Female Longevity Research Articles

Developing the radiation-based sterile insect technique (SIT) for controlling Aedes aegypti: identification of a sterilizing dose.

The sterile insect technique (SIT) is emerging as a tool to supplement traditional pesticide-based control of Aedes aegypti, a prominent mosquito vector of microbes that has increased the global burden of human morbidity and mortality over the past 50 years. SIT relies on rearing, sterilizing and releasing large numbers of male mosquitoes that will mate with fertile wild females, thus reducing production of offspring from the target population. In this study, we investigated the effects of ionizing radiation (gamma) on male and female survival, longevity, mating behavior, and sterility of Ae.aegypti in a dose-response design. This work is a first step towards developing an operational SIT field suppression program against Ae.aegypti in St. Augustine, Florida, USA. Exposing late-stage pupae to 50 Gy of radiation yielded 99% male sterility while maintaining similar survival of pupae to adult emergence, adult longevity and male mating competitiveness compared to unirradiated males. Females were completely sterilized at 30 Gy, and when females were dosed with 50 Gy, they had a lower incidence of blood-feeding than unirradiated females. Our work suggests that an ionizing radiation dose of 50 Gy should be used for future development of operational SIT in our program area because at this dose males are 99% sterile while maintaining mating competitiveness against unirradiated males. Furthermore, females that might be accidentally released with sterile males as a result of errors in sex sorting also are sterile and less likely to blood-feed than unirradiated females at our 50 Gy dose. © 2022 Society of Chemical Industry.

Families in Transition: Four Prominent Irish Families Abandon the ‘Inward Light’

This article follows the association and membership of four families of similar socio-economic status, through seven generations, with Irish Friends over a period of slightly more than 200 years, to around 1900. Using historical data, a model has been presented to explain the key elements of their respective journeys through recruitment, engagement, and eventual abandonment of the Religious Society of Friends. The model had been supplemented with the results of a quantitative analysis of data related to membership and with generation as the principal cohort. Aspects considered included male and female longevity of membership, rates of membership attrition, child mortality and children’s contribution to membership, and an attempt to determine whether social mobility and occupational status contributed, in some measure, to declining rates of membership.The results of the quantitative analysis were much in accord with the model; each family, while journeying towards the same destination, progressed slightly differently but with some common characteristics. Child mortality was high in all four families as were rates of membership attrition, and females tended, on average, to have longer longevity of membership than men. And while social mobility was limited, all the families managed to consolidate their positions in middle-class society, many members comfortable with respectable titles in what became known as the Irish ‘Squirearchy’. By that time Friends had become a distant memory. It remains to be seen whether the model proposed here is applicable to Quaker families that belonged to other socio-economic denominations.This article was published open access under a CC BY licence: https://creativecommons.org/licences/by/4.0.

Effects of Elevated CO2 on the Fitness Parameters of Individually- and Group-Reared Agasicles hygrophila (Coleoptera: Chrysomelidae).

Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae) is a natural enemy of Alternanthera philoxeroides (Mart.) Griseb (Amaranthaceae: Alternanthera), a worldwide invasive weed. Elevated atmospheric CO2 concentrations may have significant impacts plants, herbivorous insects, and natural enemies. To assess the concurrent effect of elevated CO2 on the development time, fecundity, and population parameters of A. hygrophila, the age-stage, two-sex life table was used to understand the fitness and population parameters of individually-reared and group-reared A. hygrophila under elevated CO2 concentration. In individually-reared population, the development time of preadults, adult pre-oviposition period, and total pre-oviposition period of A. hygrophila in the elevated CO2 (eCO2, 750 ppm) treatment were shorter than those in the ambient CO2 (aCO2, 420 ppm) treatment. In group-reared population, the developmental time of preadults, female adult longevity, female proportion, adult pre-oviposition period, and total pre-oviposition period of A. hygrophila in eCO2 were longer than those in aCO2. Additionally, in both individually-reared and group-reared population, fecundity and oviposition days of A. hygrophila in eCO2 were higher than those in aCO2, and a higher intrinsic rate of increase, finite rate of increase, and the net reproductive rate of A. hygrophila were observed at eCO2. Moreover, shorter preadult development time, adult pre-oviposition period, total pre-oviposition period, male adult longevity, and higher fecundity were found in group-reared cohort at both aCO2 and eCO2. The results indicates that elevated CO2 has effects on the growth and reproduction of A. hygrophila, and the population growth rate of group-reared was faster and produced more offspring.

