Alarm Pheromones and Chemical Communication in Nymphs of the Tropical Bed Bug Cimex hemipterus (Hemiptera: Cimicidae)

The recent resurge of bed bug infestations (Cimex spp.; Cimicidae) and their resistance to commonly used pesticides calls for alternative methods of control. Pheromones play an important role in environmentally sustainable methods for the management of many pest insects and may therefore be applicable for the control of bed bugs. The tropical bed bug, Cimex hemipterus, is a temporary ectoparasite on humans and causes severe discomfort. Compared to the common bed bug, Cimex lectularius, little is known about the chemical signalling and pheromone-based behaviour of the tropical species. Here, we show that the antennal morphology and volatile emission of C. hemipterus closely resembles those of C. lectularius and we test their behavioural responses to conspecific odour emissions. Two major volatiles are emitted by male, female and nymph C. hemipterus under stress, (E)-2-hexenal and (E)-2-octenal. Notably, nymph emissions show contrasting ratios of these compounds to adults and are further characterized by the addition of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal. The discovery of this nymph pheromone in C. hemipterus is potentially the cause of a repellent effect observed in the bio-tests, where nymph odours induce a significantly stronger repellent reaction in conspecifics than adult odours. Our results suggest that pheromone-based pest control methods developed for C. lectularius could be applicable to C. hemipterus, with the unique nymph blend showing promising practical properties

An embellishment that became a mutualism : Inquiries on male bee tibial bouquets and fragrance-producing orchids in Panama and oceanic islands (Apidae: Apinae, Euglossini; Orchidaceae: Epidendroideae)

We used comparative studies to investigate how and why floral and bee fragrances evolve, including courtship odors collected by male Euglossa mixta to form their tibial bouquet, on Coiba Island and other Panama forests. Fragrances of four orchid genera, two used extensively by E. mixta - Coryanthes and Mormodes - and two never used, Clowesia and Catasetum - were also analyzed. From among 636 chemicals in 93 male tibiae, 66 were also found in 30 floral head-space samples of orchids, in which 315 total volatile compounds were detected. Geographic variation was noteworthy in E. mixta, but no significant difference was found between mainland and island populations. The aromatic benzenoids methyl salicylate, 2-hydroxy-6-nona-1,3-dienylbenzaldehyde (HNDB), and the monoterpene 1,8 cineole, nearly always occurred. Coryanthes or other orchids produce two of the chemicals, but no source of HNDB is known. No statistical evidence was found of bee preference for orchids with bouquets like those formed in bee hindlegs, yet Coryanthes and Mormodes produced the most monoterpenes and more resembled the bees, when compared to Catasetum and Clowesia. Coiba bee tibial bouquets averaged 56% as diverse as on mainland and Coiba has <50% the euglossine species of nearby mainland, but lacks those most similar to E. mixta, both in phylogeny and tibial bouquet. Coiba's diverse rain forest should contain many volatiles the bees seek. Because odor collection and production are costly, our findings strengthen hypotheses that odors are used to avoid interspecific reproductive interference. Despite finding large differences in the same orchid species, we do not know whether isolation of between 107 and 104 years produced differentiation. Fragrances seem analogous among orchids and bees, thus may lessen interspecific interference or competition, and promote outcrossing or favor embellishments, via female choice. Such adaptive reasons for fragrance variation within bee or orchid populations remain largely untested

Reproductive isolation of sympatric forms of the understorey palm Geonoma macrostachys in western Amazonia

The evolution of a mechanism for attaining reproductive isolation between two diverging populations is a key step in the speciation process. We studied phenotypic variation, genetic differentiation, spatial distribution and reproductive ecology in two sympatric forms of the understorey palm Geonoma macrostachys in lowland tropical rainforest in Amazonian Ecuador. The two forms were morphologically and genetically distinct and differed in habitat preference, with one form being confined to moist flood plain habitats and the other occurring in terra firme and flood plain. Pollen transfer between the two forms was limited, but not totally prevented, by differences in flowering time, with flowers of the small form opening 2–3 h earlier than those of the large form. Differences in floral scent probably reduce the number of shared pollinators. A crossing experiment showed that pistillate flowers of either form produced fruit with pollen from the other form. We conclude that flowering biology may be a key factor in causing reproductive isolation between these closely related sympatric taxa

Long-distance pollen flow assessment through evaluation of pollinator foraging range suggests transgene escape distances

Foraging range, an important component of bee ecology, is of considerable interest for insect-pollinated plants because it determines the potential for outcrossing among individuals. However, long-distance pollen flow is difficult to assess, especially when the plant also relies on self-pollination. Pollen movement can be estimated indirectly through population genetic data, but complementary data on pollinator flight distances is necessary to validate such estimates. By using radio-tracking of cowpea pollinator return flights, we found that carpenter bees visiting cowpea flowers can forage up to 6 km from their nest. Foraging distances were found to be shorter than the maximum flight range, especially under adverse weather conditions or poor reward levels. From complete flight records in which bees visited wild and domesticated populations, we conclude that bees can mediate gene flow and, in some instances, allow transgene (genetically engineered material) escape over several kilometers. However, most between-flower flights occur within plant patches, while very few occur between plant patches