Most triatomine bugs (Hemiptera: Reduviidae: Triatominae) are hematophagous, though Belminus species can live off of cockroach hemolymph to complete their life cycle. In this work, we described the fixed action pattern (FAP) employed by B. ferroae to identify, approach, and suck on a living cockroach. The FAP described here is composed of the following stereotyped behaviors: (1) visual and/or olfactory detection of the cockroach, (2) reaching, (3) cautious approach, (4) antennal exploration, (5) extension of the proboscis, (6) piercing to sedate, (7) walking away and waiting (postsedation behavior), (8) second cautious approach, (9) extension of the proboscis, (10) piercing to suck hemolymph. The FAP sequence observed suggests that Belminus bugs are not predators like the rest of reduviids (assassin bugs)—but are kleptophagous ectoparasites, since they do not attack and kill a prey but rather steal hemolymph from its invertebrate host. Based on these ethological observations, we propose kleptophagy as a trait that naturally groups the Belminus species into the Triatominae subfamily. In order to identify chemicals cues that could elicit such FAP, we examined the behavior of B. corredori, B. ferroae, and B. herreri in response to the cockroaches’ odor, fresh cockroach feces and fresh rodent wastes. The last two sources were tested based on the assumption that abundant chemicals near host refuges could serve as cues for host orientation. We found that the cockroach odor emanating from a box significantly attracted B. corredori and B. herreri in a still air olfactometer. The three Belminus species approached the captive cockroach after 1 h, but avoided to climb the box. Odors emanating from the cockroach feces attracted B. corredori and B. ferroae in a Y-olfactometer. Triatomines and their hosts have intimately shared the same refuge for millions of years; certain molecules occur across invertebrate and vertebrate refuges and are recurrent in human abodes, thus plausibly explaining how these bugs can readily switch to the domestic habitat, while keeping with their kleptophagous nature.

尽管三倍体臭虫（Belminus）可以依靠蟑螂的淋巴淋巴来生存以完成其生命周期，但大多数三atomine臭虫（半翅目：Reduviidae：Triatominae）都具有食血性。在这项工作中，我们描述了固定双歧杆菌（B. ferroae）用来识别，接近和吮吸活蟑螂的固定动作模式（FAP）。这里描述的FAP由以下定型行为组成：（1）蟑螂的视觉和/或嗅觉检测；（2）到达；（3）谨慎的方法；（4）触角探查；（5）舌尖的伸展； （6）穿刺固定，（7）走开并等待（后发行为），（8）第二种谨慎方法，（9）长鼻延长，（10）穿刺以吸取血淋巴。观察到的FAP序列表明Belminus臭虫不像其他的毁灭性毒蛇（刺客臭虫）那样掠食动物，而是窃贼的外寄生虫，因为它们不会攻击并杀死猎物，而是从其无脊椎动物宿主中窃取血淋巴。根据这些行为学观察，我们建议将偷窃行为作为将Belminus物种自然地归入Triatominae亚科的一种特征。为了确定可能引发此类FAP的化学提示，我们检查了B. corredori，B。ferroae和B.herreri的行为。响应蟑螂的气味，新鲜的蟑螂粪便和新鲜的啮齿动物废物。在假设宿主避难所附近的大量化学物质可以作为宿主定向的线索的前提下，对最后两个来源进行了测试。我们发现，从一个盒子里散发出的蟑螂气味在静态空气嗅觉计中显着吸引了Corredori和B. herreri。1小时后，这三种Belminus物种接近了圈养的蟑螂，但避免爬上箱子。蟑螂粪便中散发出的气味吸引了B. corredori和B. ferroae在Y型嗅觉仪中 Triatomines及其寄主已经在数百万年的时间里同住一个避难所。某些分子在无脊椎动物和脊椎动物的避难所中出现，并在人类居所中反复出现，因此有可能解释了这些虫子如何易于转移到家庭栖息地，同时又保持其窃性。