Short-Term Temperature Stress Modulates Fitness Traits in Bactrocera zonata, through Negative Impact on Larval Stage

The frequency and magnitude of climate extremes, especially temperature extremes (TE), are increasing, which are exposing insect populations. However, insect responses to TE are poorly understood. In this study, we investigated the impact of high-temperature (HT: 38 °C) and low-temperature (LT: 3 °C) stresses on demographic parameters and population projections of the peach fruit fly, Bactrocera zonata, a destructive pest of fruits and vegetables. Results show that the larval developmental stage was significantly increased by HT (8.30 d) and LT (8.10 d) compared with control (7.02 d). The preadult stage in the HT and LT stressed flies were 18.56 d and 18.40 d, respectively compared with control (17.37 d). Mean longevities of both males and females were also substantially prolonged in HT and LT treatments. Compared with control, the total pre-oviposition period (TPOP) and oviposition days of B. zonata were significantly increased in both stress conditions. Furthermore, female fecundity of flies significantly increased in both HT and LT (705.48 and 698.38 respectively) treatments compared with control (578.35). These findings show that temperature stresses in the larval stage delayed the larval development and increase the reproduction and life span of B. zonata. The temperature induces alteration in life-history traits that might have significant agricultural impacts on the control strategies for this key pest.

Biology of Pink Bollworm Pectinophora gossypiella (Saunders) (Gelechiidae: Lepidoptera) under Laboratory Conditions

The present study on biology of pink bollworm on two modified artificial diets separately was carried out in the Toxicology laboratory, Department of Agriculture Entomology, Post Graduate Institute, Dr PDKV, Akola during October to February 2018–19 and 2019–20 with controlled conditions such as 25±2oC temperature 65±5% RH and photoperiod of 14:10 h light: dark. Two modified artificial diets were prepared separately with some modifications in the ingredients, pink bollworm larvae are reared on two above said modified artificial diets and observations were recorded on different biological parameters like egg incubation period (days), larval period (days), pupal period (days), adult emergence (%), adult male and female longevity(days), preoviposition period (days), oviposition (days), fecundity(no of eggs per female), total life cycle(days) and on morphometry of different stages pink bollworm like egg, first, second, third and fourth instar larval stages, male and female pupa and male and female adult moth. Our results indicated that pink bollworm has four larval instars with mean larval duration of 18.60±0.54 days in modified artificial diet 1 and 17.72±0.36 days in modified artificial diet 2 population respectively. Total life cycle from egg to adult was 46.74±0.31 and 54.71±0.62 days in modified artificial diet 1 and modified artificial diet 2 population respectively. Total life cycle of pink bollworm was completed somewhat earlier in in modified artificial diet 1 in comparison to modified artificial diet 2. Our results showed that there was only a little difference in the biology of pink bollworm on both modified artificial diets, and hence both modified artificial diets can be used for laboratory rearing purposes.

Tradescantia pallida (Commelinaceae) Promotes Reductions in Plutella xylostella (Lepidoptera: Plutellidae) Populations

The feeding activity of Plutella xylostella in brassica crops can lead to large losses; thus, pesticides that prevent feeding during the larval stage or prevent the metamorphosis of this insect can be used for its control. In this study, the effects of two types of aqueous extracts of Tradescantia pallida on the different life stage of P. xylostella cycle were tested; neither of the two aqueous extracts, which were obtained by infusion and maceration, had been tested against P. xylostella. The biological variables evaluated were larval and pupal duration and viability, pupal weight, sex ratio, longevity of females, fecundity, fertility and oviposition period. There was no significant difference in the duration of the larval phase of P. xylostella between the bioassay treatments; however, larval viability was lower when the individuals were exposed to both types of T. pallida extracts. Reduced pupal viability was observed among the individuals treated with the application of the extracts. Treatment with the aqueous extract obtained by infusion caused the lowest pupal weight, fecundity, and fertility and longevity among females. The results obtained in this study allow us to propose the bioextract as an alternative for pest management, emphasizing the technique for small producers and/or organic.

