Gross Reproductive Rate Research Articles

Multigenerational hormetic effects of different insecticides on Spodoptera frugiperda (J.E. smith) (Lepidoptera: Noctuidae)

To protect crops from pest insects, farmers continuously use insecticides, which eventually degrade into residue due to abiotic or biotic factors. These residual effects of pesticides may cause low lethal and/or sublethal impacts on the exposed pest insect populations, leading to the induction of pest resurgence through hormesis and ultimately the development of resistance. Hormesis is a beneficial bi-phasic effect generally characterized by low-dose reproductive stimulation and high-dose inhibition. In the present study, we investigated the impact of low lethal and sublethal concentrations (LC10, LC20, and LC30) of spinetoram, chlorantraniliprole, and thiodicarb on the F0 generation as well as their multigenerational hormesis effects on the F1 and F2 generations of Fall Armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). The study focused on reproductive parameters, fecundity, fertility, and life index parameters such as net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), mean length of generation (Tc), and gross reproductive rate (GRR). Fecundity of S. frugiperda increased by 4.82%, 4.63% and 4.58%, while eggs fertility improved by 7.77%, 6.78% and 6.52% at LC10 of thiodicarb, chlorantraniliprole and spinetoram, respectively, from the F1 to F2 generation. Further, interaction analysis (Concentration × Insecticidal treatments) revealed that important vital parameters like pre-oviposition period (POP), oviposition period (OP), post-oviposition period (PtOP), R0,rm,λ, Tc and GRR of F0 were negatively impacted by LC30 of all the tested insecticides and LC20 of only spinetoram. However, LC10 of any of the tested insecticides did not affect these parameters when compared with control. Furthermore, interactive analysis in multigenerational exposure experiments (Concentration × Insecticidal treatments × Generation(s)) showed hermetic effects of LC10 of all tested insecticides which is more positive in F2 as compared to F1 generation. These unwanted positive hermetic effects of low lethal concentrations (LC10) of tested insecticides in offspring of exposed parental population of S. frugiperda indicated its resistance and/or resurgence. Furthernore, present study emphasizes the necessity for additional research to elucidate the underlying mechanisms responsible for these effects.

Toxicity and fitness evaluation of Chrysoperla carnea resistant strains on cotton mealy bug Phenacoccus solenopsis Tinsely

Research was conducted to select chlorantraniliprole and bifenthrin resistant strains of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) at Bahauddin Zakariya University, Multan, Pakistan. Moreover, fitness parameters of resistant C. carnea were evaluated after feeding on 2nd instars nymph of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). Two to three day old C. carnea larvae were used in each topical bioassay. The raw data of biological parameters were analysed using an age stage, two sex life table. After 16 and 13 rounds of selection, the Chlo-Sel and Bife-Sel strains of C. carnea developed 91- and 2.19-fold resistance level, respectively compared with the UN-Sel strain. Biological parameters such as larval duration (days), pupal duration (days), female longevity (days), male longevity (days), adult pre-oviposition period (APOP) (days), total pre-oviposition period (TPOP) (days), oviposition (days), reproductive female ratio (RepF/Fn), and fecundity/female (F) were significantly different while pre-adult female (days), pre-adult male (days), and female ratio (Nf/N) was not significantly different among all strains. Demographic parameters such as finite rate of increase (λ), mean generation time (T), intrinsic rate of increase (r), net reproductive rate (Ro), and gross reproductive rate (GRR) were significantly different while doubling time (DT) was significantly similar among all strains of C. carnea. This information could be helpful in developing and promoting the use of insecticide resistant strains of C. carnea for the management of P. solenopsis under field conditions. Moreover, knowledge of fitness advantages will be helpful in IPM for the development of control strategies against P. solenopsis. In order to explore the practical relevance of our findings, more research ought to be conducted.

