Pre-reproductive Period Research Articles

Biology of mustard aphid, Lipaphis erysimi on Brassica juncea genotype RH 725 in semi-arid zone of Haryana, India

Mustard aphid, Lipaphis erysimi (Kaltenbach) is one of the major insects of Indian mustard. It damages the various part of mustard plant as a result crop yield and oil content reduced. Scanning of the literature showed that no researcher had worked on all the parameters of biology of this insect on any crop. No work found regarding biology of mustard aphid on genotype RH 725. Therefore, on the basis of this fact studies on biology of mustard aphid was carried out during 2019-20 at Farmer’s field, Kolana village, Aravalli Hills Region, Rewari, Haryana, India. The results of the studies revealed that mustard aphid passed through four nymphal instars before attaining the adult stage. The average length of first, second, third and fourth instar nymph was 0.74 ± 0.07, 0.89 ± 0.06, 1.14 ± 0.14 and 1.31 ± 0.13 mm, respectively. The average width was 0.40 ± 0.04, 0.48 ± 0.03, 0.60 ± 0.06 and 0.72 ± 0.09 mm, respectively. The average length of apterate adult female was 1.62 ± 0.14 mm and width 0.94 ± 0.07 mm. The average duration of instars was 1.33 ± 0.37 (1st), 1.44 ± 0.38 (2nd), 1.79 ± 0.72 (3rd) and 2.14 ± 0.61 days of 4th instar. The average total nymphal instars period was 6.69 ± 1.11 days. The average longevity of adult recorded as 7.41 ± 1.61 days. The average pre-reproductive, reproductive and postreproductive period was 0.98 ± 0.47, 5.85 ± 1.58 and 0.57 ± 0.68 days, respectively. The average fecundity of an adult female was 24.63 ± 9.88 and birth rate was 4.12 ± 0.77 nymphs, whereas average total life span was 14.02 ± 2.21 days. This study provides important life history information of mustard aphid which may help to develop suitable integrated pest management strategies for this pest.

Asymmetric Interaction between Aphis spiraecola and Toxoptera citricida on Sweet Orange Induced by Pre-Infestation.

Indirect interactions between herbivorous insects that share the same host have been focused on insects feeding on herbaceous plants, while few studies investigate similar interactions on woody plants. We investigated performance and feeding behavior of two citrus aphids, Aphis spiraecola Patch and Toxoptera citricida Kirkaldy, on sweet orange as affected by prior infestation of conspecifics and heterospecifics. Results showed that pre-infestation-induced interactions between A. spiraecola and T. citricida were asymmetric, with A. spiraecola gaining more fitness. In detail, pre-infestation by A. spiraecola decreased adult weight, enhanced survival rate and accelerated phloem sap acceptance of conspecifics. However, A. spiraecola pre-infestation did not affect performance or feeding behavior of T. citricida. In another infestation sequence, the pre-infestation of T. citricida did not affect conspecifics, but positively affected heterospecifics, indicated as a decreased pre-reproductive period, enhanced survival rate, adult weight, fecundity, and feeding efficiency, i.e., faster access and acceptance of phloem sap, and longer phloem sap ingestion duration. Furthermore, we found A. spiraecola pre-infestation enhanced amino acid concentration, amino acid to sugar ratio, activated salicylic acid and jasmonic acid marker gene expression, while T. citricida pre-infestation only depressed jasmonic acid marker gene expression. Changes in nutrient and phytohormone-dependent defense probably underlie the asymmetric effect.

Major Transitions in Cuticular Hydrocarbon Expression Coincide with Sexual Maturity in a Blowfly (Diptera: Calliphoridae).

