Adult Female Longevity Research Articles

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.

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.

Pollen and nectar have different effects on the development and reproduction of noctuid moths

Although many noctuid insects are agricultural pests that threaten food production, they are also the major nocturnal pollinators of flowering plants. Larval foods of noctuid pest insects have been well studied for developing control strategies, but knowledge on host plants for the adults is rather scarce. Here, the impact of plant-derived foods on adult survival, fecundity and reproductive physiology of four global species of noctuid pests (Mythimna separata Walker, Mythimna loreyi Duponchel, Athetis lepigone Möschler, and Hadula trifolii Hufnagel) was assessed in laboratory experiments. Our results indicated that nectar slowed testis decay and prolonged the oviposition period and lifespan, increasing fecundity. Acacia nectar increased the longevity of male and female adults by 3.2∼10.9 and 2.4∼5.0 days, respectively, and fecundity of females by 1.22∼3.34 times compared to water-fed individuals. The fitness among the different species of noctuid moths differed on specific pollen diets. On pine pollen, the fecundity of female moths of M. separata, A. lepigone and H. trifolii was 10.06, 33.52, and 28.61%, respectively, lower than those of the water-fed females, but the fecundity of female moths of M. loreyi on pine pollen was 2.11 times greater than for the water-fed individuals. This work provides valuable information on the nutritional ecology for noctuid moths, which can aid the development and design of nutritional attractants within noctuid pests-infected cropping systems and provide a basis for effective and targeted management of global noctuid pests.

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.

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 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.

A sublethal concentration of afidopyropen suppresses the population growth of the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae)

The cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is an important insect pest of cotton crops worldwide. The objectives of this study were to determine the acute toxicity of afidopyropen and whether there are any effects of sublethal concentrations of afidopyropen on the biological characteristics of A. gossypii. The results showed that afidopyropen possesses high acute toxicity to adult A. gossypii with a 72 h LC50 value of 1.062 mg L–1. A sublethal concentration (LC10) of afidopyropen significantly decreased adult longevity, fecundity and oviposition days of female adults in both F0 and F1 generations. The total pre-adult survival of F1 progeny was also significantly reduced by 30% at the LC10 of afidopyropen. In addition, the nymph developmental time, pre-adult period, adult pre-reproductive period (APRP), and total pre-reproductive period (TPRP) of the F1 progeny were significantly prolonged compared with the control. Several population parameters, including the net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (λ) of F1 progeny were significantly decreased by a sublethal afidopyropen concentration exposure. These results indicated that sublethal concentration of afidopyropen can significantly suppress A. gossypii population growth. It would be useful for assessing the overall effects of afidopyropen on A. gossypii.

Global water quality changes posing threat of increasing infectious diseases, a case study on malaria vector Anopheles stephensi coping with the water pollutants using age-stage, two-sex life table method.

BackgroundWater pollution due to uncontrolled release of chemical pollutants is an important global problem. Its effect on medically important insects, especially mosquitoes, is a critical issue in the epidemiology of mosquito-borne diseases.MethodsIn order to understand the effect of water pollutants on the demography of Anopheles stephensi, colonies were reared in clean, moderately and highly polluted water for three consecutive generations at 27 °C, 75% RH, and a photoperiod of 12:12 h (L:D). The demographic data of the 4th generation of An. stephensi were collected and analysed using the age-stage, two-sex life table.ResultsThe intrinsic rate of increase (r), finite rate of increase (λ), mean fecundity (F) and net reproductive rate (R0) of An. stephensi in clean water were 0.2568 d−1, 1.2927 d−1, 251.72 eggs, and 109.08 offspring, respectively. These values were significantly higher than those obtained in moderately polluted water (r = 0.2302 d−1, λ = 1.2589 d−1, 196.04 eggs, and R0 = 65.35 offspring) and highly polluted water (r = 0.2282 d−1, λ = 1.2564 d−1, 182.45 eggs, and R0 = 62.03 offspring). Female adult longevity in moderately polluted (9.38 days) and highly polluted water (9.88 days) were significantly shorter than those reared in clean water (12.43 days), while no significant difference in the male adult longevity was observed among treatments.ConclusionsThe results of this study showed that An. stephensi can partially adapt to water pollution and this may be sufficient to extend the range of mosquito-borne diseases.

