Larval Cannibalism and Pupal Defense Against Cannibalism in Two Species of Tenebrionid Beetles

Self Cite

Exarate pupae of the beetle Zophobas atratus Fab. (Coleoptera: Tenebrionidae) have free appendages (antenna, palp, leg, and elytron) that are highly sensitive to mechanical stimulation. A weak tactile stimulus applied to any appendage initiated a rapid rotation of abdominal segments. High-speed photography revealed that one cycle of defensive abdominal rotation was induced in an all-or-none fashion by bending single or multiple mechanosensory hairs on a leg or prodding the cuticular surface of appendages containing campaniform sensilla. The direction of the abdominal rotation completely depended on the side of stimulation; stimulation of a right appendage induced a right-handed rotation about the anterior-posterior axis of the pupal body and vice versa. The trajectories of the abdominal rotations had an ellipsoidal or pear-shaped pattern. Among the trajectory patterns of the rotations induced by stimulating different appendages, there were occasional significant differences in the horizontal (right-left) component of abdominal rotational movements. Simultaneous stimulation of right and left appendages often induced variable and complex patterns of abdominal movements, suggesting an interaction between sensory signals from different sides. When an abdominal rotation was induced in a freely lying pupa, the rotation usually made the pupa move away from or turn its dorsum toward the source of stimulation with the aid of the caudal processes (urogomphi), which served as a fulcrum for transmitting the power of the abdominal rotation to the movement or turning of the whole body. Pattern generation mechanisms for the abdominal rotation were discussed.

Section: Introductionmentioning

confidence: 99%

Defensive Abdominal Rotation Patterns of Tenebrionid Beetle,Zophobas atratus, Pupae

Ichikawa

Nakamura

Yamawaki

2012

Self Cite

“…These features of the pupal response suggest that the sequential abdominal movements may represent a desperate attempt at resisting repeated attacks from a large predator. The potential predators may include cannibalistic larvae of Z. atratus (Ichikawa and Kurauchi 2009). …”

Section: Discussionmentioning

confidence: 99%

“…The pupae of T. molitor exhibit another type of defensive response: a rapid circular rotation of the abdomen, fringed with many spines, against tactile stimulation of their free appendages (Hollis 1963; Askew and Kurtz 1974). This response may be effective in protecting the pupae from larval cannibalism (Ichikawa and Kurauchi 2009). …”

Section: Introductionmentioning

confidence: 99%

A Third Type of Defensive Behavior in the Tenebrionid BeetleZophobas atratusPupae

Ichikawa

Sakamoto

2013

Self Cite

Pupae of the tenebrionid beetle Zophobas atratus Fabricius (Coleoptera: Tenebrionidae) exhibit two types of reflex abdominal motions in response to tactile stimulation: circular rotation and lateral bending to close pinching devices (gin-traps). In the present study, the pupa exhibited novel, sequential abdominal movements at 0.3–2.2 sec after the onset of mechanical stimulation. The most effective stimulation was gentle, double brushing on the ventral surface of an abdominal segment (sternite). The sequential abdominal movements consisted of the following three types of discrete elementary motions (100–350 ms in duration): rapid vibration of 30–40 Hz, circular rotation (or swing), and small wiggling movements. A sequence of abdominal movements generally started with a few bouts of vibration, but the number and order of subsequent motions varied considerably among different sessions and conditions. A restrained pupa often showed a prolonged sequence of many motions, including several rotations, whereas an unrestrained pupa often shortened the sequence by skipping a few rotations after the displacement of its whole body induced by the first abdominal rotation. Stimulation of two types of mechanosensitive sensilla, the hair sensilla (touch sensors) and campaniform sensilla (strain sensors), seemed to be necessary to initiate the defensive response. In natural environments, crawling of a small predator (or parasitoid) on the surface of the abdomen or repeated attacks of a large predator may induce this defensive response in the pupae.

“…For example, pupae of some tenebrionid species rotate their abdominal segments upon tactile stimulation to effectively deter predation and cannibalism (Ichikawa and Kurauchi 2009). Pupae of certain coccinellid species possess “gin traps” that can be employed to sever the antennae of potential predators such as ants (Eisner and Eisner 1992).…”

Section: Discussionmentioning

confidence: 99%

DoesTribolium brevicornisCuticular Chemistry Deter Cannibalism and Predation of Pupae?

Alabi

Dean

Michaud

et al. 2011

The cuticular hydrocarbons of insects are species-specific and often function as semiochemicals. The activity of Tribolium brevicornis cuticular hydrocarbons as feeding deterrents that ostensibly function to prevent pupal cannibalism and predation was evaluated. The cuticular hydrocarbons of T. brevicornis pupae were characterized and flour disk bioassays conducted with individual and combined extract components incorporated into artificial diets on which Tribolium adults fed for six days. Feeding by T. brevicornis and T. castaneum on flour disks containing cuticular extracts of T. brevicornis pupae resulted in reduced consumption and weight loss relative to feeding on control flour disks. In both cases, feeding deterrence indices exceeded 80% suggesting that T. brevicornis cuticular hydrocarbons could function to deter cannibalism and predation of pupae by larvae and adult beetles. Sixteen different cuticular hydrocarbons were identified in T. brevicornis pupal extracts. Eight of the commercially available linear alkanes were tested individually in feeding trials with eight Tribolium species. One compound (C28) significantly reduced the amount of food consumed by three species compared to control disks, whereas the compounds C25, C26, and C27 elicited increased feeding in some species. Four other compounds had no effect on consumption for any species. When four hydrocarbon mixtures were tested for synergistic deterrence on T. brevicornis and T. castaneum, none significantly influenced consumption. Our results indicate that the cuticular chemistry of T. brevicornis pupae could serve to deter predation by conspecific and congeneric beetles.