In many animals, there is a prolonged pre-reproductive period prior to sexual maturity. To avoid premature mating attempts, it is common for phenotypic changes to occur during this period that signal the onset of reproductive viability. Among the insects, pre-reproductive phases can last for up to 50% of the adult lifespan, but little is known about the accompanying phenotypic changes that signal sexual maturity. Contact pheromones such as cuticular hydrocarbons (CHCs) may fulfil this role, as they are known to change rapidly with age in many insects. Despite this, few studies have investigated CHC development in the context of sexual maturity or considered differences in CHC development between sexes. The blowflies (Diptera: Calliphoridae) provide an ideal system for such studies because CHCs are known to change rapidly with age and likely play an important role in sexual behaviour. As such, using the small hairy maggot blowfly Chrysomya varipes, we investigate whether there are age- and sex-specific changes in CHCs over the course of adult blowfly maturation. We show that: (1) major qualitative transitions in CHC expression coincide with the onset of sexual maturity and (2) these changes occur more slowly in females - in line with their extended pre-reproductive phase. We suggest that CHCs may play an important role in signalling sexual maturity in the small hairy maggot blowfly and that this species will likely serve as a useful model for understanding the complex ontogeny of cuticular hydrocarbons in insects.

Limb-Bone Development of Seymouriamorphs: Implications for the Evolution of Growth Strategy in Stem Amniotes

Tetrapod life on land was the result of a lengthy process, the final steps of which resulted in full independence of amniotic tetrapods from the aquatic environment. Developmental strategies, including growth rate and the attainment of sexual maturity, played a major role in this transition. Early amniotes, such as Ophiacodon, tended to reach sexual maturity in a year while most non-amniotic Paleozoic tetrapods (including Devonian tetrapods and temnospondyls) became adult after 3 to 11 years. This ontogenetic transition is accompanied by a drastic change in growth rate and bone microstructure suggesting faster growth dynamics in early amniotes than in Devonian tetrapods and temnospondyls. Was the acquisition of a faster development (earlier sexual maturity and faster growth rate) a drastic evolutionary event or an extended process over geological time? To answer this question, the limb bone histology of two Early Permian (i.e. 270-290 million-year-old) stem-amniote seymouriamorphs, Seymouria sanjuanensis and Discosauriscus austriacus, were investigated. We used three-dimensional bone paleohistology based on propagation phase-contrast synchrotron microtomography. Both seymouriamorphs display relatively fast bone growth and dynamics (even though cyclic in the humerus of D. austriacus). This significantly contrasts with the slow primary bone deposition encountered in the stylopods of temnospondyls and Devonian (i.e. 360 million-year-old) stem tetrapods of similar sizes. On the basis of skeletochronological data, the seymouriamorph D. austriacus retained a long pre-reproductive period as observed in Devonian tetrapods and most temnospondyls. The combination of characteristics (faster growth rate but long pre-reproductive period) suggests that the shift towards an amniotic developmental strategy was an extended process in the evolutionary history of amniotes.

Effects of delayed mating on male mating success and female reproductive performance of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

Phenacoccus solenopsis is a devastating pest of cotton. It causes significance losses in cotton crops in China, India and Pakistan. Recently, chemical control is best tool for its management but delayed mating effects and pheromone-mediated disruption technique is still unknown. In this experiment, we study effects of male-only, female-only and both sexes delayed mating on mating success, reproduction and longevity of P. solenopsis. Effects of male-only and female-only delayed mating was assessed by pairing of different hours old males with 13-days old females and different days old females with 2-h-old males, respectively. Results showed that male-only delayed mating increased the female prereproduction period and male longevity, reduced the oviposition period, fecundity and mating success, and did not affect the preoviposition period and female longevity. Conversely, female-only delayed mating did not change the male mating success and male longevity. Female-only delayed mating gradually decrease the prereproductive period and continuously increase preoviposition period and longevity. Oviposition period did not change until age exceeded 34 days, and fecundity remained constant until age exceeded 26 days in female-only delay mating. Both sexes delayed mating reduced the fecundity, mating success, prereproduction and oviposition period, but greatly increased the preoviposition period and male and female longevities. These results suggest that mating disruption techniques, such as application of sex pheromones, will be very useful for the management of P. solenopsis under the field level either applying alone or using with integrated pest management tools.

Trade-offs between host tolerances to different pathogens in plant-virus interactions.