Effect of cold storage on development and demographic parameters of Scolothrips longicornis fed on two-spotted spider mite.

Cold storage effects on the female predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch eggs for different time periods (5, 10, 20 and, 30 days) at 5 or 25 °C (control) on development and life table parameters were examined. Female adult duration and female total longevity were not influenced by the period of cold storage. The minimum mean female total longevity (28.1 ± 0.32 day) was observed in the 30-day treatment. The oviposition period decreased with increasing cold storage duration. All life table parameters of S. longicornis demonstrated a significant difference across treatments. Our results demonstrated that the female adult of S. longicornis could be maintained at 5 °C for 5-days with minimal reduction in the life-history process. This would be beneficial in the storage and mass production of S. longicornis in biocontrol programs involving T. urticae.

Life history traits of the parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae) on three beetle hosts

Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) is a wasp biocontrol agent used against larvae and pupae of coleopteran pests in warehouse settings. The objectives of this study were to assess the life history and life table parameters of A. calandrae reared on three coleopteran pests: Acanthoscelides obtectus (Say), Callosobruchus chinensis (L.), and Lasioderma serricorne (F.). The results suggest that host species identity influenced the developmental duration, fecundity, and body size of A. calandrae. When reared on L. serricorne, the parasitoid's pre-adult period was the shortest (15.68 d), but it had the highest female adult longevity (31.79 d) and fecundity (162.04 progeny per female). Higher values of net reproductive rate (R0), intrinsic rate (r), and finite rate (λ) of A. calandrae were also recorded for its population reared on L. serricorne. Further, the L. serricorne host enabled A. calandrae females to attain a larger body size (2.59 mm) than those reared on A. obtectus (2.44 mm) or C. chinensis (2.48 mm). Our results demonstrated that, in comparison with A. obtectus and C. chinensis, the most suitable host for A. calandrae is L. serricorne. The implications of our results for biological control of these three host pests are discussed.

Biology of Leaf Eating Caterpillar Trilocha varians (Walker) on Ficus microcarpa

The biology of Trilocha varians (Walker) was studied on Ficus microcarpa L.f. under laboratory conditions in Jodhpur, Rajasthan. The fecundity ranged from 140-200 and incubation period was 3-5 days. It has five larval instars, with total larval and pupal period being 16-22 and 10-15 days, respectively. The adult male and female longevity were 4-7 and 6-12 days, respectively.

Sublethal effects of nitenpyram on the biological traits and metabolic enzymes of the white-backed planthopper, Sogatella furcifera (Hemiptera: Delphacidae)

Neonicotinoid insecticide nitenpyram is widely used in controlling rice hoppers including Sogatella furcifera (Horváth). At present, the effects of nitenpyram on the biological traits and metabolic enzymes of S. furcifera remain unclear. In this study, we applied an age-stage, two-sex life table to evaluate the sublethal effects of nitenpyram on S. furcifera under one- or multi-generation exposure. Fecundity of F0 individuals was significantly decreased in the LC25 treatment group compared to the control. Additionally, in contrast to control, the preadult period, male adult longevity, female adult longevity, longevity, total preoviposition period (TPOP), oviposition days and fecundity were significantly decreased in the F1 and F6 generations, while the development time of the 1st, 3rd and 5th -instar in the F6 generation were significantly shorter than the control and (or) the F1 generation. Moreover, except for the mean generation time (T) that was significantly decreased in the F1 and F6 generations, other population parameters such as the intrinsic rate of increase (ri), finite rate of increase (λ) and net reproductive rate (R0) were not influenced by nitenpyram exposure. The P450 and EST were both significantly increased in the F0 and F6 individuals after nitenpyram (LC25) treatment, and the P450 showed a higher activity in the F6 generation than F0. The mRNA levels of four P450 genes (CYP4CE3, CYP417A4, CYP439A3 and CYP6FJ3) were induced by nitenpyram (LC25) treatment in both the F0 and F6 generation, and these four P450 genes were also significantly upregulated in the F6 generation compared with F0. Our findings are useful for developing rational application strategies for using pesticides and understanding the metabolic resistance of nitenpyram in S. furcifera.

