Pheromones and body coloration affect mate recognition in the Japanese nine-spotted moth Amata fortunei (Lepidoptera: Arctiidae)

Brain size scaling through development in the whitelined sphinx moth (Hyles lineata) shows mass and cell number comparable to flies, bees, and wasps

Factors regulating larval growth and determinants of adult body size are described for several holometabolous insects, but less is known about brain size scaling through development. Here we use the isotropic fractionation ("brain soup") method to estimate the number of brain cells and cell density for the whitelined sphinx moth (Lepidoptera: Hyles lineata) from the first instar through the adult stage. We measure mass and brain cell number and find that, during the larval stages, body mass shows an exponential relationship with head width, while the total number of brain cells increases asymptotically. Larval brain cell number increases by a factor of ten from nearly 8000 in the first instar to over 80,000 in the fifth instar. Brain cell number increases by another factor of 10 during metamorphosis, with the adult brain containing more than 900,000 cells. This is similar to increases during development in the vinegar fly (Drosophila melanogaster) and the black soldier fly (Hermetia illucens). The adult brain falls slightly below the brain-to-body allometry for wasps and bees but is comparable in the number of cells per unit brain mass, indicating a general conservation of brain cell density across these divergent lineages.

Comparative analysis on visual and olfactory signals of Papilio xuthus (Lepidoptera: Papilionidae) during foraging and courtship

This study examined the roles of visual and olfactory responses during foraging and courtship in butterfly Papilio xuthus. P. xuthus showed obvious orientation to color in the range of 350–500 nm. Visits of P. xuthus females and males to blue, purple, and red artificial cloth flowers were ♀ 54.90% and ♂ 39.22%, ♀ 19.61% and ♂ 35.29%, and ♀ 9.80% and ♂ 19.61%, respectively. Application of 10% honey on these artificial flowers resulted in an increase of 3.41 and 3.26 fold in flower visits by the butterfly compared to controls. When 10% honey water was sprayed on flower branches without colorful flowers, branch visiting was very low, only seven times for females and two times for males, indicating that colors might be more critical than odor for foraging even though visual and olfactory perceptions both play important roles during foraging. During courtship, four types of chasing were observed in a natural population of P. Xuthus; the four types are males chasing females (49%), males chasing males (25%), females chasing males (13%), and females chasing females (10%). However, when odorless artificial models of butterflies were used, no significant differences were observed among these types of chasing, indicating that olfactory perception was crucial for the butterfly during courtship. Profiling volatile organic chemicals (VOCs) and individual bioassays revealed that VOCs contents of butterflies were not related to recognizing sex partners; by contrast, some level of α-farnesene, increased the frequency of male chasing female. This could be due to that α-farnesene is easy to be detected by butterflies because of its volatility and higher content in female.

Identification of the sex pheromone of the diurnal hawk moth, Hemaris affinis

Sex pheromones of nocturnal hawk moths have been identified previously, but not those of diurnal hawk moths. Here, we report laboratory analyses and field testing of the sex pheromone of the diurnal hawk moth, Hemaris affinis (Bremer 1861) (Lepidoptera: Sphingidae). Sex pheromone glands were removed and extracted in hexane during peak calling activity of virgin female moths. Analysis of gland extracts by gas chromatography (GC) with electroantennographic detection revealed three components that elicited responses from male moth antennae. These components were identified, based on their mass spectra and retention indices on two GC columns, as (Z)-11-hexadecenal and (10E, 12Z)- and (10E,12E)-10,12-hexadecadienals with a ratio of 45:20:35. In a field experiment, traps baited with the three-component synthetic blend, but none of the single- or two-component blends, caught male moths. All three pheromone components have been identified previously in pheromones of other Lepidoptera, including Sphingid moths, and thus the ternary blend is probably responsible for the species specificity of the pheromone of this moth.

Semiochemical and Vibrational Cues and Signals Mediating Mate Finding and Courtship in Psylloidea (Hemiptera): A Synthesis

Mate finding and courtship involve complex interactions that require close coordination between individuals of the opposite gender. Well-organized signalling systems, sometimes involving a combination of signal modalities, are required to convey species-specific and individual information to members of the opposite gender. Previous studies of psyllids have focused on single-signal modalities and have largely ignored the potentially interdependent nature of different types of signals. Several studies have shown that semiochemicals play a role in psyllid mate finding. However, long-range semiochemical sex attractants, such as the highly volatile sex pheromones used by many Lepidoptera (molecular weights <300), are yet to be identified. The compounds identified thus far, namely 13-methylheptacosane (from Cacopsylla pyricola) and dodecanoic acid (from Diaphorina citri), seem to have short range activity or no activity under field conditions. The possible role played by cuticular hydrocarbons in psyllid courtship remains largely ignored. Conversely, many psyllid species rely on vibrational signals for mate finding and mate assessment during courtship. This apparent disproportional reliance on vibrational rather than semiochemical signals suggests that vibrational signals have been more influential in sexual selection in psyllids. However, male fitness, female choice and benefits accrued from selecting fitter males remain poorly understood.