Unraveling the impact of greenhouse pepper resistance on biological performance of the broad mite Polyphagotarsonemus latus (Acari: Tarsonemidae)

The broad mite, Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) is a highly significant pest in tropical and subtropical regions, with a wide host range that encompasses over 60 plant families. In particular, it can be a major and economically damaging pest on pepper plants, causing significant losses to the crop. The life table parameters of P. latus were determined under laboratory conditions to evaluate the susceptible and resistant cultivars of greenhouse pepper among 14 pepper cultivars, including Selva, Clavesol, Kamus, Chidem, Sympathy, Sven, Kamro, Lumos, Caoba, Bellisa, Sunset, Atlantic D90, Atlantic G50, and Atlantic P5001. The total pre-adult period was significantly different on the pepper cultivars tested, in which the shortest and longest duration was recorded on Atlantic P5001 (5.02 days) and Atlantic G50 (5.94 days), respectively. Adult longevity and total life span had significant differences among pepper cultivars, in which the longest durations were observed on Kamus (21.02 and 26.36 days, respectively). The population growth parameters, including the gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and mean generation time (T), as well as the fecundity of the broad mite exhibited significant differences among the cultivars tested. Specifically, the maximum and minimum values of the intrinsic rate of increase (r) were observed in Lomus (0.319 day−1) and Sunset (0.242 day−1), respectively. The gross reproductive rate (28.33 eggs/individual) and net reproductive rate (27.18 eggs/individual) in the Kamus cultivar were significantly higher than those in the other cultivars. Our results indicated that among the pepper cultivars, Sunset, Sympathy, Chidem, and Clavesol were more resistant to P. latus compared with the others.

An evaluation of the growth, development, reproductive characteristics and pest control potential of three Trichogramma species on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

Tuta absoluta is an invasive alien species that has caused major losses in the Chinese tomato industry. Investigating the growth, development, reproduction and pest control effects of three native species of Trichogramma species on the eggs of T. absoluta could provide an ecological tool for preventing and controlling T. absoluta in China. In this study, we constructed age-stage two-sex life tables for three common species of Trichogramma and determined their relative abilities to control T. absoluta in greenhouse insect cages, thus allowing us to identify the species with the most effective ability to prey on T. absoluta eggs. Analysis showed that the net reproductive rate (R0), gross reproduction rate (GRR) and intrinsic rate of increase (r) of Trichogramma ostriniae were the highest of the three species at 22.85, 32.58 and 1.31, respectively. In the presence of 10 eggs and under ideal conditions, T. ostriniae, Trichogramma chilonis, and Trichogramma dendrolimi produced 9451.04, 5199.56, and 1902.95 offspring, respectively. Following the release of T. ostriniae, tomato leaves incurred a damage index of 1 after the first week, while the number of T. absoluta reduced to 24.60 individuals by week 10 (8.75% of the control treatment). Of the three species of Trichogramma tested in this study, T. ostriniae exhibited the best growth, development, reproductive capacity and predatory ability against T. absoluta, and has broad application prospects. © 2024 Society of Chemical Industry.

The impact of different photoperiod regimes on vital life traits of Amblyseius swirskii and Neoseiulus cucumeris (Acari: Phytoseiidae).

Environmental factors, such as photoperiod can play an important role in the development and performance of predatory mites. The influence of five photoperiod regimes (0: 24, 8: 16, 12: 12, 16: 8, and 24: 0h; Light: Dark) on the population parameters of the predatory mites, Amblyseius swirskii Athias-Henriot and Neoseiulus cucumeris (Oudemans) was studied under the laboratory conditions at 25°C and 25 ± 1°C, 65 ± 5% RH. Regarding A. swirskii, the longest and shortest total pre-adult and total preoviposition periods (TPOP) were in the photoperiod of 12L:12D and 16L:8D, respectively. The oviposition days, adult longevity, total life span, fecundity, gross reproductive rate (GRR), and net reproductive rate (R0) of the predator had no significant difference in all photoperiods tested. The intrinsic rate of increase (r) and the finite rate of increase (λ) in 16L:8D photoperiod had no significant difference with the other photoperiods tested except 12L:12D. Regarding N. cucumeris, the shortest total pre-adult and TPOP were in full darkness. The oviposition days and fecundity were significantly higher in 16L:8D than the others. The value of R0 in 16L:8D was significantly higher than 8L:16D. The highest values of the parameters r and λ were observed in full darkness, which had no significant difference with 16L:8D and 24L:0D. According to the results, the photoperiod regime had a more significant influence in terms of development and reproduction on N. cucumeris than A. swirskii, and 16:8 (L: D) h photoperiod was recognized as the proper regime for their rearing.