Cold storage of Spodoptera litura eggs and Telenomus remus adults for improving mass‐rearing efficiency

AbstractTelenomus remus (Nixon) has shown promising potential as a biological control agent for the major invasive agricultural pest, Spodoptera frugiperda (J. E. Smith). Application of biological control programmes in the field requires an efficient mass‐rearing system to provide sufficient numbers of beneficial insects. The short longevity of parasitoid adults and limited period of availability of host eggs are two factors affecting the mass‐rearing efficiency of T. remus. Using Spodoptera litura (Fabricius) eggs as an alternative host, the effects of cold storage of S. litura eggs and T. remus adults at 5°C, 8°C and 11°C for different time durations on the fitness of the parasitoid were investigated to identify the most suitable storage conditions. Results showed that T. remus can successfully exploit stored S. litura eggs, but the number of parasitized eggs decreased with increased egg storage duration and/or reduced storage temperature. For refrigerated adults, the survival rate declined gradually with longer storage duration, and the females' survival rate was higher than the males' at any treatment. Similarly, parasitism capacity of stored adults declined significantly with prolonged storage. Female adult longevity was significantly shorter than the control for all treatments. However, the offspring emergence rate and percentage of females were barely affected by cold storage. In conclusion, S. litura eggs can be stored at 11°C for up to 9 days and adult T. remus can be stored at 8°C or 11°C for up to 7 days without significant losses. Data obtained from this study will help coordinate different aspects of T. remus production, decreasing costs and improving the biocontrol materials' availability.

Evaluation of the Toxic Effects of Novaluron on Muscina stabulans (Fallen) (Diptera: Muscidae).

The worldwide fly species, Muscina stabulans (Diptera: Muscidae) is known as 'false stable fly'. It has veterinary, forensic and medical importance. The present study aimed to examine the toxicity of novaluron (chitin synthesis inhibitor) via its effect on the growth and reproductive potential of M. stabulans. The early last (3rd) instar larvae and prepupae have been treated with novaluron using five doses: 5.0, 1.0, 0.5, 0.1 and 0.01 μg/larva. Student's t-test analysis has been used for data processing as well as refined by Bessel correction for significant differences among means. Current study revealed that, after the treatment different mortalities of larva, pupa and adult have been estimated. LD50 values of novaluron were 0.018 and 0.057 μg/insect, respectively. Furthermore, the larval period was insignificantly shortened while the pupal duration has been significantly extended and the developmental rate has been slightly enhanced. On the other hand, the adult longevity of females was considerably reduced and the adult emergence was considerably blocked, regardless the dose. However, only after the treatment, some deformed pupae were observed and some adult deformities were observed. Both fecundity and fertility were drastically reduced and sterilizing activity on novaluron increased in a dose-dependent course, regardless the time of treatment. Novaluron can be used as an effective IGR in the integrated control program for this medically and veterinary serious fly.