Although accumulating evidence indicates that tolerance is a plant defence strategy against pathogens as widespread as resistance, how plants evolve tolerance is poorly understood. Theory predicts that hosts will evolve to maximize tolerance or resistance, but not both. Remarkably, most experimental works failed in finding this trade-off. We tested the hypothesis that the evolution of tolerance to one virus is traded-off against tolerance to others, rather than against resistance and identified the associated mechanisms. To do so, we challenged eighteen Arabidopsis thaliana genotypes with Turnip mosaic virus (TuMV) and Cucumber mosaic virus (CMV). We characterized plant life-history trait modifications associated with reduced effects of TuMV and CMV on plant seed production (fecundity tolerance) and life period (mortality tolerance), both measured as a norm of reaction across viral loads (range tolerance). Also, we analysed resistance-tolerance and tolerance-tolerance trade-offs. Results indicate that tolerance to TuMV is associated with changes in the length of the pre-reproductive and reproductive periods, and tolerance to CMV with resource reallocation from growth to reproduction; and that tolerance to TuMV is traded-off against tolerance to CMV in a virulence-dependent manner. Thus, this work provides novel insights on the mechanisms of plant tolerance and highlights the importance of considering the combined effect of different pathogens to understand how plant defences evolve.

Biological aspects and feeding behavior of cotton aphid in watermelon cultivars submitted to silicon application

ABSTRACT This research aimed to evaluate the biological aspects and the feeding behavior of Aphis gossypii in watermelon cultivars submitted to silicon application. The experiment was conducted at the Institute of Education, Agriculture and Environment of the Federal University of Amazonas, Humaitá, Brazil. The experimental design was completely randomized in a 2×3 factorial (with and without silicon; cultivars Crimson Sweet, Fairfax and Charleston), with ten replications. The application of silicic acid (1%) was carried out directly on the substrate using dose equivalent to 1 ton SiO2·ha-1, 25 days after sowing. The rearing of aphids was kept in cucumber plants, cultivar Caipira. Insect biology tests were conducted to evaluate the duration of the prereproductive, reproductive and postreproductive periods, longevity, number of nymphs, and feeding behavior using the honeydew secretion technique. Analysis of variance was performed using the statistical program SISVAR and the means were compared by the F and Scott–Knott test (p ≤ 0.05). The silicon application to watermelon plants affects the reproduction and feeding of A. gossypii. The watermelon plants cultivar Crimson Sweet treated with silicon has high resistance to feeding by A. gossypii.

The Impact of Sorghum Growth Stage and Resistance on Life History of Sugarcane Aphids (Hemiptera: Aphididae).

Recent invasion of a new haplotype of sugarcane aphid (Melanaphis sacchari Zehntner) resulted in severe outbreaks of the aphids in sorghum (Sorghum bicolor L. Moench [Poales: Poaceae]) across the United States. Previous research and field observations suggested that both sorghum resistance and growth stage were important to their population dynamics in the field and hence effective and timely management to minimize economic losses associated with this pest. To explore this, we designed greenhouse experiments to quantify fecundity, prereproductive period, and longevity of sugarcane aphids across several vegetative and reproductive growth stages of a resistant (DKS 37-07) and susceptible (M77GB52 and DKS 38-88) sorghum hybrids commonly used in sorghum production. We found significant effects of sorghum resistance and growth stage on several life history traits and demographics parameters of sugarcane aphids. We did not, however, note any significant interactive effects of resistance and phenology on any of the response variables. Sugarcane aphids exposed to the susceptible sorghum produced significantly more offspring, had significantly greater intrinsic and finite rates of increase, and significantly shorter population doubling time than the aphids feeding on resistant sorghum. On the other hand, the impact of sorghum growth stage had more variable effects on life history of sugarcane aphids that were most frequently evident at the late reproductive stages. These outcomes support our hypothesis that sorghum in late stages of growth tends to be a better host for sugarcane aphids and highlight the importance of sorghum growth stage to sugarcane aphid life history and population growth potential.

Effects of Five Host Plant Species on the Life History and Population Growth Parameters of Myzus persicae (Hemiptera: Aphididae).

