Plant-mediated synthesis of nanoparticles:A newer and safer tool against mosquito-borne diseases?

Prevention and control of mosquito-borne diseases is a key challenge of huge public health importance.Plant-mediated synthesis of nanoparticles has recently gained attention as a cheap,rapid and eco-friendly method to control mosquito vector populations,with special reference to young instars.Furthermore,plant-fabricated nanoparticles have been successfully employed as dengue virus growth inhibitors.In this Editorial,parasitologists,entomologists and researchers in drug nanosynthesis are encouraged to deal with a number of crucial challenges of public health importance.

Neem by-products in the fight against mosquito-borne diseases:Biotoxicity of neem cake fractions towards the rural malaria vector Anopheles culicifacies(Diptera:Culicidae)

Objective: To evaluate the ovicidal, larvicidal and adulticidal potential of neem cake fractions of different polarity against the rural malaria vector Anopheles culicifacies(An.culicifacies).Methods: Neem cake fractions' total methanol extract(NTMeOH), total ethyl acetate extract(NTAc OEt), ethyl acetate fraction after repartition with NTMe OH(NRAc OEt),butanol fraction after repartition with NTMeOH(NRBuOH), and aqueous fraction after repartition of NTMeOH(NRH2O) were tested against An. culicifacies eggs, fourth instar larvae and adults.Results: In larvicidal experiments, NTMeOH, NTAcOEt, NRAcOEt, NRBuOH and NRH2O achieved LC50 values of 1.32, 1.50, 1.81, 1.95 and 2.54 mg/L, respectively. All fractions tested at 150 mg/L were able to reduce egg hatchability of more than 50%, with the exception of NTAc OEt and NRAc OEt. In adulticidal assays, NTMeOH, NTAcOEt,NRAcOEt, NRBuOH and NRH2O achieved LC50 values of 3.01, 2.95, 3.23, 3.63 and3.00 mg/L, respectively.Conclusions: Overall, this study suggests that the methanolic fractions of neem cake may be considered as a new and cheap source of highly effective compounds against the rural malaria vector An. culicifacies.

Spread of Zika virus:The key role of mosquito vector control

Mosquitoes(Diptera: Culicidae) represent a key threat for millions of humans and animals worldwide, since they act as vectors for important parasites and pathogens,including malaria, filariasis and a wide number of arboviruses. The recent outbreaks of Zika virus infections occurring in South America, Central America, and the Caribbean,represent the most recent four arrivals of important arboviruses in the western hemisphere, over the last 20 years, namely dengue, West Nile virus, and chikungunya. Since there are no specific treatments for Zika virus and the other arboviruses mentioned above,it should be highlighted that the eco-friendly and effective control of mosquito vectors is of pivotal importance. Besides radiation, transgenic and symbiont-based mosquito control approaches, an effective option may be the employ of biological control agents of mosquito young instars, in presence of ultra-low quantities of green-synthesized nanoparticles, which magnify their predation efficiency. Furthermore, behaviour-based control tools relying on the employ of swarming behaviour manipulation(i.e. the "lure and kill"approach), pheromone traps, sound traps need further research attention. In particular,detailed basic information on the physical and chemical cues routing mosquito swarming and mating dynamics is urgently required.

Insecticide susceptibility in larval populations of the West Nile vector Culex pipiens L.(Diptera: Culicidae) in Saudi Arabia

