]) for more evidence of this rapid location learning). Eventually the wasps corrected themselves and dug at their burrow entrances, which had not been disturbed; they did so by first hovering over the place they had been misled to dig, then flew directly above the actual burrow entrance, landed, and dug.…”

“…Tinbergen, for instance, found that the effectiveness of homing cues depends on aspects such as size, height, contrast with surroundings, color, texture, edges, shapes, patterns, surface area and even shadows [20]. Some investigators found the height of salient cues, which probably provided increased contrast against the sky, was primarily relevant for homing [7,10,14,19,21,22], while van Iersel and van den Assem [10] working with Bembix rostrata, using large flat rings, found surface area to be more important than height. Baerends [14] also believed that surface area of visual cues was an important property of landmarks used for homing.…”

“…In addition, introduced objects, both natural (e.g., pine cones) and man-made (e.g.,wooden cubes and flat rings), placed in the burrow vicinities of various digger wasp species, can be learned as cues for locating nest entrances. As with naturally-occurring local cues, wasps followed introduced cues when they were shifted and searched for their burrows relative to the shifted objects [ 6 , 7 , 10 , 17 , 20 , 22 , 26 , 40 in 41 ]. Cartwright and Collett [ 25 , 42 ] have shown that this search behaviour can be explained by assuming that insects memorize the view from the nest entrance (as if taking a snapshot) and upon returning to the nest area moving in such a way as to minimize the mismatch between what they currently see and their memorized snapshot.…”

“…She then leaves to collect provisions for her prospective larva. Returning to her burrow vicinity, she flies low, always facing forward (the direction of the burrow from the entrance) and without hesitation lands, digs precisely at the invisible burrow entrance, and enters [22,55].…”