Preoviposition Period Research Articles

Age–Stage, Two-Sex Life Table Analysis of Riptortus pedestris (Hemiptera: Alydidae) Across Different Soybean Varieties

Riptortus pedestris (Hemiptera: Alydidae) is an economically important pest of soybeans, significantly affecting their quality and market value. This study aims to evaluate the adaptability of R. pedestris to different soybean varieties and provide a foundation for selecting resistant varieties and developing effective integrated pest management strategies. Seven widely planted varieties (Beidou No. 3, Jiyu 47, Jiyu No. 80, Jiyu No. 90, Jiyu 203, Kangxianchong No. 6, and Kangxianchong 12) were selected for testing, and the developmental and population parameters of R. pedestris were measured using an age–stage, two-sex life table method. Notable differences were found in the developmental period, female longevity, and total preoviposition period (TPOP) of R. pedestris across diverse varieties. For those feeding on Kangxianchong 12, the nymph stage (14.73 ± 0.11 days), total longevity (37.35 ± 1.12 days), total female longevity (38.83 ± 1.80 days), and fecundity (38.86 ± 3.27 eggs per female) were all remarkably longer than on the other varieties. Additionally, the intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and average generation time (T) of R. pedestris varied significantly between soybean varieties. The lowest r (0.0789 ± 0.0075 per day) and λ (1.0821 ± 0.0081 per day) values were recorded for Kangxianchong No. 6, while the highest were for Jiyu 47 (r = 0.0933 ± 0.0070 per day, λ = 1.0978 ± 0.0076 per day). The R0 and T values for R. pedestris on Kangxianchong 12 (R0 = 16.33 ± 3.24 offspring per female, T = 31.18 ± 0.79 days) were remarkably higher than those of the other six varieties, suggesting that Kangxianchong 12 and Jiyu 47 are preferred hosts, whereas Kangxianchong No. 6 is less preferred. These results provide valuable insights for optimizing soybean cultivation and managing R. pedestris.

Investigations on Biology and Life Cycle of Pear Psylla, Cacopsylla pyricola Foerster

Pear psylla (Cacopsylla pyricola Foerster) is a significant pest of pear trees (Pyrus communis), causing extensive damage to pear orchards through feeding and the secretion of honeydew. A laboratory study was conducted at SKUAST - Kashmir to examine the biology and life cycle of Pear psylla, Cacopsylla pyricola Foerster under controlled conditions (32±2°C, 12:12 photoperiod, and 65±5 % RH). The results revealed that the incubation period lasted for 0.36 days. The insect undergone five nymphal instars, with a total nymphal period of 0.72 days. Adult psyllids exhibited a pre-oviposition period of 0.31 days, followed by an oviposition period of 1.34 days, with fecundity ranging from 400 to 650 eggs/female. Male psyllids lived slightly longer (62.55 days) than females (61.35 days). The study contributes valuable data for better understanding the biology of pear psylla, facilitating more effective pest management strategies in pear-growing regions.

Bionomics of Earhead Bug Leptocorisa acuta Thunberg (Coreidae: Hemiptera) Infesting Rice

Biology of rice earhead bug, Leptocorisa acuta (Thunberg) carried out at Laboratory of Department of Entomology, N. M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat on rice (Gujarat Rice-11) during kharif-2023. Eggs were dark brown with an average length and breadth of 1.28±0.05 mm and 0.85±0.06 mm, respectively. The incubation period varied from 5 to 7 days with an average of 6.07±0.78 days and the average hatching percentage was 81.22±14.93 per cent. There were five nymphal instars in the life cycle of L. acuta. The average developmental periods of the first, second, third, fourth and fifth nymphal instars were 2.80±0.41, 1.67±0.55, 1.87±0.57, 2.83±0.53 and 4.23±0.63 days, respectively. The total nymphal period was an average of 13.77±0.86 days. The total developmental period (egg + nymph) was found to be an average of 19.83±1.39 days. The average adult period was 23.50±7.69 days. The average pre-oviposition, oviposition and post-oviposition periods lasted for 4.87±1.50, 9.03±3.36 and 15.63±3.20 days, respectively. The average longevity for male and female adults lasted for 17.47±2.83 and 29.53±3.91 days, respectively. The female laid an average of 53.96±31.90 eggs. The total life cycle from egg to adult was an average of 42.67±7.38 days.

Effects of continuous and transgenerational rearing in peanut leaves on the performance and enzyme activity of Spodoptera frugiperda (Lepidoptera: Noctuidae).