Objective: To investigate the susceptibility to some conventional and non-conventional insecticides in laboratory and field larval populations of the West Nile vector Culex pipiens L.(Cx. pipiens), the dominant species in Jeddah Province, Saudi Arabia.Methods: The tested conventional insecticides were Actikil and Pesgard, while the nonconventional ones were Bacilod, Dudim and Baycidal. Probit analysis and photomicroscopical observations were carried out to shed light on acute toxicity in laboratory and field Cx. pipiens strains.Results: Cx. pipiens were more susceptible to Pesgard(LC50: 0.045 and 0.032 mg/L)than Actikil(0.052 and 0.038 mg/L) and Bacilod(0.129 and 0.104 mg/L), for the field and laboratory strains, respectively. Results showed that treatments with the chitin synthesis inhibitor Dudim and Baycidal evoked morphological effects similar to those induced by other insect growth regulators. According to IC50 values obtained(concentration which to inhibit the emergence of 50% of mosquito adults), the compound Dudim(0.000 3 and 0.000 1 mg/L) was more effective against Cx. pipiens L. mosquitoes than Baycidal(0.000 4 and 0.000 3 mg/L) for both the field and laboratory strains, respectively.Conclusions: Our results provide baseline data to enhance control programs and orient public health decisions on the selection of pesticides against mosquito vectors in Saudi Arabia.

Is bigger better？ Male body size affects wing-borne courtship signals and mating success in the olive fruit fly, Bactrocera oleae （Diptera： Tephritidae）

Variations in male body size are known to affect inter- and intrasexual selection outcomes in a wide range of animals. In mating systems involving sexual signaling before mating, body size often acts as a key factor affecting signal strength and mate choice. We evaluated the effect of male size on courtship displays and mating success of the olive fruit fly, Bactrocera oleae （Diptera： Tephritidae）. Wing vibrations performed during successful and unsuccessful courtships by large and small males were recorded by high-speed videos and analyzed through frame-by-frame analysis. Mating success of large and small males was investigated. The effect of male-male competition on mating success was evaluated. Male body size affected both male courtship signals and mating outcomes. Successful males showed wing-borne signals with high frequencies and short interpulse intervals. Wing vibrations displayed by successful large males during copulation attempt had higher frequencies over smaller males and unsuccessful large males. In no-competition conditions, large males achieved higher mating success with respect to smaller ones. Allowing large and small males to compete for a female, large males achieve more mating success over smaller ones. Mate choice by females may be based on selection of the larger males, able to produce high-frequency wing vibrations. Such traits may be indicative of ＂good genes,＂ which under sexual selection could means good social-interaction genes, or a good competitive manipulator of conspecifics.

Singing on the wings! Male wing fanning performances affect female willingness to copulate in the aphid parasitoid Lysiphlebus testaceipes （Hymenoptera： Braconidae： Aphidiinae）

Lysiphlebus testaceipes （Hymenoptera： Braconidae： Aphidiinae） is a generalist endoparasitoid attacking more than 100 aphid species. In L. testaceipes, wing fanning is a main male courtship display evoked by a female-borne sex pheromone. However, no information is available on the characteristics and behavioral role of male fanning during courtship in this parasitoid. Here, the courtship behavior of a wild strain ofL. testaceipes was quantified and the male wing fanning performances were analyzed through high-speed video recordings and examined in relation to mating success. Courtship sequence of wild L. testaceipes did not substantially differ from that previously reported for other populations mass reared on aphids. We observed that the male courtship duration did not affect mating success. However, video analysis revealed that the males producing high-frequency fanning signals achieved higher mating success over those that display low-frequency fanning. Wing fanning before successful and unsuccessful courtship differed in amplitude of wing movements and alignment toward the mate, highlighting that frontal courtship positively influence the female mating decisions. This study increases knowledge on sexual behavior in a key parasitoid of aphids, highlighting the importance of wing fanning among the range of sensory modalities used in the sexual communication ofL. testaceipes. From a practical point of view, this information is useful in L. testaceipes-based biocontrol strategies, since it can help to establish parameters for quality checking of mass-reared wasps over time.