Effects of Melia azedarach extract on demographic and biochemical characteristics of the cabbage aphid, Brevicoryne brassicae

The cabbage aphid, Brevicoryne brassicae L. (Aphididae: Hemiptera) a destructive aphid, is native to Europe and is now found in many other parts of the world. Currently, one of the main problems of Iranian cabbage growers is the significant damage caused by this pest. Also, due to the fresh eating of cabbage, it is necessary to use non-chemical methods to control the pests. Our bioassay tests showed that Melia azedarach L. (Meliaceae) fruit extract showed high toxicity to cabbage aphid. In this study, sublethal effects of M. azedarach extract was investigated on some demographic and biochemical properties of B. brassicae. The results showed that the sublethal concentrations (LC10 and LC20) and LC50 values were 0.68, 1.16, and 3.42 μg/ml, respectively. Compared to the control, sublethal concentrations of insecticide significantly decreased the gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), intrinsic rate of birth (b), intrinsic rate of death (d), weekly growth rate (rw), reproductive rate and adult longevity of the pest. Meanwhile, the mean generation time (T) and population doubling time (DT) of this aphid increased significantly. Additionally, sublethal doses of insecticide reduced the energy reserves of the pest such as carbohydrate, protein and lipid content compared to the controls. In addition to modify the pH, this extract also changed the distribution and concentration of sodium and potassium ions in haemolymph. Therefore, sublethal concentrations of M. Azedarach fruit extract can be used in the management program of B. brassicae.

A comparative approach for life history and functional response demonstrates similar survival strategies for Trichogramma evanescens and T. pintoi.

Egg parasitoids are important biological control agents of lepidopteran pests of agricultural crops. Trichogramma evanescens Westwood and T. pintoi Voegele (Hymenoptera: Trichogrammatidae) are egg parasitoids with worldwide importance. The parasitoid selection necessitates comparative assessment of the life table traits and functional response analysis to provide insights into their effectiveness in pest control. In this study, we examined theirlife table traits including survivorship and reproductivity, and functional response and associated parameters i.e., attack coefficient and handling time. Life table parameters, using age-stage, two-sex theory, revealed similar survival and reproductive strategies for both species. For example, the female longevity, oviposition days and fecundity did not differ between both species. Exceptionally, the male longevity of T. evanescens was shorter than that of T. pintoi. The population growth parameters such as gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ), and mean generation time (T) did not differ between species. The polynomial logistic regression yielded a type III functional response and a non-linear least square analysis revealed different attack coefficient and similar handling time. However, their parasitism rate differed between the lowest (five eggs) and highest (80 eggs) initial host egg densities such that T. evanescens had a lower parasitism rate at the lowest density and higher parasitism rate at the highest density. The similarity in survival strategies and minor differences in host handling of both parasitoids are discussed in terms of relevance to applied biological control applications and evolutionary traits. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Combining temperature-dependent life table data into Insect Life Cycle Model to forecast fall armyworm Spodoptera frugiperda (JE Smith) distribution in maize agro-ecological zones in Africa.

The fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), an invasive agricultural pest, has significantly impacted crop yields across Africa. This study investigated the relationship between temperature and FAW life history traits, employing life cycle modeling at temperatures of 20, 25, 28, 30, and 32°C. The development time for eggs, larvae, and pupae varied from 0-3 days, 10-18 days, and 7-16 days, respectively. The optimal temperature range for immature stage survival and female fecundity was identified as 21-25°C, with the intrinsic rate of increase (rm) and gross reproductive rate (GRR) peaking at 25-28°C. Model validation confirmed the accuracy of these findings. The research further projected the Establishment Risk Index (ERI), Activity Index (AI), and Generation Index (GI) for FAW under current and future climates (2050 and 2070) using RCP 2.6 and RCP 8.5 scenarios. Results indicate that RCP 2.6 leads to a reduction in high-risk FAW areas, particularly in central Africa. Conversely, RCP 8.5 suggests an increase in areas conducive to FAW activity. These findings highlight the impact of climate policy on pest dynamics and the importance of incorporating climatic factors into pest management strategies. The study predicts a potential decrease in FAW prevalence in West Africa by 2070 under aggressive climate mitigation, providing a basis for future FAW management approaches.

Examining Innovative Technologies: Nano-Chelated Fertilizers for Management of Wheat Aphid (Schizaphis graminum Rondani).

The use of nanofertilizers has both advantages and concerns. One benefit is that nano-fertilizers can enhance plant resistance against insect pests, making them a valuable strategy in integrated pest management (IPM). This study focused on the effect of wheat leaves treated with nano-chelated fertilizers and nitrogen (N) fertilizer on the wheat aphid (Schizaphis graminum Rondani), a harmful pest of wheat plants that transmits dangerous viruses. The nano-Cu treatment showed the longest pre-adult longevity. Additionally, the nano-Cu treatment resulted in the lowest adult longevity, fecundity, nymphoposition day number, intrinsic rate of population growth (r), finite rate of population increase (λ), and net reproductive rate (R0) and gross reproductive rate (GRR). Also, nano-Cu treatment led to the highest amount of (T). The N treatment led to the highest levels of fecundity, nymphoposition days, r, λ, and R0. Nano-Fe and nano-Zn demonstrated fewer negative effects on S. graminum life table parameters than nano-Cu. Our results indicate that N treatment yielded numerous advantageous effects on the wheat aphid while simultaneously impeding the efficacy of the aphid control program. Conversely, nano-Cu treatment exhibited a detrimental influence on various parameters of the aphid's life table, resulting in a reduction in the pest's fitness. Consequently, the integration of nano-Cu should be seriously considered as a viable option in the IPM of the wheat aphid.

Aphid‐induced phytochemicals in Brassica juncea (L.) Czern & Coss. afflicting host preference and bionomics of Lipaphis erysimi (Kaltenbach)

AbstractBionomics of an insect and metabolic flux of the host plant are important tools to decipher the status of plant resistance against insect species. This study illuminates vital information on aphid‐induced levels of phytochemicals in the siliquae of Brassica juncea cultivars and their effect on host selection and population growth parameters of Lipaphis erysimi. The current study unveiled that the siliquae preference, intrinsic rate of increase (r), finite rate of increase (λ), gross reproductive rate (GRR) and net reproductive rate (R0) were significantly lower on Pusa Mustard 27, DRMR 150‐35, RLC 3, NRCHB 101, Pusa Mustard 26 and Pusa Mustard 25. However, the mean generation time (T) and doubling time (DT) of L. erysimi were significantly longer (p < 0.001) in these genotypes. These cultivars were also found with elevated levels of aphid‐induced phytochemicals and their associated enzymes, except in a few cases. Total antioxidants, ferric ion reducing antioxidant power, chlorophyll A, total chlorophyll, ascorbate oxidase (AO), catalase, phenylalanine ammonia lyase (PAL) and myrosinase were found to contribute 49.18–85.30% variation for siliquae preference and bionomics of L. erysimi on the test B. juncea cultivars. The study revealed that phenols, antioxidants, chlorophyll A, chlorophyll B, total carotenoids, AO, ascorbate peroxidase, PAL, tyrosine ammonia lyase and myrosinase had significant and negative direct consequences on the siliquae preference and bionomics, thus can be exploited as biochemical markers to identify sources of resistance against L. erysimi. Furthermore, DRMR 150‐35, NRCHB 101, RLC 3, Pusa mustard 26, RH 749 and Pusa Mustard 27 were found with greater aphid‐induced defence phytochemicals and detrimental effects on the host selection and bionomics of L. erysimi, thus can be deployed in Brassica improvement program.