Toxicological Effects of Silver and Zinc Oxide Nanoparticles on the Biological and Life Table Parameters of Helicoverpa armigera (Noctuidae: Lepidoptera)

American bollworm Helicoverpa armigera (Hubner) is a notorious pest of different agronomical and horticultural crops. Different synthetic insecticides are recommended to control H. armigera but widespread and repeated use has led to pesticide resistance in this pest. It is, therefore, necessary to develop a novel strategy to manage the population of H. armigera. Nanotechnology is the most effective and eco-friendly approach to mitigate this problem. In the present study, the bioefficacy of green synthesized nanoparticles and two different silver and zinc oxide nanoparticles with different concentrations, viz. 100, 125, 150, 175 and 200 ppm were used against the larvae. UV-vis spectrophotometer, SEM and EDX were used for nanoparticle characterization. Data were recorded daily. The result showed that in silver nanoparticles maximum larval mortality was 97%, while in zinc oxide nanoparticles, 82% was recorded against the 3rd, 4th and 5th instar of H. armigera. The effect of nanoparticles on demographic parameters was also evaluated, which increases the net reproductive rates, mean generation time and intrinsic rate in the control group compared to the treated population. After bioassay, larval and pupal duration was prolonged in the treated population compared to the control. The longevity of males, females and fecundity was also reduced. This technique will be a valuable tool in integrated pest management regimens.

The development, reproduction and P450 enzyme of the white-backed planthopper, Sogatella furcifera (Hemiptera: Delphacidae) under the sublethal concentrations of clothianidin

Clothianidin is a second-generation neonicotinoid insecticide that can effectively prevent piercing-sucking pests, such as white-backed planthopper (WBPH), Sogatella furcifera (Horváth). In this study, the sublethal effects of clothianidin on the biological traits of S. furcifera were evaluated via the age-stage, two-sex life table procedure. Our results exhibited that the female adult longevity, fecundity and hatchability of F0 generation were significantly decreased after LC10 and (or) LC30 of clothianidin exposure compared to the control. Transgenerational effects showed that the pre-adult period, female adult longevity, total longevity, oviposition days (Od), fecundity and mean generation time (T) of F1 generation were significantly decreased in the LC10 and LC30 groups compared to the control. Moreover, the development times of the third- and fifth-instar nymphs, total preoviposition period (TPOP) and doubling time (DT) were significantly shorter in the LC10 group than in the control and LC30 groups. Furthermore, the intrinsic rate of increase (ri) and finite rate of increase (λ) values of the LC10 group were significantly higher than those of the control group. However, there was no significant difference in the male adult longevity, adult preoviposition period (APOP) and net reproductive rate (R0) between the treated groups and the control. Enzyme activity and gene expression results showed that the P450 enzyme activity and mRNA levels of many P450 genes were significantly increased by clothianidin treatment. In addition, the knockdown of CYP4CE3 and CYP6FJ3, which showed the highest inducing levels, by RNA interference (RNAi) dramatically increased the toxicity of clothianidin against S. furcifera. These results indicated that sublethal concentrations of clothianidin showed a stimulatory effect on the development, but it could adversely affect the survival and reproduction of S. furcifera. Additionally, CYP4CE3 and CYP6FJ3 might play an important role in the detoxification and evolution of clothianidin resistance in S. furcifera.

Longevity and Parasitism Capacity of Psyttalia concolor (Hymenoptera: Braconidae) Fed on Sugar Solutions and Insect Honeydew

Sugars are important food sources required by adult parasitoid species to enhance their survival, fecundity and fitness. The beneficial capacity of Psyttalia concolor Szépligeti, as a biological control agent of different fruit fly pest species, is expected to increase when different sugar food sources are supplied. The objective of this study was to test the effect of seven sugars (glucose, fructose, sucrose, trehalose, melibiose, melezitose and sorbitol) on the longevity and parasitism capacity of P. concolor. Moreover, we evaluated the effect of two types of honeydew excreted by hemipteran pests present in olive trees, Saissetia oleae Olivier (Coccidae) and Euphyllura olivina (Costa) (Psyllidae) on the longevity of the parasitoid. Our results show a positive effect of carbohydrate (single sugars and honeydew) consumption on parasitoid survival. Female longevity increased when fed on sorbitol and melibiose, while males benefited from feeding on glucose and fructose, suggesting that hexose-nectars would benefit males. Sucrose increased the percentage of non-emerged hosts and parasitism rate while melezitose significantly decreased these percentages, compared to the other sugars offered. P.concolor benefited more from feeding on honeydew than on sugars, and this food item can represent an important source of energy for the parasitoid. This result indicates the importance of specific nutrients for promoting the action of P. concolor against pests.

