Habitat avoidance is an anti-parasite behaviour exhibited by at-risk hosts that can minimize exposure to parasites. Because environments are often heterogeneous, host decision-making with regards to habitat use may be affected by the presence of parasites and habitat quality simultaneously. In this study we examine how the ovipositing behaviour of a cactiphilic fruit fly, Drosophila nigrospiracula, is affected by the presence of an ectoparasitic mite, Macrocheles subbadius, in conjunction with other environmental factors – specifically the presence or absence of conspecific eggs and host plant tissue. We hypothesized that the trade-off between site quality and parasite avoidance should favour ovipositing at mite-free sites even if it is of inferior quality. We found that although flies avoided mites in homogeneous environments (86% of eggs at mite-free sites), site quality overwhelmed mite avoidance. Both conspecific eggs (65% of eggs at infested sites with other Drosophila eggs) and host plant tissue (78% of eggs at infested sites with cactus) overpowered mite avoidance. Our results elucidate the context-dependent decision-making of hosts in response to the presence of parasites in variable environments, and suggest how the ecology of fear and associated trade-offs may influence the relative investment in anti-parasite behaviour in susceptible hosts.

In the Ecuadorian cloud forest, males of the parasitoid braconid wasp Napo townsendi Shaw displayed facultative lekking, appearing both singly and in groups of 2–7 on the leaf tops of various plant species. To attract females, they constantly employed a stereotypical, spread-winged calling behaviour, apparently releasing a sex pheromone combed from the lateral metasomal exocrine glands and applied to the wings and hind legs. Aggregated males used the same posture in conspecific agonistic displays, often leading to physical fighting. While female wasps were attracted to and mated with displaying singletons, they also made a choice among aggregated males. When females approached, males vibrated their wings in a brief courtship and mounted. Details of copulation behaviour, which lasted on an average of 3–4 min, are described. Without apparent physical weaponry, the displaying wasps successfully warded off attacks from an assortment of predatory arthropods, particularly salticid spiders. We present case studies of repeated unsuccessful predation attempts by salticids. Here, we postulate that calling and release of sex pheromone may double as both an intrasexual agonistic display and an aposematic advisory to predators that the wasps employ a chemical defence.

In France, during the summer, cattle in mountainous pastures can be highly exposed to tabanid bites. The persistent biting behaviour of tabanids not only causes disturbance, but is also responsible for transmitting diseases, such as bovine besnoitiosis. The purpose of this study was to better identify the level of tabanid annoyance on cattle by means of insect trapping and direct observation of cows. Tabanids were active during the entire daily observation period (10:00–16:00), except for Haematopota sp., which were less active in the morning. The tabanids collected in Nzi traps were generally representative of those that landed on cattle, except for Haematopota sp., as Nzi traps were not very effective for these species. The preferred feeding sites for most species appeared to be cow's legs or udder. Leg stamping was the defensive reaction most related to a tabanid alighting on a host. Generalized linear mixed models showed that the parameters associated with tabanid landings on hosts were related to weather and altitude, but not to landscape structure. Increased landings were mostly associated with the higher temperatures and lower wind speeds at midday, but some differences were observed between species. The results indicate that cattle-protection measures should be taken during the peak of tabanid abundance when climatic conditions favour intense biting activity. Nzi traps set close to livestock were very effective to catch tabanids and could help in reducing the annoyance caused by horse flies.

Most praying mantids possess a single tympanal ear located in the ventral midline between the metathoracic legs. The auditory system is generally most sensitive to ultrasound in the 25–50 kHz range. Flying males exhibit a short-latency, stereotyped, multi-component response to ultrasound that allows them to escape from attacking bats. This study describes a small subset of species that differs in three major respects from the majority of mantis species: (1) their auditory tuning is 1.5–2 times broader; (2) they are sensitive to frequencies above 60 kHz (up to 130 kHz in some species) with thresholds as low or lower than at 25–50 kHz; (3) the behavioural response of the broadly tuned (BT) species includes 10–50 times more flight cessations and can be far less stereotyped, i.e. more ‘evitable’, than that of narrowly tuned (NT) species. However, BT species do not differ from NT species in overall sensitivity. Two species from one subfamily, the Amelinae (family Mantidae), stand out because they are among the least sensitive of any hearing mantids so far tested. Although the two amelines differ from one another in tuning curve shape, they are both more broadly tuned than most mantids. The occurrence of BT species does not follow any obvious phylogenetic pattern; they are patchily distributed among the mantis families, and both BT and NT species can be found in the same subfamily or tribe. We suggest that BT species are responding to a shared ecological pressure. Based on their tuning, the nature of their behavioural response, and their geographic distribution, we hypothesize that high duty cycle (HDC) bats (Rhinolophidae and Hipposideridae) pose a special danger to BT mantids in addition to the threat that all flying mantids face from the more common and widely distributed low duty cycle (LDC) bats.

This study examines the behavioural responses to ultrasound in 52 species from the family Cicindelidae using both tethered flight and non-flight assays. Tethered flying tiger beetles respond to trains of bat-like ultrasonic pulses with a short-latency, multi-component behaviour. There was no variation in the nature of the behavioural responses regardless of geographical distribution or phylogenetic position. Lowest mean behavioural thresholds lie predominantly between 30 and 45 kHz. Sensitivity, however, varies widely, and several species do not respond at all in these assays. The lowest thresholds for responders are most often between 70 and 80 dB SPL. Almost all subgenera of North American tiger beetles in the genus Cicindela have at least some species with low-threshold acoustic behaviour. The single exception is the large subgenus Cicindela where all species are completely unresponsive or have very high thresholds. There was little relationship between habitat and responsiveness to ultrasound, but there is a strong correlation with seasonal activity – species with adults active in the spring and autumn (all in the subgenus Cicindela) do not show ultrasound-triggered behaviour whereas summer-active species generally do. Superimposing these data on a current phylogeny of the North American tiger beetles suggests that acoustic behaviour (and hearing) is a shared primitive trait among the taxa examined here and that there have been at least five independent losses of this character.

Head triangulation is a regular component of the defensive behaviour of both Heterodon and Dasypeltis. In Heterodon platyrhinos, the triangulation is achieved primarily through rotation of the quadrate in the transverse plane with the distal end of the quadrate moving dorsad. The quadrate is pulled by the m. cervicomandibularis acting in conjunction with one of the jaw adductors. Head triangulation in Dasypeltis scabra is produced by rotation of the quadrate mainly in the frontal plane with the distal end of the quadrate moving craniad. Experimental analysis documents that contraction of the m. adductor mandibulae externus superficialis is temporally linked to this displacement of the quadrate. The presence of two different mechanical bases for head triangulation in these distantly related colubrids suggests that this behavioural display has evolved independently in these ophidian lineages.

Defensive behaviour is one of the principal ways vertebrate hosts regulate the blood-feeding success of vector insects. Intrinsic variation in the intensity and efficiency of this biting avoidance behaviour depends on host: (1) species, (2) size, (3) age, (4) health and (5) individuality. In this paper we summarize data on the relative importance of each of these host-associated factors in regulating mosquito feeding and transmission of mosquito-borne diseases.