Exotic grass invasion impacts fitness of an endangered prairie butterfly, <Emphasis Type="Italic">Icaricia icarioides fenderi</Emphasis>

Fender’s blue butterfly is an endangered species restricted to fragmented, grassland remnants that are becoming increasingly dominated by tall, invasive grasses in western Oregon, USA. I performed a removal experiment to assess the impacts of structural degradation accompanying the invasion of Arrhenatherum elatius, tall oat grass, on butterfly fitness and fitness related behaviors. Clipping of A. elatius to native grass sward height resulted in 2.5–5 times as many eggs laid per leaf of host plant. Both male and female butterflies basked more frequently in areas removed of A. elatius inflorescences and upon encountering the treatment edge butterflies had a high rate of return into a large area removed of the grass inflorescences. Although butterfly behavior appeared to be affected by the change in sward height on the treatment edge, there was no evidence for the edge causing a disproportionate egg load. Invasion and dominance by A. elatius appeared to diminish host plant apparency which may result in overloading of eggs on conspicuous host plants, increased incidence of emigration, and a decrease in the likelihood of colonization because female butterflies appeared indifferent to larval resources beneath A. elatius inflorescences. Dominance of natural shortgrass prairies by tall stature grasses like A. elatius may be an insidious form of habitat degradation for grassland Lepidoptera worldwide, but it may go largely unnoticed because larval and adult resources can persist under the unnaturally tall grass canopy.     

Molecular and functional characterization of Anopheles gambiae inward rectifier potassium (Kir1) channels: A novel role in egg production

Inward rectifier potassium (Kir) channels play essential roles in regulating diverse physiological processes. Although Kir channels are encoded in mosquito genomes, their functions remain largely unknown. In this study, we identified the members of the Anopheles gambiae Kir gene family and began to investigate their function. Notably, we sequenced the A. gambiae Kir1 (AgKir1) gene and showed that it encodes all the canonical features of a Kir channel: an ion pore that is composed of a pore helix and a selectivity filter, two transmembrane domains that flank the ion pore, and the so-called G-loop. Heterologous expression of AgKir1 in Xenopus oocytes revealed that this gene encodes a functional, barium-sensitive Kir channel. Quantitative RT-PCR experiments then showed that relative AgKir1 mRNA levels are highest in the pupal stage, and that AgKir1 mRNA is enriched in the adult ovaries. Gene silencing of AgKir1 by RNA interference did not affect the survival of female mosquitoes following a blood meal, but decreased their egg output. These data provide evidence for a new role of Kir channels in mosquito fecundity, and further validates them as promising molecular targets for the development of a new class of mosquitocides to be used in vector control.     

Oviposition behaviour of the grasshopper Zonocerus variegatus

Abstract. 1. Long-term changes in the numbers of Zonocerus at oviposition sites reflect changes in the maturity of the general population.
2. Short-term changes in the numbers of Zonocerus at oviposition sites are associated partly with normal diurnal behaviour in which roosting occurs at night.
3. Immigration of Zonucems , particularly females, into the oviposition site occurs prior to periods of oviposition activity. Emigration follows oviposition.
4. The majority of Zonocerus move upwind into the oviposition site suggesting an odour and/or sound attraction.
5. Periods of intense oviposition activity follow heavy rainfall.     

Daily Rhythms Related to Distinct Social Tasks inside an Eusocial Bee Colony

A bee colony is often compared to a multicellular organism, mainly because of its spatial organization. We propose that a temporal organization of equal importance is also present. To support this view, we studied the reproductive processes of two closely related species of stingless bees. Stingless bees enable observations of daily rhythms that are performed by distinct social classes. The emergent process, POP, is cyclic and consists of the building and provisioning of brood cells by the worker bees and egg‐laying by the queen. Colonies were kept in the laboratory under constant conditions with the exit tube opening to the environment; thus, foragers had direct access to environmental cycles. At a later stage of the experiment, the exit tube was closed by a sieve; in this case, bees had their own stock of food, but the environmental LD cycle could still be detected when they were inside the exit tube. Daily POP rhythms were present and showed distinct temporal patterns in each species. A third condition was imposed on one of the species only: the exit tube was closed by a sieve and maintained inside a box that was provided with constant illumination. In this colony, the POP rhythm was perturbed by the destruction of the brood cells. Restoration of POP consisted of a rapid reconstruction of cells followed by a late oviposition in the same day. As different rhythmic patterns were detected, but showed regular timings with respect to one another, an interpretation based upon the concept of an internal temporal order is suggested.     

Semi-field demographic performance of the invasive planthopper,Orosanga japonica (Hemiptera: Ricaniidae) on two host plants

Orosanga japonica Melichar (Hemiptera: Ricaniidae) is an invasive polyphagous pest in Iran. The planthopper damaged host plants by sap-sucking and egg laying on new twigs. This study aimed to determine the life table parameters of O. japonica on Rubus ulmifolius Schoot (elm leaf blackberry) and Melia azedarach L. (chinaberry) under field conditions in Rudsar (North of Iran) during 2019–2020. The collected life history data were analyzed based on age-stage, two-sex life table theory. The results showed that the incubation period of O. japonica was too long (≈ 270 days) on both host plants. The nymphs emerged from mid-May 2020. The planthopper had five nymphal stages under field conditions. The nymphal duration was 41.39 ± 0.56 days and 38.13 ± 0.62 days on R. ulmifolius and M. azedarach, respectively. The total preadult survival rates were 53.2% and 51.7% on R. ulmifolius and M. azedarach, respectively. Based on the results, a significant shorter total developmental time was observed on M. azedarach. When adults emerged in late July, they laid eggs after 26.05 days and 26.75 days on R. ulmifolius and M. azedarach, respectively. The fecundity on M. azedarach (131.69 egg/female) was significantly higher than that on R. ulmifolius. However, the life table parameters were all not significantly different on the two host plants. The intrinsic rate of increase (r) were 0.0097 ± 0.0005 day⁻¹ and 0.0105 ± 0.0006 day⁻¹ on R. ulmifolius and M. azedarach, respectively. Generally, these findings could be helpful to establish an efficient management strategy for this exotic pest.