Fecundity and Longevity of Spodoptera frugiperda (Lepidoptera: Noctuidae) at Constant Temperatures and Development of an Oviposition Model.

Fall armyworm, Spodoptera frugiperda (J.E. Smith), is a notorious invasive pest native to subtropical and tropical regions in the Western Hemisphere. It has recently invaded and established in south Asian countries and in South Korea only seasonally. Longevity, survival, and fecundity of fall armyworm were examined at different temperatures (16, 20, 24, 28, and 32°C) and an oviposition model was developed. The maximum observed fecundity was 1,485 eggs per female at 22.0°C, which decreased to ca. 815 eggs at 32.0°C. Female longevity decreased as the temperature increased up to 24°C, and then was constant around 13-14 d until temperature reached 32°C, ranging from 33.1 d at 16.0°C to 13.1 d at 32.0°C. Temperature-dependent total fecundity (TDF) was well described by the extreme value function. Age-specific cumulative oviposition rate (AOR) and age-specific survival rate (ASR) curves were fitted to logistic and sigmoid functions, respectively. The model of female adults' aging rate (1/mean longevity) as a function of temperature was used to calculate the physiological age of fall armyworm females in AOR and ASR models. Three temperature-dependent components of TDF, AOR, and ASR were incorporated to construct the oviposition model, and it was simulated to project corn damage with tentative parameters. When 10 fall armyworm females were assumed, a total of 68-74 corn ears with kernel damage were predicted. Such loss was estimated to be US$75-83 currently in the Korean market.

Callosobruchus larval competition and its consequences for male and female adults

AbstractThe struggle for life is generally the most intense among individuals of the same species because they compete to access the same food, territory, and mates. In the current study, we used Callosobruchus maculatus to investigate how males and females respond to a competitor's presence inside a bean. We monitored males' and females' from egg to adult developmental time, adult emergence, copulation success, copulatory behaviors, fecundity, egg hatching percentage, and adult longevity. Our findings revealed that a competitor's presence during immature life did not influence developmental time and adult longevity in females and males. Also, the environmental condition of living with a potential competitor in the immature stages could not significantly affect adult beetle mating behaviors compared to beetles reared alone. However, female larvae were more likely to interfere with competitors than males. Females' neighbors died sooner (mainly in the larval stage) than males (primarily as pupae). Also, when we paired males and females whose competitors died in the larval stage, female adult longevity decreased compared to without competitor control pairs. However, male adult longevity in all examined pairs was similar and was not affected by their mate's conditions. A competitor's presence during larval development decreased the insect fecundity and, at the same time, increased egg hatching percentage in all treatments regardless of the competitor's sex, or if the competitor died, compared to the control (reared alone individuals). In all, females show more interference than males toward a potential competitor.

Effects of Temperature on the Development and Survival of Cricket Species; Acheta domesticus and Gryllus bimaculatus (Orthoptera: Gryllidae)

Temperature plays an important role in the development and survival of insects. The effects of temperature on the development of two cricket species, Acheta domesticus and Gryllus bimaculatus were determined at six constant temperatures (18, 22, 26, 30, 34 and 380C). Parameters for stage-specific development such as fecundity, weight and fat content, structural body size, sex ratio, development time, and longevity were investigated. Relative humidity, light intensity, and photoperiod were set at 60-90 %, 500 ± 25 Lux, and 12:12 L:D, respectively. The results indicated that the duration of eggs and nymphal stages were significantly influenced by increased temperature. The egg-to-adult developmental period of Acheta domesticus declined from 200.5 days to 66.26 days as the temperature increased from 180C to 30 °C while that for Gryllus bimaculatus decreased from 231.82 to 62.22 days as the temperature increased from 18 to 34°C. The optimum temperature estimated for egg-to-adult ranged from 26˚C to 34˚C. Longevity of both females and males was significantly higher (female: F5, 401 = 7.5, P < 0.001; male: F5, 401 = 6.4, P < 0.001) at 18oC than at other temperatures, with the shortest recorded for Acheta domesticus (female: 20.19 days; male: 26.67 days) and Gryllus bimaculatus (Females: 25.56 days; Males: 27.49 days) at 38oC. Fecundity was highest at 26°C (1360 eggs/female/generation) and lowest at 18°C (101 eggs/female/generation) for Acheta domesticus. For Gryllus bimaculatus, the highest fecundity was recorded at 30°C (1722 eggs/female/generation) and the lowest at 18°C (123 eggs/female/generation). The optimal developmental temperature for crickets was determined to range from 26°C to 34°C. Understanding the impacts of temperature on the development of crickets would provide information on how climate change shapes insect ecologies and enable the development of forecasting models.

