Oviposition biology, behavior, and avocado cultivar preferences of Heilipus lauri Boheman (Coleoptera: Curculionidae).

Heilipus lauri is a specialist avocado seed feeding weevil native to parts of México and is an invasive pest in Colombia. This weevil is considered an incursion risk because possible unintended introductions into areas outside of its native range can result in establishment, which threatens avocado production in invaded regions. Despite being a well-recognized pest of avocados, relatively little is known about oviposition biology, behavior, and cultivar preferences of this weevil. Field studies in commercial Hass avocado orchards in México and laboratory studies in a quarantine facility in California (USA) indicated that H. lauri prefers to oviposit into middle and bottom thirds of fruit. In the laboratory, an average of 1.7 eggs (range 1-6 eggs) are laid over a 24-h period in oviposition chambers by individual females. Conspecifics add eggs to these clutches, with up to 17 eggs being recorded in 1 oviposition chamber. This finding suggests that H. lauri does not use an oviposition deterring pheromone. Female weevils readily oviposit in artificial holes representing mechanical wounds on fruit. In comparison to the commercially dominant Hass variety, fruit from Lamb Hass and G22, a native Guatemalan variety, and to a lesser extent Gem, may be less preferred for oviposition when females have a choice of fruit in which to oviposit. Videography studies indicated that H. lauri exhibits predominantly diurnal activity with respect to oviposition behaviors, feeding, and walking.

Oviposition behavior of the parasitoid Telenomus remus (Hymenoptera: Scelionidae) on eggs of Spodoptera frugiperda (Lepidoptera: Noctuidae).

Telenomus remus (Hymenoptera: Scelionidae) is an efficient parasitoid of Spodoptera eggs. However, biological control programs require taxonomic, bioecological and behavioral studies of biological agents. Although the performance of T. remus in pest control has been evaluated, little is known about its behavioral aspects that can influence IPM tactics. The aim of this study was therefore to study the parameters related to the oviposition behavior of T. remus on Spodoptera frugiperda (Lepidoptera: Noctuidae) eggs. The experiment was conducted in the laboratory, where 17 females were transferred individually to arenas containing a mass of S. frugiperda eggs. Oviposition behavior was recorded for 30 minutes. The average walking speed of the females was 0.116 mm.s-1 and the total distance covered was 203.3 mm. The females remained on the egg masses for an average of 16.7 min, which corresponds to more than half of the total time. The average number of parasitized eggs was 15.1 per female in 30 minutes. Females with larger antennae had lower values for average speed and total distance covered. The results of the parameters evaluated show the standard oviposition behavior of T. remus females on S. frugiperda eggs and help us to better understand the species.

The effect of addition of calcium mineral in feed containing fishery wastes on egg production and hatching performance of Mojosari ducks.

Calcium (Ca) is an essential mineral for eggshell formation and muscle contraction, and a lack of it can result in poor egg quality and decreased egg output in laying ducks. This study aims to see how feeding the mineral Ca in a ration containing Shrimp head meal and Bilis fish head affects the laying performance and quality of hatching eggs in Mojosari ducks. A total of 105 female and 15 male Mojosari ducks, aged 78 weeks, were raised for three months and randomly divided into 15 flocks (each flock containing seven females and one male duck). There were three kinds of treatment, namely P0 (control, without mineral), P1 (ratio of Shrimp head meal and Bilis fish head 2:1 + 1% mineral), and P2 ((ratio of Shrimp head meal and Bilis fish head 1:2 + 1% mineral). The findings revealed that adding mineral Ca to feed, including Shrimp head meal and Bilis fish head, had no significant influence (P>0.05) on laying Mojosari duck performance in terms of feed intake, egg production, egg weight, egg quality, ducklings produced, and income over feed cost (IOFC). Furthermore, Ca addition in the ration did not result in substantial increases (P>0.05) in fertility, hatchability, or egg size characteristics. Based on the findings of this study, feeding ducks with shrimp head meal and Bilis fish head can be used as an alternate calcium-free feed formulation.