The green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae), is an important agricultural pest with a wide range of host plants. To study effects of host species on the life history traits of M. persicae, aphids were individually reared on five host plants: Brassica campestris L. (Brassicales: Brassicaceae), Capsicum annuum L. (Tubiflorae: Solanaceae), Nicotiana tabacum L. (Tubiflorae: Solanaceae), Raphanus sativus L. (Brassicales: Brassicaceae), and Vicia faba L. (Rosales: Leguminosae). TWOSEX-MSchart software was used for the statistical analysis according to the age-stage, two-sex life table theory. The results showed that the shortest preadult stage and adult/total prereproductive period of M. persicae were 6.48, 0.19, and 6.67 d on V. faba, respectively. While the adult and total longevity of M. persicae on R. sativus (25.00 and 31.62 d) and N. tabacum (24.40 and 30.56 d) were significantly longer than that on the other three hosts, as was the reproductive period. The fecundity of M. persicae on R. sativus (80.83 nymphs per female), N. tabacum (71.72 nymphs per female), and V. faba (70.39 nymphs per female) was also greater than that on B. campestris and C. annuum. It was demonstrated that V. faba, R. sativus, and N. tabacum were more suitable plants for the growth of M. persicae exhibiting a shorter preadult stage, longer longevity, and greater fecundity than the remaining two species, as confirmed by the higher intrinsic rate of increase and net reproductive rate.

Accelerated Sexual Maturation in Methoprene-Treated Sterile and Fertile Male Queensland Fruit Flies (Diptera: Tephritidae), and Mosquito Larvicide as an Economical and Effective Source of Methoprene.

Queensland fruit flies Bactrocera tryoni ('Q-fly') have long adult prereproductive development periods, which can present challenges for sterile insect technique (SIT) programs. Holding the sterile flies in release facilities is expensive for control programs. Alternatively, releases of sexually immature males can lead to substantial mortality of sterile males before they mature. Recent studies have reported effectiveness of dietary supplementation with a mosquito larvicide (NOMOZ) that contains S-methoprene, a juvenile hormone analogue, for accelerating sexual development of fertile Q-fly males. However, it is not known whether effects on sterile flies are comparable to effects on fertile flies, or whether effects of methoprene-containing larvicide are comparable to effects of analytical standard methoprene such has been used in most studies. Here we address both knowledge gaps, investigating the effects of analytical standard methoprene and NOMOZ mixed with food and provided for 48 h following emergence on sexual development and longevity of fertile and sterile Q-flies. Compared with controls, fertile and sterile male Q-flies that were provided diets supplemented with methoprene from either source exhibited substantially accelerated sexual development by 2-3 d and longer mating duration. Unlike males, females did not respond to methoprene treatment. Although fertile and sterile flies were generally similar in sexual development and response to methoprene treatment, sterile flies of both sexes tended to have shorter copula duration than fertile flies. Neither methoprene supplements nor sterilization affected longevity of flies. The present study confirms effectiveness of dietary methoprene supplements in accelerating sexual development of both fertile and sterile male (but not female) Q-flies, and also confirms that low-cost mosquito larvicides that contain methoprene can achieve effects similar to those for high-cost analytical grade methoprene as prerelease supplements for Q-fly SIT.

Optimizing cold storage of the ectoparasitic mite Pyemotes zhonghuajia (Acari: Pyemotidae), an efficient biological control agent of stem borers.

Pyemotes zhonghuajia Yu, Zhang and He is a newly discovered native ectoparasitic mite that efficiently controls stem borers in China. To provide a steady and sufficient supply, extend adult lifespan and synchronize field augmentative releases of P. zhonghuajia, we determined the optimal cold storage temperature and duration by storing 1-day-old mated females at 8, 10 and 12°C for 10-90days with a 10-day interval in the laboratory. We then recorded mite survival during storage and monitored the post-storage reproductive performance of mites at a control temperature of 25°C. We found that all mites survived at 10 and 12°C for different durations, but mortality occurred when mites were stored at 8°C for ≥ 30days with more than 70% of mites dead when the storage duration prolonged up to 50days. The proportion of reproductive females was higher at 10°C but decreased with the prolonged storage duration at all test temperatures. Storage temperature had no significant effect on the pre-reproductive period and offspring sex ratio, whereas prolonged storage induced longer pre-reproductive period and lower proportion of female offspring. The reproductive period increased with increasing storage temperature and with prolonged storage up to 50 and 60days; however, the longer reproductive period did not directly translate into greater reproductive output. We found that compared with the control, mites stored at 10°C for up to 30days did not significantly reduce their survival, proportion of reproductive success and number and sex ratio of offspring, suggesting that 10°C and ≤ 30days were the optimal cold storage temperature and duration, respectively, for post-mass production storage before the field augmentative release of P. zhonghuajia.