Biology of Spodoptera frugiperda (Lepidoptera: Noctuidae) on different types of plants feeds: Potency as a pest on various agricultural plants

Abstract Spodoptera frugiperda is a new invasive and highly polyphagous pest that attacks corn in Indonesia. The availability of abundant plant species allows pests to switch to other host plants to maintain their population. The aim of this research is to examine the development, reproduction, nutritional indices, and life table of S. frugiperda in several plant species. The plants tested were corn, rice, broccoli, oil palm, and baby corn as controls. Ten individual insects were used and the experiments were repeated five times for each plant species. The test results show that different types of plant feed affect the development time, imago life span, fecundity, and fertility of S. frugiperda. Baby corn fruit and broccoli had higher net reproduction value (R 0), intrinsic growth rate (r), gross reproduction rate (GRR), shorter mean generation period (T), and population doubling time (DT) than corn and rice leaves. On oil palm leaf feed, no population parameters could be determined because no larvae developed into adults and had the lowest nutritional indices parameters, so that, oil palm could not be exploited as a host plant. Also, the nutritional indices of several feed plant species tested provided information that broccoli could be the most suitable host compared to other plants tested when there was no corn in the field.

Chemotaxis response and age-stage, two-sex life table of the Cheilomenes sexmaculata (Fabricius) (Coccinellidae: Coleoptera) against different aphid species.

The Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae), is one of the most beneficial and identifiable predators of numerous soft-bodied and sucking insect pests of several crops. Biological parameters and olfactory response of C. sexmaculata were investigated under laboratory conditions by providing three different aphid species i.e., mustard aphid (Lipaphis erysimi Kaltenbach), citrus black aphid (Toxoptera citricida Kirkaldy), and peach aphid (Diuraphis noxia Kurdjumov) as a food source. The developmental period of immature stages of C. sexmaculata was shorter on D. noxia as compared to other aphid species. The adult longevities were longer on D. noxia and T. citricida while shorter on L. erysimi. Female fecundity was highest on D. noxia while lowest on L. erysimi. Life table parameters i.e., intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (Ro), and gross reproductive rate (GRR) were maximum on D. noxia while minimum on L. erysimi. The mean generation time C. sexmaculata was 20.90, 23.69, and 26.2 days on D. noxia, L. erysimi, T. and citricida, respectively. These findings were further confirmed from the olfactory experiment where D. noxia proved to be the most preferred prey. This study provides necessary information for mass-rearing of C. sexmaculata.

Biology and Demographic Statistic Myzus persicae on Chili Plant

This research aimed to observe the biological aspects and demographic data of Myzus persicae on chili plants. The research was conducted at the Laboratory of Pests and Wire House, Department of Plant Pests and Diseases, Faculty of Agriculture, Brawijaya University, Malang, from August 2020 to July 2021. Biological observations, including the life cycle, lifespan, and fecundity, were made to gather demographic data. Parameters for demographic analysis included the gross reproduction rate (GRR), net reproduction rate (R0), intrinsic rate of increase (r), and generation time (T). The results showed that the nymphal stages lasted 2.30, 2.17, 2.28, and 2.09 days for the first to fourth instars, respectively. The mean life cycle duration was 8.85 days, with a total fecundity of 21.04 offspring per female adult. Meanwhile, the average lifespan of M. persicae was 11.93 days. Demographic statistics for M. persicae on chili showed a GRR of 51.71 individuals per generation, an R0 of 14.41 individuals per female per generation, an r of 0.38 individuals per female per day, and a T of 16.22 days.