Influence of an elevated CO2level on life history parameters and hormone pathway or vitellogenin metabolism of the brown planthopper

AbstractThe growth, development and reproduction of herbivorous insects could be altered due to changes in quality and quantity of their host plants under elevated CO2. The brown planthopper,Nilaparvata lugens, is one of the most serious and destructive economic pests in rice growing areas in Asia. In this study, we investigated the effect of elevated CO2on the growth, development and reproduction ofN. lugensand, in particular, on the hormonal regulation of the transcription factors inN. lugens. The results indicated that compared with ambient CO2, elevated CO2significantly shortened the duration of egg and nymph, longevity of female adults and total adults, and significantly decreased the weight of adults; besides, elevated CO2significantly improved the fecundity of female adults, egg hatching rata and the transcription levels ofVg. The relative expression levels ofJHMAT‐andFAMeT‐regulated synthesis of JH were first down‐regulated and then up‐regulated with the development of the 5th instar nymph ofN. lugensunder elevated CO2. In addition, the relative expression level ofcyp314a1played an important role in synthesis of ecdysone was up‐regulated in the 5th instar nymph ofN. lugensunder elevated CO2. We have demonstrated that elevated CO2could accelerate the development and improve the reproduction ofN. lugens, which is related to the transcription levels of JH, MH and Vg.

Sex-specific developmental trajectories in an extremely sexually size dimorphic spider.

Adult body size, development time, and growth rates are components of organismal life histories, which crucially influence fitness and are subject to trade-offs. If selection is sex-specific, male and female developments can eventually lead to different optimal sizes. This can be achieved through developmental plasticity and sex-specific developmental trajectories. Spiders present suitable animals to study differences in developmental plasticity and life history trade-offs between the sexes, because of their pronounced sexual dimorphism. Here, we examine variation in life histories in the extremely sexually size dimorphic African hermit spider (Nephilingis cruentata) reared under standardized laboratory conditions. Females average 70 times greater body mass (and greater body size) at maturity than males, which they achieve by developing longer and growing faster. We find a small to moderate amount of variability in life history traits to be caused by family effects, comprising genetic, maternal, and early common environmental effects, suggesting considerable plasticity in life histories. Remarkably, family effects explain a higher variance in male compared to female life histories, implying that female developmental trajectories may be more responsive to environment. We also find sex differences in life history trade-offs and show that males with longer development times grow larger but exhibit shorter adult longevity. Female developmental time also correlates positively with adult body mass, but the trade-offs between female adult mass, reproduction, and longevity are less clear. We discuss the implications of these findings in the light of evolutionary trade-offs between life history traits.

Multiple Mating of Aphelinus asychis Enhance the Number of Female Progeny but Shorten the Longevity.

Simple SummaryAphelinus asychis Walker is an arrhenotocia endoparasitoid against the devastating vegetable pest Myzus persicae. Unmated Aphelinus asychis females only produce male progeny, and mated female adults produce male and female progeny. Because only female adults can kill the target pest by parasitism and feeding, the control efficiency of Aphelinus asychis was mainly affected by the percentage of female adults. We found that Aphelinus asychis females could mate multiple times to receive more sperm in their life span, which was beneficial for enhancing the number and percentage of female progeny. In addition, backcrossing is critical for population increase when the proportion of males is low. We also found that there was no significant difference in the population fitness of Aphelinus asychis between backcross and control treatments.The Aphelinus asychis female adult is an important arrhenotocous parthenogenesis parasitoid of Myzus persicae, and its reproductive mode is beneficial for the population continuation of A. asychis by way of multiple mating and backcross. To explore the effect of mating on the population fitness and control efficiency of A. asychis, its mating frequency and backcross were observed under laboratory conditions. The results showed that most matings in A. asychis involved four distinct stages: courtship, pre-copulatory, copulation, and post-copulatory behaviours. Only the duration of courtship increased significantly with an increase in copulation frequency for females, and the courtship duration of A. asychis females mated with different males were significantly shorter than those mated with the same male at the same mating times, which suggested that A. asychis females might prefer to mate with different males to enrich the genotype of their offspring. The total number of mummified aphids and the female and male longevity decreased significantly with an increase in mating frequency. On the contrary, female progenies increased significantly with an increase of mating frequency, suggesting that sperm limitation might occur in females when they only mated once. These results imply that females might prefer to receive more sperm by mating multiple times in their life span. In addition, we found that the intrinsic rate of increase (r) of A. asychis of the control group (0.2858 d−1) was significantly greater than that in the backcross treatment (0.2687 d−1). The finite killing rate (θ) of A. asychis of the control group was similar to that in the backcross treatment, which showed that this treatment had a negligible negative effect on the control efficiency of A. asychis. In conclusion, the results showed that multiple mating increased the number and proportion of A. asychis female progenies but shortened the longevity of female and male adults, while the negative effect of backcross on the control efficiency of A. asychis was negligible.