Exudate droplets incorporated on eggs by Raoiella indica Hirst female during oviposition may avoid the predation of Amblyseius largoensis (Muma).

Raoiella indica Hirst has rapidly and widely spread throughout the New World since 2004, primarily infesting coconut palms and interacting with the predator Amblyseius largoensis (Muma). Although A. largoensis feeds on R. indica at all stages of development, it cannot naturally reduce its population to levels that do not impact the host plant. Raoiella indica possesses dorsal setae that secrete exudates during all post-embryonic developmental stages, and females have a behavior that deliberately deposits droplets on the freshly laid egg, possibly as a defense strategy against predation in vulnerable stages. In this context, we analyzed whether the presence or absence of droplets in R. indica eggs affects predation using A. largoensis as a biological model. Thus, we evaluated whether some biological and behavioral characteristics of A. largoensis could be affected by the consumption of R. indica egg masses washed or unwashed with water. Also, we performed a chemical analysis of the droplets exuded by R. indica and provided a description of the oviposition behavior of R. indica. The predator showed a higher consumption rate and preference for washed eggs. The results suggest that the exudate droplets have defensive functions, which are incorporated by the female onto the egg during oviposition and subsequently during a patrolling behavior, as they lose their effect after being washed with water. Although the droplets do not prevent the predator from feeding, they reduce the number of R. indica eggs consumed without affecting the growth of A. largoensis.

Neem-Extract Formulation on Hypothenemus hampei Preference and Performance in Arabica Coffee Fruits and Artificial Diet.

Coffee berry borer (CBB) Hypothenemus hampei is a major biotic threat to coffee production worldwide. Studies have reported negative effects on CBB by oil-based formulations of neem (Azadirachta indica), but little information is available for other neem-extract formulations. This study evaluated CBB preference and performance in arabica coffee fruits and artificial diet treated with a neem-extract formulation (Openeem Plus®) in the field and laboratory conditions. Field experiments were performed using CBB females artificially infested in cherry or green coffee fruits confined in voile-fabric cages tied to branches of neem-treated and control plants, recording the adult mortality and offspring production. Dual-choice and no-choice bioassays assessed CBB preference and development in fruits and artificial diet treated with the neem extract compared to controls in the laboratory, respectively. As main results obtained in the field and laboratory experiments, the neem extract significantly reduced CBB oviposition in both cherry and green fruits, as well as in artificial diet compared to controls. However, the botanical product did not affect CBB adult survival and preference in the laboratory bioassays. The neem extract is promising for use in pest management strategies in sustainable arabica coffee crops by reducing CBB oviposition and offspring. These effects can contribute to lowering the pest population buildup along the crop cycle and damage potential to coffee production.

Polyandry contributes to Gonipterus platensis (Coleoptera: Curculionidae) rearing.

Background: Gonipterus platensis Marelli, 1926 (Coleoptera: Curculionidae) is one of the main defoliating beetles in Eucalyptus plantations. Biological control with egg parasitoids is one of the main control strategies for this pest and a constant supply of fresh host eggs is required to rear the parasitoids. Polyandry can influence Gonipterus oviposition by increasing female fecundity and fertility; however, the high density of individuals in laboratory colonies can lead to male harassment, resulting in lower reproduction rate. The aim of this study was to measure the effects of monoandry and polyandry on the reproduction of G. platensis and the effects of male harassment on laboratory rearing conditions. Methods: Reproductive parameters were compared between three treatments: monoandry, where the female was allowed to mate daily with the same male; no choice polyandry, where the female was allowed to mate daily with a different male; and polyandry with choice, where the female was allowed to mate daily, but with a choice between five different males. Another experiment varying the density of males was conducted to evaluate the effect of male harassment. Results: Polyandry with choice resulted in the longest period of oviposition, highest fecundity and highest number of eggs per egg capsules when compared to monoandrous females. No negative effect related to male harassment in the laboratory, such as decreased fertility, fecundity, or number of eggs per egg capsule, was detected. Conclusion: Polyandry contributes to mass rearing as it increases fecundity and oviposition period on females and there is no evidence of male harassment on G. platensis.