Life table and cold tolerance of laboratory-reared Penthaleus major (Acari: Penthaleidae).

Penthaleus major (Dugés) is a significant agricultural pest that attacks various pasture, vegetable, and crop plants. Temperature plays a critical role in the life history of P. major. However, there is limited understanding of its life table at different temperatures and cold tolerance. This study aimed to elucidate the performance of P. major by constructing life tables at 6, 9, 12, 15, 18, 21, and 24 °C. The results showed that P. major successfully developed at 9‒21 °C. However, no adults emerged at 6°C, and no eggs hatched at 24 °C. The highest intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and gross reproductive rate (GRR) were observed at 12 °C. The supercooling point (SCP) exhibited significant variations at different developmental stages. The highest SCP (‒9.75 °C) was recorded in 10-day-old female adults, while the lowest SCP (‒24.37 °C) was observed in larvae. For female adult mites of 2, 6, and 10 days old, the low lethal temperatures (LLT50) were ‒14.63, ‒12.03, and ‒11.08 °C, respectively. This study provided valuable insights for modeling and predicting the population dynamics of P. major in the field and offered implications for developing successful management strategies.

Population Demographics of Helopeltis bradyi Waterhouse (Hemiptera: Miridae) from Three Different Locations

Helopeltis bradyi Waterhouse has been reported to attack tea plantations in Batang District and cocoa plantations in Sleman District and Kulon Progo District. Information about the life parameters of H. bradyi reared using alternative feed cucumbers in the laboratory helps pest management efforts. This study aimed to determine the life demography of H. bradyi from two plants and three different locations. The study was conducted with cohort observations consisting of gross reproduction rate (GRR), net reproduction rate (Ro), intrinsic growth (r), average generation length (T), and population doubling time (DT) of three populations of H. bradyi. Results showed that there were differences in living individuals (ax), mortality, and life duration of the three H. bradyi populations. The survival type of the three populations of H. bradyi was classified as type IV. The survival of the three H. bradyi populations were influenced by their ability to adapt to new environments. From the three populations of H. bradyi observed, Sleman population survived longer because they had adapted to the rearing environment and were able to maintain the population numbers for two generations. Demographic parameters of H.bradyi from Sleman showed gross reproduction rate (GRR) of 88 individuals/generation, net reproduction rate (Ro) of .97 individuals/parents/generation, the increase in population rate (r) of 0.02 individuals/species/day, extended duration (T) of 39.50 days, and doubling time (DT) of 40.49 days.

Frankliniella occidentalis pathogenic fungus Lecanicillium interacts with internal microbes and produces sublethal effects

Frankliniella occidentalis (Thysanoptera: Thripidae) is a pest that feeds on various crops worldwide. A prior study identified Lecanicillium attenuatum and L. cauligalbarum as pathogens of F. occidentalis. Unfortunately, the potential of these two entomopathogenic fungi for the biocontrol of F. occidentalis has not been effectively evaluated. The internal microbes (endosymbionts and the gut microbiota) of insects, especially gut bacteria, are crucial in regulating the interactions between the host and intestinal pathogens. The role of thrips internal microbes in the infection of these two entomopathogenic fungi is also unknown. Therefore, biological control of thrips is immediately needed, and to accomplish that, an improved understanding of the internal microbes of thrips against Lecanicillium infection is essential. The virulence of the two pathogenic fungi against F. occidentalis increased with the conidia concentration. Overall, the LC50 of L. cauligalbarum was lower than that of L. attenuatum, and the pathogenicity degree was adult > pupa > nymphs. The activities of protective enzymes include superoxide dismutase (SOD), catalase (CAT), peroxidase (POD); detoxification enzymes include polyphenol oxidase (PPO), glutathione s-transferase (GSTs), and carboxylesterase (CarE); hormones include ecdysone and juvenile hormone; and the composition and proportion of microorganisms (fungi and bacteria) in F. occidentalis infected by L. cauligalbarum and L. attenuatum have changed significantly. According to the network correlation results, there was a considerable correlation among the internal microbes (including bacteria and fungi), enzyme activities, and hormones, which indicates that in addition to bacteria, internal fungi of F. occidentalis are also involved in the L. cauligalbarum and L. attenuatum infection process. In addition, the development time of the surviving F. occidentalis exposed to L. cauligalbarum or L. attenuatum was significantly shorter than that of the control group. Furthermore, the intrinsic rate of increase (rm), finite rate of increase (λ), net reproductive rate (R0), mean generation time (T), and gross reproductive rate (GRR) were significantly lower in the treatment groups than in the control group. L. attenuatum and L. cauligalbarum have biocontrol potential against F. occidentalis. In addition to bacteria, internal fungi of F. occidentalis are also involved in the infection process of insect pathogenic fungi. Disruption of the internal microbial balance results in discernible sublethal effects. Such prevention and control potential should not be ignored. These findings provide an improved understanding of physiological responses in thrips with altered immunity against entomopathogenic fungal infections, which can guide us toward the development of novel biocontrol strategies against thrips.