Biology of Tortoiseshell Beetle (Aspidomorpha miliaris Fabr.) on Sweetpotato (Ipomoea batatas Lam) and Its Relatives as Affected by Hosts’ Nutritional Profile

Several insect pests attack the foliage of sweetpotato at different stages of crop growth which contribute to yield reduction. Weeds belonging to the same genera as the main host can act as alternate hosts of insect pests. The study evaluated the biology of tortoiseshell beetle in the laboratory at an ambient temperature of 27-30oC and 85-90% RH on sweetpotato (Ipomoea batatas) as main host and four other Ipomoea species: three-lobe morning glory (I. triloba), beach morning glory (Ipes-caprae), swamp morning glory (I. aquatica), and five-finger morning glory (I. pentaphylla Syn. I. cairica) as alternate hosts. The beetle underwent four developmental stages – egg, larva, pupa, and adult. It completed its development within 4-6 weeks from egg-laying to adult emergence of 26-40 days, an average of 27.55 to 39.01 days. The total development period of male and female A. miliaris on I. batatas, I. triloba, I. pes-caprae, I. aquatica, and I. pentaphylla were 27.55 and 30.72, 27.52 and 30.49, 29.94 and 35.06, 33.25 and 38.11, and 33.70 and 39.01 days, respectively. Adult longevity of males and females was longer on I. batatas and I. triloba, followed by I. aquatica), I. pentaphylla, and lastly, I. pes-caprae. The highest number of eggs laid was recorded in I. batatas (202.7), followed by I. triloba (173.2), I. pes-caprae (76.0), I. aquatica (71.7), and I. pentaphylla (59.7). The highest egg viability of more than 90% was recorded in I. batatas and I. triloba. Mortality occurred towards the later part of larval development, with the lowest mortality of 8.33% in I. batatas. The host plants ‘ high protein, N, P, and K contents influenced the shorter life cycle, higher reproductive rate, high percentage egg hatchability, lower mortality, and longer life span. Increased mortality and abnormal wet frass in I. pes-caprae could be accounted for by exceptionally high sugar content in the leaves and secondary metabolites present, especially in other host plants that may have insecticidal activity. Since A. miliaris was also able to complete its life cycle and reproduce on the four weed species, the insect continues to survive without sweetpotato. Any management strategy for this insect by destroying the Ipomoea weed hosts eliminates other sources of infestation in the field.

Development and population growth of the two-spotted spider mite (Tetranychus urticae Koch) on strawberry fertilized with different doses and sources of organic fertilizers

ABSTRACT This study deals with the evaluation of the biological parameters and population growth of TSSM in strawberry fertilized with different doses and sources of organic fertilizers. Plants were grown in a greenhouse where the treaments were: Bokashi compost, Penergetic®, boiled chicken manure solution at 2.5%, 5%, 7.5%, and 10% concentrations; and control (unfertilized plants). The immature duration, adult females longevity, number and viability of eggs were determined through mite rearing on leaf disks taken from the treated plants. Populations of TSSM adult females on strawberry leaves were also recorded in greenhouse. In addition, the levels of nitrogen, potassium and phenolic compounds were determined in leaves. Shorter immature period, higher female longevity, higher number and viability of eggs were obtained for TSSM reared on Bokashi fertilized plants. Denser adult TSSM population was also found on Bokashi fertilized plants in greenhouse. A moderate and positive correlation was observed between nitrogen foliar levels and egg numbers, adult female longevity, as well as between potassium foliar amount and mites density. The leaf content in phenolic compounds was correlated positively with the deutonymph duration and negatively with population density recorded in greenhouse.