Male condition and seminal fluid affect female host-marking behavior in the Mexican fruit fly.

Mating and the transfer of seminal fluid components including male accessory glands (MAGs) proteins can affect oviposition behavior in insects. After oviposition, some species of fruit flies deposit a host-marking pheromone (HMP) on the fruit that discourages oviposition by other females of the same or different species or genus and reduces competition between larvae. However, we know very little about how mating, receiving seminal fluid, or male condition can affect female host marking behavior. Here, we tested how the physiological state of females (mated or unmated), the receipt of seminal fluid, and the condition of the male (wild or sterile) affect oviposition and host-marking behavior (HMB) in Anastrepha ludens (Diptera: Tephritidae). We also determined the efficiency of the host-marking pheromone from mated or unmated females in deterring oviposition. In a further examination of how seminal fluid may be affecting HMB we assessed if there were differences in the size of wild or sterile MAGs and the protein quantity transferred during mating. Our results indicate that receiving seminal fluid increased egg laying and increased time invested in host-marking (HM). Unmated females laid fewer eggs than mated females but invested the same amount of time in depositing host-marking pheromone, which had similar effectiveness in deterring oviposition as that of mated females. Females that mated with sterile males laid the same number of eggs as females that mated with wild males but spent less time depositing host-marking pheromone, which suggests that females detect the condition of the male and invest less in marking hosts. Finally, sterile males had larger accessory glands and transferred more MAGs proteins during mating compared to wild males. Seminal proteins could be manipulating HM behavior and female investment into their current reproductive effort. We are only beginning to understand how male condition and seminal fluid can affect female physiology and maternal investment in HMP.

EVALUATION OF THE EFFICIENCY OF BEETROOT PEEL (BETA VULGARIS) IN OVITRAPS AS AN ATTRACTANT FOR SURVEILLANCE OF ARBOVIRUS VECTORS IN THE MUNICIPALITY OF AGRESTINA, STATE OF PERNAMBUCO, BRAZIL.

It is estimated that there are over 500 species of arboviruses worldwide, with more than 150 of them directly associated with human diseases, the majority of which are zoonotic. Among the main arboviruses circulating in Brazil, dengue, Zika, and chikungunya stand out, all transmitted through a common vector, Aedes aegypti. Given this scenario, the development and implementation of more efficient surveillance strategies become urgent. This study aims to compare and evaluate the efficiency of beetroot peel, Beta vulgaris, as an attractant for Ae. aegypti oviposition under field conditions in the municipality of Agrestina, State of Pernambuco, Brazil. Beetroot peel extract is a cheap and accessible source of geosmin, which holds significant potential as an attractant for mosquitoes due to its resemblance to microbial volatiles found in water bodies rich in organic material. During the study period (November 2023 to April 2024), 40 traps were set in each neighborhood, with 20 of each attractant. Two traps were used per property, one following the traditionally used model (beer yeast infusion) and another containing beetroot peel. Overall, in both analyzed neighborhoods (Campo Novo and Cohab), beetroot peel appeared to be a more efficient attractant for the oviposition of culicids. Beetroot peel showed the highest values in egg abundance and in the analyzed indices.

Mating behavior and oviposition of Palpita forficifera (Lepidoptera: Crambidae).

Palpita forficifera Munroe, 1959 (Lepidoptera: Crambidae) is considered the main pest of the olive tree (Olea europaea L., Oleaceae) in Brazil and Uruguay. The aim of this work was to study the mating and oviposition behavior of P. forficifera in the field and laboratory. In the field, the sex emitting the mating pheromone was determined and in the laboratory, the rate of emergence of males and females; the age, time and duration of mating; number of copulations and oviposition time of P. forficifera were recorded. The field results showed that it was possible to capture up to five males per trap in just one night in traps with the presence of female P. forficifera. Copulation occurs between the seventh and twenty-third day of life and is most frequent during the third and sixth hours of scotophase. The average duration of the first copulation was 174 min, with 35% of couples recopulating, and there were cases of up to five copulations. Oviposition times were concentrated between 20:00 and 02:00. The results obtained provide insight into the reproductive behavior of P. forficifera and are useful for future studies aimed at identifying the sex pheromone to improve monitoring of the pest in olive orchards.