Toxicity and sublethal effects of diafenthiuron on life table parameters of Musca domestica L. (Diptera: Muscidae)

Housefly, Musca domestica L. (Diptera: Muscidae), is an important insect-pest owing to its disease transmitting capability in both humans and animals e.g. diarrhea, gastroenteritis diseases, lumpy skin disease, cholera. Residual insecticides are widely used to control houseflies that pose serious threat to human and animal health as well as to the environment. The population resurgence after insecticidal spray is also a common problem in many cases. Transgenerational studies can be very helpful to see the fate of insecticidal sprays. In the current study, we determined transgenerational effects of sublethal doses of diafenthiuron using Age-stage two-sex life table analysis, while focusing on potential use of diafenthiuron in baits. After treating adult flies with three different doses of diafenthiuron viz. LC10, LC20 and LC50, the progeny depicted significant changes regarding pre-adult duration (shorter in control), male and female longevity of their progeny were observed (more adult longevity in control). Additionally, population growth parameters viz. intrinsic rate of growth (r) (−0.03-0.12 per day), net reproductive rate (R0) (0.50–9.98), limiting rate of growth (λ) (0.96–1.13 per day) were also significantly reduced in the progeny of treated adults. Based on the decreased biotic potential i.e. intrinsic rate of growth and other population parameters, diafenthiuron can be recommended as an effective insecticide even at lower doses.

Resource allocation strategies for survival and reproduction by an invasive pest in response to intermittent fasting.

Intermittent fasting (IF) is a type of dietary restriction that involves fasting periods in intervals, which has been used as a strategy to improve health and extend longevity. Regular fasting is common during the process of biological invasions in nature. Yet, it is not clear how invasive animals adjust their resource allocations to survival and reproduction when periodical starvation occurs. Here, we used Tetranychus ludeni, a haplodiploid spider mite and an important invasive pest of horticultural crops around the world, to investigate the effects of IF on its life history strategies. We show that IF increased the longevity in females but not in males probably because of differences in resource storage, metabolic rate, and mating cost between sexes. In response to IF, females traded off fecundity and egg size but not the number of daughters for longevity gain, suggesting that T. ludeni females can adjust their life history strategies for population survival and growth during invasion process. Eggs produced by fasted females realized the same hatch rate and resultant young had the same survival rate as those by unfasted ones. In addition, IF had transgenerational maternal effects which prolonged offspring development period. We suggest that the longer immature developmental period can increase the body size of resulting adults, compensating egg size loss for offspring fitness. Our findings provide insight into resource allocations as responses to fasting, knowledge of which can be used for evaluation of pest invasions and for management of animal survival and reproduction by dietary regulations.

Potential of using mineral oils for the control of the mosquito bugs Helopeltis theivora (Hemiptera: Miridae) in cashew plantations

• Potentials of using an n C24 MO in controlling Helopeltis theivora were investigated. • n C24 MO application significantly reduced egg hatchability of H. theivora. • Oil extended pre-oviposition period and reduced H. theivora fecundity and longevity . • n C24 MO at 1% v/v can be used for H. theivora control in cashew plantations. This study investigated the influence of an n C24 mineral oil (MO) on some biological characteristics of a mosquito bug, Helopeltis theivora, reared on cashew under laboratory and greenhouse conditions. Aqueous emulsions of the oil were applied as sprays to eggs at four daily intervals after oviposition to assess impacts on egg hatch, and to cashew seedlings to assess adult longevity and female fecundity reared on the plants. Field applications were also carried out to assess the impacts of sprays on populations of the bug in a cashew orchard. The results of the laboratory study indicated that 1% (v/v) of the MO application reduced egg hatch when applied to eggs on cashew seedlings, in separate treatments, 1, 2, 3, and 4 days after oviposition (DAO). Egg mortality showed a negative linear correlation with egg maturity (DAO). The pre-oviposition period of adult females placed on sprayed cashew seedling, after deposits of 1% (v/v) sprays dried, was significantly prolonged. The longevity of males and females on dry oil-spray deposits was lower than on seedlings sprayed with water. The fecundity of females was also lower. Field sprays significantly reduced populations of the bug on mature cashew trees. Mixtures of MO and abamectin were more effective than oil alone. The results of the study indicate that mineral oils can be used to suppress populations of H. theivora in cashew plantations.