A comparative study of two-sex life table parameters of Orius laevigatus fieber (Hemiptera: anthocoridae) on two mealybug species, Planococcus citri Risso, and P. solenopsis Tinsley (Hemiptera: Pseudococcidae)

BackgroundAugmentative biological control is a crucial component of Integrated Pest Management, and Orius laevigatus Fieber (Hemiptera: Anthocoridae) is an important predator used commercially. However, the two-sex life table parameters of O. laevigatus on Planoccocus citri Risso, and P. solenopsis Tinsley (Hemiptera: Pseudococcidae) have not been fully characterised. This study aimed to assess the potential of P. citri and, P. solenopsis as prey for mass-rearing the predatory bug. To accomplish this, three different prey items (individuals of P. citri, P. soleneopsis, and eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)) were used to determine the life table parameters of the minute pirate bug.ResultsDaily and total fecundity, adult longevity, APOP, TPOP, and pre-adult periods were calculated in this study. The results showed that daily fecundity was 7.4 ± 0.10, 4.41 ± 0.08, 3.47 ± 0.08, and adult longevity was 20.9 ± 0.47, 15.17 ± 0.31, 14.03 ± 0.39 on E. kuehniella, P. solenopsis and P. citri, respectively. Net reproduction rate (R0) was 57.23 ± 11.35, 17.27 ± 3.57, 11.05 ± 2.30, and the intrinsic rate of increase (r) was 0.172 ± 0.009, 0.084 ± 0.006, 0.069 ± 0.006 on E. kuehniella, P. soleneopsis, and P. citri, respectively. Additionally, finite rate of increase (λ), gross reproductive rate (GRR), and mean generation time (T) were calculated on the three tested prey.ConclusionOverall, the results showed that eggs of E. kuehniella were the most suitable prey for the mass-rearing of O. laevigatus. Although P. citri and P. solenopsis had worse results than E. kuehniella, P. solenopsis may still have potential, and O. laevigatus could potentially be used against this pest with further studies in laboratory and field conditions.

The effects of a novel botanical pesticide on demographic and some biochemical parameters of Panonychus citri (McGregor)