Diflubenzuron larvicide auto-dissemination: A modeling study.

Proposing substitutes for Pyriproxyfen (PPF) in the auto-dissemination strategy is essential to ensure the continuity of the strategy in the field, especially in the case of the emergence of populations resistant to this larvicide. One possible substitute among the compounds already in use in Brazil is the larvicide Diflubenzuron (DFB). The equation that defines the proportion of oviposition sites (habitats) contaminated by the auto-dissemination strategy was modified to account for the number of visits required to reach the necessary concentration of DFB for contamination, considering scenarios with varying numbers of oviposition sites and mosquito densities. The dissemination was evaluated in oviposition sites of 2 L, 1.5 L, 1 L, 0.5 L, 0.2 L, and 0.1 L. The minimum concentration of active ingredient (a.i) of DFB required for a commercial product to contaminate at least 50% of oviposition sites was also investigated, along with the impact of other vector control methods, such as the removal/destruction of oviposition sites and the use of insecticides to kill adult 'females, on the auto-dissemination approach. The use of pure DFB compounds enabled contamination efficiency of more than 50% in oviposition sites with a volume of less than 2 L in scenarios with fewer oviposition sites. On the other hand, with the use of the commonly used concentration of the product, similar efficacy was only achieved in oviposition sites of 0.1 L and 0.2 L in medium and high infestation scenarios. Strategies that reduce the number of available oviposition sites work synergistically with the auto-dissemination strategy, making it possible to use less concentrated products and contaminated sites of larger volume. The strategy proved to be resilient in situations of insecticide application according to the concentration of DFB used, abundance of females, and low number of oviposition sites. Increasing the number of dissemination traps on the field also contributes to better results, especially for oviposition sites of 0.5 L and 1 L. The results of the model obtained under the stipulated conditions provide further support for the potential use of DFB as a substitute for PPF in the auto-dissemination strategy.

Life history of the two predacious mites species, Amblyseius swirskii, and Neoseiulus cucumeris (Acari: Phytoseiidae), as biological control agents of the date palm mite, Oligonychus afrasiaticus (Acari: Tetranychidae).

The date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), is a serious pest of dates in the Middle East and North Africa, inflicting severe economic damage if not controlled early. As predaceous mites are known to be potential biocontrol agents against several pests, so predation capacity, life table, reproduction, and survival of Amblyseius swirskii Athias-Henriot and Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), collected from date palm farms in Qassim Saudi Arabia, were studied under laboratory conditions (25 °C, 30 °C, 35 °C and 50 ± 5% RH) against all motile stages of O. afrasiaticus. For both predators, mean developmental time, oviposition period, and longevity were inversely related to temperature from 25 to 35 °C. Various parameters were studied for A. swirskii and N. cucumeris at 25 °C, 30 °C and 35 °C, i.e. the female developmental time, 9.37, 7.29, 5.56, and 10.67, 8.38, 6.45 d; oviposition period, 19.77, 16.18, 13.94 and 15.90, 13.84, 10.64 d; longevity, 29.39, 24.79, 20.64 and 25.42, 21.94, 17.39 d; fecundity, 31.91, 37.10, 42.16 and 21.75, 26.84, 30.56 eggs per female, respectively. The maximum daily predation rate for both the predators was recorded at 35 °C during the oviposition period. The total predation of A. swirskii and N. cucumeris female was 370.86, 387.54, 405.83, 232.14, 263.32, 248.85 preys at 25 °C, 30 °C and 35 °C respectively. The maximum reproduction rate of A. swirskii and N. cucumeris (3.02, 2.87 eggs/♀/day) was recorded at 35 °C while the minimum (2.00, 1.36 eggs/♀/day) was recorded at 25 °C. The life table parameters were estimated as net reproductive rate (Ro) 21.68, 25.94, 29.52 and 18.95, 20.25, 22.78; the mean generation time (T) 24.92, 21.82, 18.24 and 26.30, 23.60, 20.56 d; the intrinsic rate of increase (rm) 0.181, 0.232, 0.248 and 0.170, 0.185, 0.196; the finite rate of increase (λ) 1.365, 1.551, 1.706 and 1.126, 1.324, 1.428 for A. swirskii and N. cucumeris at 25 °C, 30 °C and 35 °C respectively. The results of this study suggested that the two phytoseiid species are promising biological control agents of O. afrasiaticus at a wide range of temperatures.

