Biology subjects

Haverkamp, A.

Publications and source records attributed to Haverkamp, A..

5 recordsLinked to original sources

bioRxiv2026

Enemies, more than sex, shape butterfly post-mating odor evolution

Not all odors influencing mating behavior evolve as sex pheromones. Female butterflies post-mating odors have been considered species-specific anti-aphrodisiac pheromones shaped by sexual selection but may also serve broader ecological roles shaped by natural selection. Males transfer odors to females that repel rivals, yet the widespread use of these compounds across phyla makes them targets for eavesdropping, such as by phoretic egg parasitoids. We show that in cabbage white butterflies (Pieris spp.), these odors are highly variable and attract parasitoids, deter predators, and influence oviposition. Using gas chromatography and electroantennography, we demonstrate that odor emission and perception lack species-specificity: compounds once thought unique to P. brassicae and P. rapae are shared across Pieridae. In P. napi, odor variation among populations correlates with parasitoid pressure, but not with latitude, genetic distance, or mating frequency, suggesting ecological rather than sexual drivers. In P. brassicae, CRISPR/Cas9 disruption of odor perception alters oviposition and increases susceptibility to parasitism. Moreover, these odors render females unpalatable to birds. Together, our results show that post-mating odors in Pieris butterflies may act as aposematic signals. We provide evidence that these signals evolve under multiple selective pressures, balancing deterrence of mates and predators, parasitoid avoidance, and host-plant interactions. These findings suggest that chemical signals should be viewed as integrating ecological and reproductive pressures, rather than being interpreted solely through the lens of sexual communication.

ecology↗

bioRxiv2024

Loss of olfaction reduces caterpillar performance and increases susceptibility to a natural enemy

Insect herbivores such as caterpillars, are under strong selection pressure from natural enemies, especially parasitoid wasps. Although the role of olfaction in host-plant seeking has been investigated in great detail in parasitoids and adult lepidopterans, the caterpillar olfactory system and its significance in tri-trophic interactions remain poorly understood. In this study, we investigated the olfactory system of Pieris brassicae caterpillars and the importance of olfactory information in the interactions among this herbivore, its host plant Brassica oleracea and its primary natural enemy Cotesia glomerata. To examine the role of olfaction, we utilized CRISPR/Cas9 to knockout the odorant receptor co-receptor (Orco). This knockout (KO) impaired olfactory detection and primary processing in the brain. Orco KO caterpillars exhibited reduced weight and lost preference for their optimal food plants. Interestingly, the KO caterpillars also experienced reduced weight when challenged by the parasitoid C. glomerata whose ovipositor had been removed, and the mortality of the KO caterpillars under the attack of unmanipulated parasitoids increased. We then investigated the behavior of P. brassicae caterpillars in response to volatiles from plants attacked by conspecific caterpillars and volatiles from plants on which the caterpillars were themselves attacked by C. glomerata. After analyzing the volatile compounds involved in these interactions, we concluded that olfactory information enables caterpillars to locate suitable food sources more efficiently as well as to select enemy-free spaces. Our results reveal the crucial role of olfaction in caterpillar feeding and natural-enemy avoidance, highlighting the significance of chemoreceptor genes in shaping ecological interactions.

ecology↗

bioRxiv2021

Bees can be trained to identify SARS-CoV-2 infected samples.

The COVID-19 pandemic has illustrated the need for the development of fast and reliable testing methods for novel, zoonotic, viral diseases in both humans and animals. Pathologies lead to detectable changes in the Volatile Organic Compound (VOC) profile of animals, which can be monitored, thus allowing the development of a rapid VOC-based test. In the current study, we successfully trained honeybees (Apis mellifera) to identify SARS-CoV-2 infected minks (Neovison vison) thanks to Pavlovian conditioning protocols. The bees can be quickly conditioned to respond specifically to infected minks odours and could therefore be part of a wider SARS-CoV-2 diagnostic system. We tested two different training protocols to evaluate their performance in terms of learning rate, accuracy and memory retention. We designed a non-invasive rapid test in which multiple bees are tested in parallel on the same samples. This provided reliable results regarding a subjects health status. Using the data from the training experiments, we simulated a diagnostic evaluation trial to predict the potential efficacy of our diagnostic test, which yielded a diagnostic sensitivity of 92% and specificity of 86%. We suggest that a honeybee-based diagnostics can offer a reliable and rapid test that provides a readily available, low-input addition to the currently available testing methods. A honeybee-based diagnostic test might be particularly relevant for remote and developing communities that lack the resources and infrastructure required for mainstream testing methods.