Resistência induzida ao pulgão-do-algodoeiro em cultivares de algodão colorido

The aim of this study was to evaluate the resistance induced by chemical inducers on cultivars of colored cotton. The cotton was planted in pots and kept in a climate-controlled room (28±2oC daytime temperature, 25±2oC night temperature, 70±10 % R.H.; and 12 hours of photoperiod). Silicon and acibenzolar-S-methyl were applied to the plants that were offered to Aphis gossypii afterwards. The bioassays were conducted in a randomized design in a factorial arrangement, with three cultivars of cotton and two resistance inducers, with ten repetitions. The biological parameters observed were: ninfal mortality, duration of nymphal stage, and pre-reproductive, reproductive and post-reproductive periods, longevity and total number of nymphs produced. The lignin and phenol content in the leaves were quantified. The longest duration of the nymphal period, the lower number of nymphs produced, and the major mortality were observed in the ASM treatment. Silicon and ASM promoted an increase in lignin content in the cv. BRS Verde. Thus, the ASM application affected negatively biological parameters of A. gossypii, by increasing the lignin content in plants. The cv. BRS Verde is a better cutivar to be used, because it accumulated higher lignina and phenol contents.

Evaluation of Steroid Sex Hormone Levels in Cockatiels During Their Reproductive Cycle

Sexual steroid hormone concentrations differ with respect to the different stages of animal life. For example, hormone concentrations in the reproductive stage show a periodic variation. Studies on variations in sexual hormones in parrots using non-invasive methods as well as the effect of nest-boxes in parrots are less. This study aimed to detect the levels of fecal steroid hormones during the cockatiel reproductive cycle and to investigate the effect of nest-box placement on reproduction. There were 24 mating pairs of cockatiels, and the study was conducted over 13 months. Based on their reproductive status, individual birds were divided into pre-reproduction (PR), incubation (IN), and parent period (PA) in the pre-test; then, the nest box was either temporarily removed for 20 days (RN) or continuously provided (pre-reproduction, PR). The estrogen concentrations measured in the last stage of the PR period and the initial stage of the IN period were significantly higher than those measured in the PA stage, and there were no significant differences in testosterone and progesterone concentrations throughout the reproductive cycle. The nest-box treatments (NB) indicated that eggs were laid 6-13 days after the new box was hung; however, in the pre-test, there was an interval of 30-40 days before the next mating pairs started the next reproductive stage or no reproduction. Estrogen concentrations in PR and testosterone concentrations in RN were significantly higher than those in the other periods during the nest-box treatments. In conclusion, estrogen showed the most significant change among the fecal steroid hormones measured. Nest boxes serve as a positive stimulus for parrot reproduction management and can help non-seasonal reproductive parrots to rapidly enter the next breeding cycle.

Transgenerational hormetic effects of sublethal dose of flupyradifurone on the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae).

Both inhibitory and stimulatory (known as hormesis) effects of the sublethal flupyradifurone, a butenolide insecticide, on Myzus persicae Sulzer (Hemiptera: Aphididae) were investigated for incorporating it into integrated pest management (IPM). A leaf-dip bioassay showed that flupyradifurone was very toxic against adult M. persicae with a 48 h LC50 of 8.491 mg/L. Using the age-stage two-sex life table approach, we assessed the effects of LC25 of flupyradifurone on adult M. persicae and its progeny (F1 and F2). On the one hand, aphids exposed to flupyradifurone had significantly negative effects on the life history traits acrossing the generations, such as reduced the adult longevity and fecundity of F0, shortened the duration of third instar and fourth instar nymphs, preadult period and the pre-reproductive period of F1, and decreased the reproductive days and adult longevity of F2. On the other hand, stimulatory effects on the duration of pre-adult, adult reproductive days, and reproduction of F1 were observed in the flupyradifurone-treated aphids. Consistently with the stimulation on individual traits, a higher net reproductive rate (R0) of F1 and a shorter mean generation time (T) of F2 were observed in the flupyradifurone-treated aphids, although the other population parameters including the intrinsic rate of increase (r), finite rate of increase (λ) and T of F1 and R0, r and λ of F2 were not significantly affected. These results revealed that adult M. persicae exposed to sublethal concentration of flupyradifurone can induce hormetic effects on F1, and also cause negative effects on F2. Our results would be useful for assessing the overall effects of flupyradifurone on M. persicae and the hormetic effects should take into consideration when use flupyradifurone for control M. persicae.