Oviposition patterns of primary lepidopteran defoliators in soybean and the impact on structured refuge recommendations.

BACKGROUND: Transgenic Bt technology in soybean, with plants expressing Cry1Ac, has been adopted as an insect pest management tool. It was first adopted in large areas of South America and Asia in 2013. The risk of resistance in target pests to this technology demands insect resistance management (IRM) programs. In Brazil, a structured refuge (area of non-Bt soybean) planted adjacent to the Bt soybean crop has been an important IRM recommendation, particularly for the primary lepidopteran defoliators Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae). The overall goal of this study was to validate IRM recommendations to Bt soybean. The objectives were to document the impact of soybean phenology, cultivar choice and non-Bt soybean defoliation on moth oviposition. In addition, a mark-release-recapture study estimated the dispersal capacity of these species. Five field experiments per species were performed for 3 years. RESULTS: Our results revealed an increase in A. gemmatalis and C. includens oviposition, respectively, on Bt plants as a consequence of the difference in plant growth stage at the time of oviposition. Defoliation of non-Bt plants significantly increased the oviposition preference of both moth species for Bt plants. The mark-release-recapture experiment indicated an average dispersal distance of ~300 m from the release point for A. gemmatalis, with maximum recapture at 1000 m. CONCLUSION: Overall, our findings emphasize the importance of planting synchronization of Bt soybean and the structured refuge. In addition, when operational aspects in large soybean areas challenge this recommendation, the priority should be for planting the refuge area first. This approach will minimize the impact of selective oviposition of A. gemmatalis and C. includens. © 2024 Society of Chemical Industry.

Thermo-physiological changes and reproductive investment in a liolaemid lizard at the extreme of the slow-fast continuum.

Gravid female lizards often experience reduced thermal preferences and impaired locomotor performance. These changes have been attributed to the physical burden of the clutch, but some authors have suggested that they may be due to physiological adjustments. We compared the thermal biology and locomotor performance of the lizard Liolaemus wiegmannii 1 week before and 1 week after oviposition. We found that gravid females had a thermal preference 1°C lower than that of non-gravid females. This was accompanied by a change in the thermal dependence of maximum running speed. The thermal optimum for locomotor performance was 2.6°C lower before oviposition than after. At relatively low temperatures (22 and 26°C), running speeds of females before oviposition were up to 31% higher than for females after oviposition. However, at temperatures above 26°C, females achieved similar maximum running speeds (∼1.5 m s-1) regardless of reproductive stage. The magnitude of the changes in thermal parameters and locomotor performance of L. wiegmannii females was independent of relative clutch mass (clutches weighed up to 89% of post-oviposition body mass). This suggests that the changes are not simply due to the clutch mass, but are also due to physiological adjustments. Liolaemus wiegmannii females simultaneously adjusted their own physiology in a short period in order to improve locomotor performance and allocated energy for embryonic development during late gravid stage. Our findings have implications for understanding the mechanisms underlying life histories of lizards on the fast extreme of the slow-fast continuum, where physiological exhaustion could play an important role.

Monitoring cotton squares with opened and/or yellowed bracts to determine the need and efficency of chemical control against the cotton boll weevil.