ABSTRACT Panonychus citri (McGregor) is one of the most destructive pests of citrus trees. Its control is difficult because it has developed resistance to some synthetic pesticides. GC-mite is a novel botanical pesticide based on cottonseed, clove, and garlic oils that has shown the potential to control tetranychid mites. This study aimed to evaluate the effects of sublethal concentrations of GC-mite on the life history and biochemical parameters of P. citri. Age-stage life table procedure was used to evaluate the effects of two sublethal concentrations (LC20 = 59.40 μg ml−1 and LC30 = 78.66 μg ml−1) of GC-mite on the development, longevity, and reproduction of P. citri. The biochemical analysis included the content of lipids, carbohydrates and glycogen, esterase, and glutathione S-transferase (GST) activities. The developmental time of treated mites with LC30 was significantly longer than the control but the adult longevity and oviposition days of P. citri treated with both sublethal concentrations decreased. The total fecundity of treated mites decreased with increasing GC-mite concentration applied. The life table analysis showed that sublethal concentrations of GC-mite significantly affected gross reproductive rate (GRR), net reproductive rate (R 0), intrinsic rate of increase (r), and mean generation time (T). The estimated values of r were significantly lower than the control in LC20 (0.130 day−1) and LC30 (0.117 day−1). The lipids, carbohydrates and glycogen contents as well as esterase and GST activities were significantly lower in mites treated with LC30 concentration, but no significant effect was found in mites treated with LC20 and control. These results suggest that sublethal concentrations of GC-mite had significant effects on both demographic and biochemical parameters of P. citri.

Life history traits and population parameters of the predatory mite Euseius scutalis (Acari: Phytoseiidae) fed on Tetranychus turkestani (Acari: Tetranychidae) and pollen from three different plants

Development, reproduction, and demographic parameters of the predatory mite Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) were determined in the laboratory at 25±1 °C, with a 16L:8D photoperiod and 60 ±5% RH, to evaluate its response to four different diets: Tetranychus turkestani Ugarov and Nikolskii (Acari: Tetranychidae), caster bean pollen, date palm pollen, and hopbush pollen. Male and female mites raised on T. turkestani had a shorter mean pre-adult duration than those grown on date palm, castor, and hopbush pollen. Pre-adult mortality was found to be greater in either the larval stage or protonymphal stage than other stages. The highest and lowest pre-adult mortality rates were recorded on castor bean pollen (31.87%) and T. turkestani (2.94%), respectively. The total pre-oviposition periods (TPOP) on hopbush and castor bean pollen were significantly longer than those on T. turkestani and date palm pollen. The highest egg production and oviposition period were determined when T. turkestani were provided as diet. Overall, the individuals lived considerably longer when provided with T. turkestani and hopbush pollen than the two other diets. The gross reproductive rate (GRR) and net reproductive rate (R<sub>0</sub>) on T. turkestani were greater than the values attained on other diets. The highest intrinsic (r) and finite rates of increase (λ) were found to be 0.2537 and 1.2888 on T. turkestani, respectively. However, R<sub>0</sub>, GRR, r, and λ were almost similar between all pollen diets tested. In general, all diets tested in this study were adequate for development and oviposition in E. scutalis, but T. turkestani was the most favorable diet.

Lethal and sublethal effects of lambda-cyhalothrin on Aphis fabae (Scopoli, 1763), Myzus persicae (Sulzer, 1776) and Acyrthosiphon pisum (Harris, 1776) (Hemiptera: Aphididae)

In this study, sublethal doses of lambda-cyhalothrin to the species Aphis fabae (Scopoli, 1763), Myzus persicae (Sulzer, 1776) and Acyrthosiphon pisum (Harris, 1776) (Hemiptera: Aphididae) were determined, and the effects of these doses on the life cycles of the species were revealed and evaluated. The lethal effects of different concentrations (0.3125, 0.625, 1.25, 2.5, 5, 10 and 20 µL L-1) prepared by distillated water of lambda-cyhalothrin on the species were determined according to Abbott. Based on the results obtained, the effects of LC30 and LC40 concentrations of the insecticide on the life cycles of the species were determined. The insecticide caused different mortality rates in the species. The sublethal concentrations of the insecticide were found to be effective for the life cycles of the species. In all three species, intrinsic rate of increase (rm), net reproduction rate (R0) and gross reproduction rate (GRR) values were found to decrease when insecticide was applied. The results will provide guidance to researchers working in this specific field. However, it would be beneficial to replicate this study under field conditions to obtain clear information.