The invasive fall armyworm (FAW), Spodoptera frugiperda, is a polyphagous pest that significantly threatens crops worldwide. FAW may undergo adaptation, enhancing its ability to infect specific plant hosts. However, there is limited knowledge on this topic. After 8 generations of constant rearing on peanut leaves, the performance and enzyme activities of FAW were investigated in this study. Compared to FAW fed on the peanut cultivars 'Fuhua 8' and 'Quanhonghua 1' for 2 generations, those grown on leaves for 5 to 8 generations had significantly shorter pre-adult development times and total preoviposition periods. Fecundity also increased significantly, resulting in an overall improvement in population fitness as measured by demographic parameters. However, the F2 generation of FAW fed on corn leaves outperformed the F8 generation of FAW fed on peanut leaves. In the F2 generation, the FAW peanut population exhibited 30-55% supernumerary larval molts, which decreased substantially in the F5 and F8 generations. Notably, supernumerary larval molts displayed pupation and emergence rates comparable to normal larvae, regardless of the peanut cultivar or rearing generation. The activities of lipase and acetylcholinesterase increased significantly from the F2 to F8 generations, showing substantial negative and positive correlations with larval development time and fecundity, respectively. In conclusion, FAW demonstrated inferior performance on peanut leaves compared to corn leaves, despite its performance was significantly improved after 5 to 8 generations of acclimation. These results suggest that corn will continue to be the primary target crop for FAW in China.

Exposure to Cyantraniliprole Adversely Impacts Fitness of Harmonia axyridis: Acute Toxicity and Sublethal Effects on Development, Fecundity and Antioxidant Responses.

Extensive utilization of pesticides and their persistent residues inadvertently pose threats to the effectiveness and fitness of biocontrol agents in agroecosystems. However, these ecological consequences are generally disregarded when executing integrated pest management strategies (IPM). Cyantraniliprole (CNAP) serves as a wide-spectrum diamide insecticide and its sublethal effects have been well characterized on multiple insect pests, whereas its impacts on beneficial natural enemies remain unfathomed. Herein we exposed Harmonia axyridis, a predacious generalist, to lethal and sublethal concentrations of CNAP via dipping treatment (egg stage) and topical applications (1st-instar stage + adult stage). The acute toxicity tests revealed that LC50 of CNAP were 90.11, 86.11 and 240.50 mg/L against embryos, 1st instar nymphs and female adults, respectively, with safety factors ranging from 1.14 to 5.34, suggesting its medium toxicity for H. axyridis and larval stage was the most susceptible. The embryonic, larval and pupal durations of coccinellids ecdysed from CNAP-treated eggs and 1st instars were all elongated under sublethal concentrations, of which LC30 triggered more pronounced and significant retardations relative to control. Besides, exposed coccinellids displayed substantially diminished pupal mass and pupation rate, most notably for insects molted from the 1st-instar stage upon CNAP sublethal treatments. With respect to reproductive performance, LC10 and LC30 of CNAP all significantly suppressed female fecundity, as evidenced by reduced vitellin content, a prolonged pre-oviposition period (POP), mitigated laid eggs and the egg hatching rate. Specifically, there existed positive correlations between vitellin level (Vn) and number of eggs deposited by per female, indicative of CNAP affecting fecundity by regulation of Vn. In addition, the antioxidant system was also profoundly disrupted by CNAP, with compromised POD activity at different concentrations over time and induced hormesis of SOD/CAT activities post LC10 exposure. Activities of SOD and TAC were enhanced to exert protective functions during the first 48 h, while defense collapsed at 72 h following LC30 treatments that depleted all enzymatic activities. We speculated that fitness trade-offs may occur between reproductive capacity and antioxidant defenses to sustain physiological homeostasis in response to CNAP stress. Collectively, this study evaluated the ecological risk of CNAP and unmasked its adverse implications for overall fitness of H. axyridis, which highlighted rational application of agrochemicals to conserve biocontrol agents when implementing IPM strategies for sustainable pest control.

Impact of dietary restriction on development, mating, and reproduction in the natural predator Pardosa pseudoannulata.

Dietary restriction-influenced biological performance is found in many animal species. Pardosa pseudoannulata is a dominant spider species in agricultural fields and is important for controlling pests. In this study, three groups - a control group (CK group), a re-feeding group (RF group), and a dietary restriction group (RT group) - were used to explore development, mating, reproduction, and the expression levels of Vg (vitellogenin) and VgR (vitellogenin receptor) genes in the spider. The findings indicated that when subjected to dietary restriction, the carapace size, weight of the spiderlings, and weight of the adults exhibited a decrease. Furthermore, the preoviposition period and egg stage were observed to be prolonged, while the number of spiderlings decreased. It was also observed that re-feeding reduced cannibalism rates and extended the preoviposition period. Dietary restriction also affected the expression of the Vg-3 gene in the spider. These results will contribute to the understanding of the impact of dietary restriction in predators of pest control, as well as provide a theoretical foundation for the artificial rearing and utilisation of the dominant spider in the field.

