Provisioning call by mothers of a subsocial shield bug

Chordotonal organs in hemipteran insects: unique peripheral structures but conserved central organization revealed by comparative neuroanatomy

Hemipteran insects use sophisticated vibrational communications by striking body appendages on the substrate or by oscillating the abdominal tymbal. There has been, however, little investigation of sensory channels for processing vibrational signals. Using sensory nerve stainings and low invasive confocal analyses, we demonstrate the comprehensive neuronal mapping of putative vibration-responsive chordotonal organs (COs) in stink bugs (Pentatomidae and Cydinidae) and cicadas (Cicadidae). The femoral CO (FCO) in stink bugs consists of ventral and dorsal scoloparia, homologous to distal and proximal scoloparia in locusts, which are implicated in joint movement detection and vibration detection, respectively. The ligament of the dorsal scoloparium is distally attached to the accessory extensor muscle, whereas that of the ventral scoloparium is attached to a specialized tendon. Their afferents project to the dorso-lateral neuropil and the central region of the medial ventral association center (mVAC) in the ipsilateral neuromere, where presumed dorsal scoloparium afferents and subgenual organ afferents are largely intermingled. In contrast, FCOs in cicadas have decreased dorsal scoloparium neurons and lack projections to the mVAC. The tymbal CO of stink bugs contains four sensory neurons that are distally attached to fat body cells via a ligament. Their axons project intersegmentally to the dorsal region of mVACs in all neuromeres. Together with comparisons of COs in different insect groups, the results suggest that hemipteran COs have undergone structural modification for achieving faster signaling of resonating peripheral tissues. The conserved projection patterns of COs suggest functional importance of the FCO and subgenual organ for vibrational communications.

Altruism during predation in an assassin bug

Zelus annulosus is an assassin bug species mostly noted on Hirtella physophora, a myrmecophyte specifically associated with the ant Allomerus decemarticulatus known to build traps on host tree twigs to ambush insect preys. The Z. annulosus females lay egg clutches protected by a sticky substance. To avoid being trapped, the first three instars of nymphs remain grouped in a clutch beneath the leaves on which they hatched, yet from time to time, they climb onto the upper side to group ambush preys. Long-distance prey detection permits these bugs to capture flying or jumping insects that alight on their leaves. Like some other Zelus species, the sticky substance of the sundew setae on their forelegs aids in prey capture. Group ambushing permits early instars to capture insects that they then share or not depending on prey size and the hunger of the successful nymphs. Fourth and fifth instars, with greater needs, rather ambush solitarily on different host tree leaves, but attract siblings to share large preys. Communal feeding permits faster prey consumption, enabling small nymphs to return sooner to the shelter of their leaves. By improving the regularity of feeding for each nymph, it likely regulates nymphal development, synchronizing molting and subsequently limiting cannibalism.