The technique of terrestrial sampling of boll weevil (BW) populations is expensive and inefficient over large areas, but may be cheaper and more efficient without involving the manipulation of cotton squares. The aim of this study was to develop a technique to sampling cotton squares based on the observation of opened and/or yellowing bracts to determine the need and efficacy of chemical control of BW in cotton crops. The first experiment aimed to estimate the ratio between the number of cotton squares with opened and/or yellowed bracts and that of squares with BW oviposition punctures. The second experiment, aimed to determine the efficacy of chemical control for BW by sampling cotton squares with opened and/or yellowed bracts. The ratio between the number of opened and/or yellowed bracts and the number of cotton squares with oviposition punctures was 2:1. The level and efficiency of chemical control of BW, based on the percentage and sampling of cotton plants with opened and/or yellowed bracts, was 5% and did not differ from the one based on the observation of cotton plants with 10% cotton squares with oviposition punctures by BW females. The control level based on sampling cotton plants with open and/or yellowing bracts was 5%. The efficiency of chemical insecticides using this economic threshold against the BW did not differ from that based on sampling cotton plants with 10% of cotton squares with oviposition punctures by BW females. This indicates that the chemical control of cotton boll weevil can be carried out based on cotton squares with open and/or yellowed bracts.

The impact of yeast-encapsulated orange oil in Aedes aegypti oviposition.

The yeast-encapsulated orange oil (YEOO) is a novel larvicide under development against vector mosquitoes. Despite its efficiency against Aedes aegypti (L.) in small scale experiments, its applicability in vector control can be influenced by other effects on mosquito behaviour or physiology. For this reason, the impact of YEOO particles in mosquito oviposition was evaluated in laboratory and semi-field conditions. Oviposition assays with one gravid Aedes aegypti female were carried under laboratory and semi-field conditions with natural light and temperature fluctuation. For all ovitraps, the number of eggs was manually counted in the wooden paddle and in the solution of each ovitrap. The proportion of eggs between substrates (wooden paddle and solution) varied between conditions, with females in laboratory presenting a lower preference to lay eggs in paddles when compared with studies in semi-field. This behaviour shifts in laboratory can create challenges to extrapolate results from laboratory to the field. Here, studies in both conditions indicate a similar impact of YEOO particles in Aedes aegypti oviposition. The potential treatment concentration of YEOO particles presents a strong repellent/deterrent effect (-0.559 > OAI > -0.760) within the initial 72h of application when compared with water, and weak repellent/deterrent signal (OAI = -0.220) when compared against inactivated yeast. Control ovitraps with water were more positive for egg presence than treated ovitraps, while ovitraps with YEOO particles and inactivated yeast present similar number of positive ovitraps. It is possible that the repellent/deterrent action is partially driven by the delivery system, since most times Citrus sinensis EO oviposition repellent/deterrent signal is weak, and it seem influenced by solvent/delivery used. However, it is unclear how the yeast wall that protect/surrounds the orange oil will negatively affect oviposition since live yeast are normally consider an attractant for mosquito oviposition.

[Dengue, chikungunya and the mosquito vector at the Southern limit of distribution during the 2023 epidemic, Argentina]. / Dengue, chikungunya y el mosquito vector en el límite sur de distribución durante la epidemia 2023, Argentina.

OBJECTIVES: To monitor the oviposition activity of the mosquito Aedes aegypti and of dengue and chikungunya cases in four localities of temperate Argentina, during the 2023 epidemic. METHODS: During the summer and autumn of 2023, the oviposition activity of the mosquito vector was monitored weekly using ovitraps, and the arrival of cases with dengue or chikungunya in Tandil, Olavarría, Bahía Blanca and Laprida were registered. RESULTS: Monthly variations of the percentage of positive traps were similar in the first three locations; in Laprida the mosquito was not detected. On the contrary, a significant difference was observed in the percentage of total traps that ever tested positive in each locality, being higher in Olavarría (83.3%) than in Bahía Blanca (68.6%) and Tandil (48.7%). Regarding diseases, 18 imported cases of dengue and 3 of chikungunya were registered. In addition, the first autochthonous case of dengue in the region was recorded, being the southernmost until known. CONCLUSION: It is essential to raise awareness and train the members of the health systems of the new regions exposed to Ae. aegypti for early detection of cases, and to the general population to enhance prevention actions.