Together We Stand-Analyzing Schooling Behavior in Naive Newborn Guppies through Biorobotic Predators

A major advantage of animal aggregations concerns cooperative antipredator strategies.Schooling behavior emerges earlier in many fish species,especially in those cannibalizing their offspring.Experience is fundamental for developing schooling behavior.However,the cognitive ability of naive newborn fish to aggregate remains unclear.Herein,Poecilia reticulata,was selected as model organism to investigate how combinations of biomimetic robotic agents and adult conspecific olfactory cues affect collective responses in newborns.The role of white and brown backgrounds in evoking aggregations was also assessed.Olfactory cues were sufficient for triggering aggregations in P.reticulata newborns,although robotic agents had a higher influence on the group coalescence.The combination of robotic agents and olfactory cues increased schooling behavior duration.Notably,schooling was longer in the escape compartment when robotic agents were presented,except for the combination of the male-mimicking robotic fish plus adult guppy olfactory cues,with longer schooling behavior in the exploring compartment.Regardless of the tested cues,newborn fish aggregated preferentially on the brown areas of the arena.Overall,this research provides novel insights on the early collective cognitive ability of newborn fish,paving the way to the use of biomimetic robots in behavioral ecology experiments,as substitutes for real predators.

Wing-fanning frequency as a releaser boosting male mating success— High-speed video analysis of courtship behavior in Campoplex capitator, a parasitoid of Lobesia botrana

Campoplex capitator is an ichneumonid parasitoid with a narrow host range,comprising grapevine moth pests.Despite being considered one of the possible candidates for biocontrol of Lobesia botrana,knowledge about its biology is limited and massrearing for commercial purposes is still lacking.This research provides a quantitative analysis of the C.capitator courtship and mating behavior.C.capitator mating sequence was analyzed by high-speed video recordings.Main behavioral parameters,with special reference to male wing fanning and antennal tapping,were quantified and linked with mating success.Furthermore,we analyzed the occurrence of population-level behavioral asymmetries during C capitator sexual interactions and their impact on male success.Results showed that male wing fanning was crucial to successfully approach the female.Males achieving higher mating success performed wing-fanning at higher frequencies over unsuccessful ones.After wing fanning,most of males palpated the females body with their antennae,before attempting copulation.The overall mating success was>70%,with a rather long copula duration(254.76±14.21 s).Male wing-fanning was lateralized on the left at population level,while antennal tapping displays were right-biased.Sidebiased male displays do not differ in terms of frequency and duration of their main features.This research adds basic knowledge to the C.capitator behavioral ecology.Since rearing protocols for C.capitator are being developed male wing fanning frequency may represent a useful benchmark for monitoring mate quality over time,tackling mating success reductions due to prolonged mass-rearing.

Organic-inorganic hybrid fluorescent sensor thin films of rhodamine B embedded Ag-SBA 15 for selective recognition of Hg(Ⅱ)ions in water

Nowadays, the rapid and effective detection of low doses of heavy metal pollutants in contaminated water is a timely challenge in environmental pollution research. In this study, a rapid and highly sensitive assay for the detection of Hg^2＋based on quenching of metal-enhanced fluorescence of rhodamine B（RB）has been fabricated. RB and silver nanoparticle were incorporated into the mesoporous siliceous framework spin cast on a quartz glass through post-synthetic incorporation method. The morphology and crystallinity of mesoporous structure and Ag nanoparticle were characterized by transmission electron microscopy and X-ray diffraction analyses. Photoluminescence assays on the hybrid thin film of RB-Ag-SBA15 showed a high enhancement when compared to the intensity of silver free SBA15-RB in the wavelength of 575 nm. The fluorescence of RB-Ag-SBA15 thin film decreased gradually with the increase in the concentration of Hg^2＋and the detection limits were 10.54 nmol/L. Furthermore, the fluorescence intensity increased linearly with the concentration of Hg^2＋in the range from 1.0 ×10^-8mol/L to10× 10^-8mol/L, with a response time of a few seconds. In addition, this system offers a high selectivity over interfering cations such as Cd^2＋ and Pb^2＋. Overall, we have developed an optical assay having a wellordered mesoporous SBA15 containing Ag-RBfor selective detection of Hg^2＋in aqueous solution. The scheme combines the advantages of specific binding interactions between Hg^2＋and RB molecule and optical emission properties of RB. The method is suitable for a single-shot and irreversible analytical assay in a quartz glass/microtiter plate.