Quantifying site and species factors to inform the feasibility of eradication of alien plants from Southern Ocean Islands: Stellaria media on Macquarie Island

Eradication of alien plants is notoriously challenging, however eradication projects reap great biodiversity benefits, particularly on islands. To date only individual plants or small restricted populations have been successfully eradicated from the Southern Ocean Islands (SOI). The next phase in conservation for the region is tackling more widespread, abundant alien plant species. Several on-going and proposed control programs for such weeds exist in the SOI and Antarctic regions. If eradication of a widespread species is to be successful, a number of factors need to be considered. ‘Organisational’ factors such as management agency capacity, resources and the availability of effective control methods are critical to the success of an eradication. ‘Site and species’ factors such as infestation extent, number of discrete populations, dispersal processes and detectability typically show a cumulative effect on success. We assessed the site and species factors for Stellaria media, an alien species on sub-Antarctic Macquarie Island, to determine the feasibility of its eradication from the island. Organisational factors can successfully be met with adequate funding. Site and species factors which reduce the likelihood of eradication included large gross infestation areas, large plants with high reproductive output (precocity or fecundity), dense seed banks, short pre-reproductive period, extended seed longevity and vegetative reproductive capacity. We recommend a small-scale eradication trial for restricted, easily accessible populations of S. media on Macquarie Island to further evaluate the likelihood of broader eradication.

Thermal requirements, life expectancy and fertility tables of Aphis craccivora (Hemiptera: Aphididae) in Vigna unguiculata (Fabales: Fabaceae) under laboratory conditions

ABSTRACT: The objective of this research was to determine the thermal requirements and develop life expectancy and fertility tables of Aphis craccivora (L.) in Vigna unguiculata (Walp.). The insects were kept in Petri dishes and fed V. unguiculata leaf discs (cultivar BRS-Tumucumaque) under five constant temperatures (18, 22, 25, 28 and 31ºC). Live and dead insects and stages of development; the onset and duration of the pre-reproductive, reproductive and post-reproductive periods; the number of nymphs per female; and the longevity of the adults were quantified daily. Based on these observations, fertility life expectancy tables were developed, and the thermal requirements of the cowpea black-aphid were determined. Increased temperature influenced all stages of insect development, as well as the pre-reproductive and post-reproductive periods and the total number of nymphs per female. The base temperature for development was 9.13ºC with thermal development constant of 99.0 GD. The highest net reproduction rate (Ro) was at 25ºC. At 28ºC, the greatest capacity to increase in number (rm) was observed, as well as the highest finite rate of increase (λ) and the shortest time to double in number (TD). The thermal range between 22 and 28ºC can be considered most favourable to the development of A. craccivora in V. unguiculata. Temperatures below 22 and above 28ºC affect the fertility and survival of cowpea black-aphids. Increased temperature induces reproduction and reduces the longevity and life expectancy of A. craccivora in cowpeas.