microbiology↗

bioRxiv2019

Learning may help pollinators find their host plants in polluted landscapes

Pollination strongly contributes to food production, and often relies on pollinating insects. However, atmospheric pollution may interfere with pollination by disrupting floral plumes that pollinators use to navigate to flowers.\n\nIn this study, we examine the impacts of pollution-induced elevated ozone levels on the composition of a floral blend of Nicotiana alata and examine the response of innate and trained Manduca sexta to the ozone-altered blend.\n\nOzone exposure altered the floral blend of N. alata, and disrupted the innate attraction of naive M. sexta to the altered blend. However, associative learning can offset this disruption in attraction. Moths that were enticed with visual cues to an artificial flower emitting an ozonated blend learned to associate this blend with a nectar reward after just one rewarded experience. More importantly, moths that were rewarded while experiencing the unozonated floral blend of their host subsequently found the ozonated floral blend of the same host attractive, most likely due to experience-based reinforcement of ozone-insensitive cues in the blend.\n\nThe attraction of moths to both unaltered and ozonated plumes is critical for tolerating polluted landscapes. At the host plant, where moths feed, floral emissions are relatively pure. As floral odors travel away from the host, however, they become degraded by pollution. Therefore, targeting the flower requires recognizing both conditions of the odor. The ability to generalize between the pure and ozone-altered scents may enable pollinators like M. sexta to maintain communication with their flowers and reduce the impact anthropogenic oxidants may have on plant-pollinator systems.

animal behavior and cognition↗

bioRxiv2019

Mutagenesis of orco impairs foraging but not oviposition in the hawkmoth Manduca sexta

Plant volatile detection through olfaction plays a crucial role in insect behaviors. In vivo, the odorant receptor co-receptor orco is an obligatory component for the function of odorant receptors (ORs), a major receptor family involved in insect olfaction. We used CRISPR-Cas9 targeted mutagenesis to knock-out (KO) orco in a neurophysiological model species, the hawkmoth Manduca sexta. M. sexta and its host, the Sacred Datura (Datura wrightii) share a model insect-plant relationship based on mutualistic and antagonistic life history traits. D. wrightii is the innately preferred nectar-source and oviposition host for M. sexta. Hence, the hawkmoth is an important pollinator while the M. sexta larvae are specialized herbivores of the plant. We generated an orco KO through CRISPR-Cas9 to test the consequences of a loss of OR-mediated olfaction in this insect-plant relationship. Neurophysiological characterization revealed severely reduced antennal and antennal lobe responses to representative odorants emitted by D. wrightii. In a wind-tunnel setting with a flowering plant, orco KO hawkmoths showed disrupted flight orientation and an ablated proboscis extension response to the natural stimulus. However, when testing the oviposition behavior of mated females encountering a non-flowering plant, there was no difference between orco KO and wild type females regarding upwind flight orientation and number of eggs laid. Overall, OR-mediated olfaction is essential for foraging and pollination behaviors, but plant-seeking and oviposition behaviors appear largely unaffected. Significance statementInsects detect plant volatiles mainly through the expression of ORs and IRs on the antennal olfactory sensory neurons (OSNs). In vivo, Orco is an obligate partner for OR, but not IR function and ORs mediate a vast spectrum of olfactory perception. We applied CRISPR-Cas9 in M. sexta to mutate the orco gene and determine the physiological and behavioral implication of a loss of Orco receptor function in a semi-ecological interaction with D. wrightii. We found that while behaviors related to foraging were largely disrupted, other sensory modalities outside Orco function determine the relationship between an ovipositing female and its plant host. These results have implications toward understanding the olfactory basis of insect-plant interactions shaping our ecological and agricultural landscapes.

neuroscience↗