Lethal and trans-generational effects of Metarhizium anisopliae on red palm weevil, Rhynchophorus ferrugineus, using age-stage, two-sex life table

• The toxicity of Metarhizium anisopliae were estimated on Rhynchophorus ferrugineus . • The biological parameters of grubs were assessed by age-stage, two-sex life table. • R. ferrugineus grubs had 1.2 × 10 6 spores/mL LC 50 values of M. anisopliae. • M. anisopliae infected grubs had reduced ( R o ) , ( T ) and ( r ) values. • Adult longevity and fecundity were also reduced in infected grubs. Outbreaks of red palm weevil, Rhynchophorus ferrugineus Olivier, in Pakistan are considered a very serious threat to the date industry, owing to the sudden death of date palm trees. Current integrated management strategy largely depends on insecticides, with negative impacts on the environment. Integration of bio-control strategies incorporating entomopathogenic fungi (EPF) may provide an ecologically safe alternative. In the current study the effectiveness of Metarhizium anisopliae Sorokin against R. ferrugineus was investigated using the immersion method and the effects of this fungus on biological parameters of R. ferrugineus were estimated by age-stage, two-sex life table software. After treatment with M. anisopliae isolate (Ma-M 2 ), lethal concentration (LC 50 ) 1.2 × 10 6 spores/mL was determined against R. ferrugineus 3rd instar grubs. M. anisopliae infected grubs showed reduced net reproductive rate R o (75.55) and mean generation time T (113.886 days) and intrinsic rate of increase r (0.03797) compared to the untreated group. Also, adult longevity of males and females were significantly reduced in the M. anisopliae -infected group (F 1 ) as compared to the untreated group. Trans-generational studies revealed that grubs stage duration (69.34 days) and fecundity (181.32 eggs) of the M. anisopliae -infected group (F 1 ) were decreased compared to the untreated group. The use of lasting and adverse effects on the biological parameters of R. ferrugineus , indicate that treatment with EPF may provide an eco-friendly management strategy for this pest.

Biology of the Most Widely Distributed Sugarcane Stem Borers, Diatraea spp. (Lepidoptera: Crambidae), in Colombia.

Most studies on insect biology and ecology of sugarcane borers have focused on Diatraea saccharalis (Fabricius),the most widely distributed species in the Americas. Little information is available on the biology of other borer species present in Colombia, such as D. indigenellaDyar & Heinrich, D. busckella Dyar & heinrich,and D. tabernellaDyar, that present greater expansion and damage in sugarcane-growing regions. The biology of all four species was accordingly studied under laboratory conditions. Diatraea saccharalis presented the shortest development time (39.4days) and D. busckella the longest (58.2days). Immature survival was higher for D. saccharalis (83%) and D. tabernella (77%), with the latter also presenting the highest pupal weight (256.6mg). Observations on reproduction indicate that D. tabernella develops a larger number of egg masses per female (67.3) as compared with D. saccharalis (28.7). All three species spent more time in the pupal stage and resulted in greater pupal size than D. saccharalis; in particular, D. indigenella showed longer female longevity than D. saccharalis. High immature survival rate and greater reproductive success in D. tabernella could potentially generate a larger population in the field, whereas D. busckella takes longer to complete its development, thus increasing the chances of causing greater injury to sugarcane plants. Discussion on biology, ecology, and pest management of these little-known species is done using as model the better-known D. saccharalis.