Aromatase immunolocalization and activity in the lizard's brain: Dynamic changes during the reproductive cycle

The purpose of the present study is to highlight the role of aromatase in the neuroendocrine control of the reproductive cycle of the male lizard Podarcis sicula during the three significant phases, i.e. the pre-reproductive, reproductive, and post-reproductive stages. Using immunohistochemical, biochemical, and hormonal tools, we have determined the localization and the activity of P450 aromatase (P450 aro) in the lizard's brain together with the determination of hormonal profile of sex steroids, i.e. testosterone and 17β-estradiol. The present data demonstrated that the localization of P450 is shown in brain regions involved in the regulation of the reproductive behavior (medial septum, preoptic area, and hypothalamus). Its activity, as well as the intensity of the signal, is modified according to the period of reproduction, resulting in functional dynamic changes. P450 aro activity and signal intensity decrease in the pre-reproductive period and progressively increase during the reproductive stage until it reaches the maximum peak level at the post-reproductive phase. P450 aro determines a local estrogen synthesis, balancing the testosterone and estradiol levels, and therefore its role is crucial, since it plays an important role in the neuroendocrine/behavioral regulation of the reproductive processes in the male lizard P. sicula.

Toxicity and Sublethal Effects of Flupyradifurone, a Novel Butenolide Insecticide, on the Development and Fecundity of Aphis gossypii (Hemiptera: Aphididae).

The cosmopolitan pest Aphis gossypii (Glover) causes considerable economic losses on various crops by its feeding damage and transmitting diseases around the world. Flupyradifurone is a novel butenolide pesticide; its toxicity on A. gossypii parent generation (F0) was estimated following treatment with LC25 concentration for 48 h. The adult longevity and fecundity of the F0 individuals treated by flupyradifurone showed no significant decrease in comparison with the control. Life table method was used to evaluate the sublethal effects on progeny population (F1). Results showed that the development time of the fourth instar and the preadult as well as the total pre-reproductive period were significantly prolonged, while their fecundity was significantly decreased compared with the control. Additionally, the intrinsic rate of increase (r), the finite rate of increase (λ), and the net reproductive rate (R0) of F1 were all significantly lower in the group treated by LC25 than in the control group. These results reveal that the sublethal concentration of flupyradifurone could suppress the population growth of A. gossypii and indicate that this novel insecticide may be as a useful tool in pest management.

Behavioral and biological responses of black bean aphid (Aphis fabae, Scopoli, 1763) on seven Algerian local broad bean cultivars

We studied the behavioral and biological parameters of Aphis fabae (Homoptera: Aphididae, Scopoli, 1763) on seven local Vicia faba L. cultivars. The antixenosis was conducted under laboratory controlled conditions of the temperature, light regime and relative humidity (18 ± 0.25 °C; L16: D8; 37.5 ± 0.6 %) for test in light, and (19 °C; 42 % relative humidity) for test in dark. The least preferred host plants for attractivity was the cultivar 141 in both tests while the cultivar 145 was the most preferred in light test, and the cultivar 107 in dark test. The antibiotic experiment was conducted also under laboratory conditions (L16: D8 photoperiod, 17 ± 1 °C, and 43.5 ± 5 % r. h.). Antibiosis was determined by studying the pre-reproductive period, reproductive period, adult longevity, survival, daily and total fecundity. The analysis of variance indicated that no significant differences on pre-reproductive period and daily fecundity of the A. fabae among the cultivars. However, the longest times of reproductive period, adult longevity, and survival were recorded on cultivar 135 followed by cultivar 141. The highest (85.8) and the lowest (15.8) number of progeny were observed on 135 and 141 cultivars, respectively.

First Report on Life History Parameters of Thripsaphis ballii (Gillette) on Shoreline Sedge (Cyperaceae) in Oklahoma Wetlands

Thripsaphis ballii (Gillette) aphids were first collected on Carex hyalinolepis Steudel plants in a restored wetland along the Deep Fork River in Lincoln County, OK, in 2015. Little is known about the species. A controlled study documented selected life history parameters at 28°C. T. ballii developed through four nymphal instars before the last molt into an adult. Total nymph development averaged 10.6 days, and average duration of each instar ranged from 2.38–2.88 days with more time spent as first and fourth instars. Mean pre-reproductive period for adults was 0.9 day, while reproductive period averaged 11.2 days in which females produced an average of 19.4 nymphs. Longevity (birth to adult) averaged 22.6 days. First and second instars had five antennal segments and third instars through adults had six segments. Based on morphological measurements, second through fourth instars and adults can be discerned based on a combination of body length, number of antennal segments, and antennal length. Information from the study provides the first recorded life history parameters for the species, as well as the first documentation of its occurrence in Oklahoma.