OBJETIVOS: Monitorear la actividad de oviposición del mosquito Aedes aegypti y de casos de dengue y chikungunya en cuatro localidades de Argentina templada, durante la epidemia del 2023. Métodos: Durante el verano y otoño del 2023, se monitoreó semanalmente mediante ovitrampas la actividad de oviposición del mosquito vector, y se registró el arribo de casos con dengue o chikungunya a Tandil, Olavarría, Bahía Blanca y Laprida. RESULTADOS: La variación mensual del porcentaje de trampas positivas fue similar en las tres primeras localidades; en Laprida no se detectó el mosquito. Por el contrario, se observó una diferencia significativa del porcentaje de trampas que alguna vez resultó positiva en cada localidad, siendo mayor en Olavarría (83%), que en Bahía Blanca (67%) y Tandil (49%). Respecto a las enfermedades, se registraron 18 casos importados de dengue y 3 de chikungunya. Además, se registró el primer caso autóctono de dengue en la región, siendo el más austral hasta el momento. Conclusión: Es imprescindible sensibilizar y capacitar a los integrantes de los sistemas de salud de las nuevas regiones expuestas al Ae. aegypti para la detección temprana de casos, y a la población en general para potenciar las acciones de prevención.

Oviposition site selection and subsequent offspring performance of Aedes aegypti in short- and long-term detritus accumulation conditions.

The "oviposition preference-offspring performance" hypothesis proposes that females lay their eggs in habitats that maximize the fitness of their offspring. The aim of this study was to assess the oviposition site selection by Aedes aegypti females and the success of their larvae in habitats with different detritus accumulation times, under conditions representative of the natural spatial variability of detritus quality and quantity in the Metropolitan Area of Buenos Aires, Argentina. Two experiments were performed, one assessing oviposition site selection and the other analyzing developmental success. In both experiments, two levels of detritus accumulation time were compared, one with short-time detritus accumulation (2 weeks), and the other with long-time detritus accumulation (8 weeks). Naturally fallen detritus was used in both experiments, collected in ten sites across the Metropolitan Area of Buenos Aires. In the oviposition experiment, two contiguous ovitraps corresponding to each accumulation time were placed at each of the ten sites and the number of eggs received for each accumulation time was compared. In the development experiment, always 19 larvae were raised in containers of both accumulation times and overall performance was compared using an integrated index that considers survival, development time and female size. A large variability in the amount of detritus collected at the different sites was observed. The number of eggs was significantly higher in the long-time than in the short-time detritus accumulation containers, and approximately proportional to the amount of detritus in each ovitrap. The performance was not affected by the detritus accumulation time, but a better performance was detected in containers that received a higher amount of organic detritus, regardless of the accumulation time. Leaves were on average the most abundant type of detritus, with an average of 53 % of the total detritus collected. The amount of leaves added 2 weeks before hatching showed a positive effect on larval performance. Our results do not support the "oviposition preference-offspring performance" hypothesis, since Ae. aegypti females laid eggs in containers where larvae did not show a better performance. Moreover, at larval densities related to the number of eggs actually laid in each of the accumulation times, it is expected that the performance would be even worse in the most selected containers, due to the density-dependent effects of crowding. Since the results obtained reflect the natural heterogeneity of the environmental conditions in the region studied, they might be a fairly good indicator of what occurs in natural larval habitats.

Bionomics, reproductive traits and assessment of forensic relevance of Peckia (Peckia) chrysostoma (Wiedemann, 1830) (Diptera: Sarcophagidae).