Biology of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) on Selected Weed Species Associated with Corn in North Cotabato, Philippines

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), also known as fall armyworm (FAW), is a destructive and highly polyphagous insect pest of corn. We hypothesize that associated weed species of corn may be an alternate host of FAW. This study investigated how different weed species associated with corn – such as Rottboellia cochinchinensis (Lour.) Clayton, Ageratum conyzoides L., Amaranthus spinosus L., Celosia argentea L., Commelina benghalensis L., Corchorus olitorius L., Ipomoea triloba L., Eleusine indica (L.) Gaertn., Portulaca oleracea L., and Synedrella nodiflora (L.) Gaertn. – influenced the biology of FAW, S. frugiperda, which were collected from an infested cornfield in North Cotabato, Philippines. The life history traits of 10 weeds were compared. In R. cochinchinensis, C. benghalensis, I. triloba, P. oleracea, and E. indica, there was a high number of egg masses and the number of eggs laid by the female compared to A. conyzoides, A. spinosus, C. argentea, C. olitorius, and S. nodiflora. The duration oviposition period, as well as adult male and female longevity, yielded the same results. The percent survival was the highest (97%) for I. triloba and the lowest for A. spinosus (83.5%) and S. nodiflora (82.50%). Furthermore, no survivors were found in A. conyzoides or C. argentea. According to our findings, six weed species promoted the growth of FAW from egg to adult.

Repellence or attraction: secondary metabolites in pepper mediate attraction and defense against Spodoptera litura.

Resistance to insect pests is an important self-defense characteristic of pepper plants. However, the resistance of different pepper cultivars to Spodoptera litura larvae, one of the main insect pest species on pepper, is not well understood. Among seven pepper cultivars evaluated, cayenne pepper 'FXBX' showed the highest repellency to third instar S. litura larvae, Chao tian chili pepper 'BLTY2' showed the lowest repellency. Plant volatiles (1-hexene, hexanal, β-ionone, (E,E)-2,6-nonadienal, and methyl salicylate) affected host selection by S. litura. Among these, 1-hexene, hexanal, and β-ionone at concentrations naturally-released by pepper leaves were found to repel S. litura. Interestingly, S. litura larvae fed on the larva-attracting pepper cultivar, (BLTY2) had an extended developmental period, which was about 13 days longer than larvae fed on FXBX. Besides, the survival rate of larvae fed on BLTY2 was 22.5 ± 0.0%, indicating that the leaves of BLTY2 can kill S. litura larvae. Correlation analysis showed that larval survival rate, emergence rate, female adult longevity, and pupal weight were positively correlated with the vitamin C, amino acids, protein, cellulose, and soluble sugar contents, but were negatively correlated with wax and flavonoids contents. We identified two different modes of direct defense exhibited by pepper cultivars against S. litura. One involves the release of repellent volatiles to avoid been fed on (FXBX cultivar). The other involves the inhibition of the growth and development or the direct killing of S. litura larvae which feeds on it (BLTY2 cultivar). © 2022 Society of Chemical Industry.

Oviposition preference and life-history parameters of Callosobruchus maculatus (Coleoptera: Chrysomelidae) on different soybean (Glycine max) cultivars.

Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) is one of the most destructive pests of stored legume seeds in many regions of the world. Evaluation of varietal resistance of host seeds to C.maculatus infestation can be useful in preventing severe damage. We studied the susceptibility and resistance of eight conventional soybean cultivars (Caspian, Kosar, L17, Nekador, Sari, Tapour, Williams and Zane) based on the oviposition preference (choice and no-choice tests) and population growth parameters of the pest. Compared with other cultivars tested, oviposition preference of C.maculatus was the lowest on Nekador. The developmental time of C.maculatus differed from 40.34 days on Nekador to 48.35 days on L17, and was negatively correlated with the seed protein content. Other performance measures of C.maculatus did not match the oviposition preference. Immature survival and female longevity were highest on Caspian. The intrinsic rate of increase (rm ) was higher on Tapour, Nekador and Caspian than on Zane, Williams, and Kosar. A positive correlation was observed between the rm value of the pest and moisture content of the cultivars. Cluster analysis showed that cvs Nekador, Sari, Tapour, and Caspian were relatively susceptible, and cvs Kosar, Zane, Williams and L17 were partially resistant to this pest. Protein and moisture contents of soybean cultivars play an important role in the development and population growth of C.maculatus, and these traits could be used to develop safe and effective management strategies for this pest on stored soybean seeds. © 2022 Society of Chemical Industry.