Peckia (Peckia) chrysostoma (Wiedemann, 1830) (Diptera: Sarcophagidae) is a colonizer of cadavers in the Neotropical Region. Nevertheless, data on development for the P. (P.) chrysostoma (e.g., instar duration) and behavioral strategies used by the species for locating and colonizing a corpse are scant. We aimed to explore bionomic and reproductive aspects of the flesh fly P. (P.) chrysostoma, and in this article we: (a) provide quantitative data on the life cycle of P. (P.) chrysostoma; (b) present bionomic measurements (length and weight) of larvae and pupae; (c) describe intrauterine egg and larvae development; and (d) analyze the ovo/larviposition behavior by gravid females. Females showed ovaries with discernible eggs and larvae between 8 and 10 days (x̅ = 23.3 eggs/female). This study reports the first observation of egg deposition, an atypical behavior for the species. The average development time for immature stages was 22.24 h and 21.36 h for 1st and 2nd respectively, and 3rd showed an average development time of 80.47 h. Pupa had the longest duration (x̅ = 295.69 h). A direct increase was observed in weight (P < 0.05) and length (P < 0.05) throughout time. The average survival time of males and females is approximately 30 days. This study expands the knowledge on P. (P.) chrysostoma, such as facultative ovoviviparity under laboratory conditions and the life cycle, which may benefit future studies for accuracy in entomology-based estimation of minimum post-mortem interval (min PMI).

Alpha- and beta-pinene isomers act differently to control Rhipicephalus microplus (Acari: Ixodidae).

The cattle tick Rhipicephalus microplus is an ectoparasite of high importance in veterinary medicine and public health. Since synthetic chemicals used to control these ticks can select resistant strains and cause toxic effects in their hosts, there is a need to identify effective substances with fewer adverse effects. For this reason, we investigated the effects of alpha- and beta-pinene, known for their various biological effects, on the mortality and reproductive performance of R. microplus engorged female ticks. The products were diluted in a 2% Tween 80 aqueous solution. The ticks were first weighed and then immersed in the test solutions for five minutes. Then, they were dried with paper towels and fixed dorsoventrally in Petri dishes, totalling five treatment groups for each pinene and a control group treated with the solvent alone. The ticks were monitored daily for mortality, and their eggs were collected and weighed. The larval hatching rate was estimated, and the pre-oviposition and incubation periods were determined. From these data, the following parameters were calculated: egg production index, fertility rate, estimated reproduction rate, percentages of reduction in oviposition and hatching, and product efficacy. Alpha-pinene showed better results at higher concentrations, unlike beta-pinene, which was more effective at lower concentrations. The effectiveness of alpha-pinene was 74% at a concentration of 14.0 µL/mL, while beta-pinene showed 78% efficacy at 2.0 µL/mL. The results indicated for the first time different effects of two isomers in ticks, suggesting that these compounds act on R. microplus females in different ways.

New artificial hematophagy system with attractive polymeric biofilm for maintenance of Culex quinquefasciatus (Diptera: Culicidae) in the laboratory.

BACKGROUND: Maintaining mosquito colonies in the laboratory requires a blood supply so that females' oocytes can mature and oviposition can take place. In this study, a new artificial hematophagy system for colonization and maintenance of Culex quinquefasciatus in the laboratory was developed and tested. METHODS: We developed an attractive polymeric biofilm including 25% L-lactic acid for use as a membrane in an artificial hematophagy system and compared the feeding rate of females with Parafilm-M®. We also evaluated the oviposition rate, larval survival and adult emergence of females fed through the attractive biofilm. RESULTS: The average percentage of female Cx. quinquefasciatus fed through the attractive biofilm was 87%, while only 20% became engorged with Parafilm-M® (p < 0.0001). Feeding through the attractive biofilm developed in this study produced high levels of evaluated biological parameters; the percentage of egg laying by females that underwent artificial hematophagy through the biofilm was 90%, with an average of 158 eggs per raft. From these eggs, 97% of the larvae hatched, of which 95% reached the pupal stage. The adult emergence rate corresponded to 93% of pupae. CONCLUSIONS: Insects fed with attractant through the biofilm system had a higher engorgement rate compared to those fed through Parafilm-M®. Our study is preliminary and suggests that polymeric biofilm has great potential for artificially feeding mosquitoes in the laboratory. Based on this research, new studies will be carried out with biofilm and different systems.