Lethal and sublethal concentrations spirodiclofen stress may increase the adaptation of Panonychus citri (Acari: Tetranychidae).

Panonychus citri is one of the most destructive pests in citrus orchards, exhibiting varying degrees of tolerance to numerous insecticides, such as spirodiclofen. To effectively manage pests, this study explores the response of P. citri to spirodiclofen stress from the perspectives of life history, enzymatic parameters, and reproduction. The effects of two concentrations (LC30 and LC50) of spirodiclofen on the biological parameters of P. citri were evaluated by the life table method. The results showed that the development duration, fecundity, oviposition days, and lifespan were shortened, though the pre-oviposition period of two treatments was prolonged in comparison with the control. A significant decrease was recorded in the net reproductive rate (R0) and the mean generation time (T) for the two treatments. Nevertheless, the intrinsic rate of increase (r) and the rate of increase (λ) were not significantly affected in the LC30 treatment, whereas they declined in the LC50 treatment. The enzyme activity assay resulted in higher activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and carboxylesterase (CarE), among the treatments than the control. In contrast, the treatments recorded lower cytochromeP450 (CYP450) and Glutathione S-transferase (GST) activities than the control. Furthermore, the study detected that relative mRNA expression of Vitellogenin (Vg) and Vitellogenin receptor (VgR) for two treatments were lower than the control. In summary, two concentrations of spirodiclofen inhibited progeny growth and fecundity of P. citri. Additionally, the results of this study may support further research on tolerance of P. citri in response to spirodiclofen stress.

Assessment of Biological Characteristics of Red Spider Mite (Tetranychus urticae) Koch on Brinjal

Red spider mite, Tetranychus urticae Koch passed through five stages viz., egg, larva, protonymph, deutonymph and adult with three short resting stages known as quiescent stages which termed as nymphochrysalis, deutochrysalis and teleiochrysalis. The incubation period of egg was 3.28 ± 1.10 days with 0.13 ± 0.01 mm diameter in size. The average length and breadth of larva, nymphochrysalis, protonymph, deutochrysalis, deutonymphs, teleiochrysalis, adult male and adult female stage were 0.14 ± 0.01 and 0.10 ± 0.01; 0.19 ± 0.01 and 0.12 ± 0.01; 0.20 ± 0.01 and 0.12 ± 0.01; 0.24 ± 0.02 and 0.13 ± 0.01, 0.29 ± 0.02 and 15 ± 0.02, 0.35 ± 0.03 and 0.18 ± 0.01, 0.43 ± 0.04 and 0.19 ± 0.01; and 0.47 ± 0.02 and 0.22 ± 0.01 mm, respectively. The mean duration of male and female larva, nymphochrysalis, protonymph, deutochrysalis, deutonymphs, teleiochrysalis and adult was 2.07 ± 0.73 and 2.36 ± 0.22, 0.58 ± 0.32 and 0.68 ± 0.22, 2.23 ± 0.35 and 2.92 ± 0.81, 0.70 ± 0.35 and 0.76 ± 0.39, 2.12 ± 0.44 and 2.56 ± 0.51, 0.77 ± 0.19 and 0.87 ± 0.37 and 7.12 ± 0.93 and 11.08 ± 0.86 days, respectively. Female of T. urticae occupied 2.48 ± 0.96, 5.32 ± 0.99 and 2.35 ± 0.84 days as pre-oviposition, oviposition and post-oviposition period, respectively. Total life period of male and female was 19.14 ± 2.06 and 23.85 ± 1.65 days, respectively. The average fecundity and hatching percentage were 47.60 ± 6.13 days and 91.11 ± 4.14 per cent, respectively with 1 : 2.50 sex ratio.

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.

Reproductive parameters of a new biocontrol agent, Eupeodes americanus (Diptera: Syrphidae) and comparison with the commercialized Aphidoletes aphidimyza (Diptera: Cecidomyiidae).

The American hoverfly Eupeodes americanus (Wiedemann) (Diptera: Syrphidae) is an aphidophagous predator during its larval stage and is currently being evaluated for inclusion in biocontrol programs as a new biocontrol agent. However, little is known about its reproductive aptitudes. The objective of the present study was to determine the reproductive parameters of E. americanus and to compare them with those of a commercialized and widely used biological control agent for aphids, the aphid midge Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae). The preoviposition period, oviposition period, adult longevity, lifetime and daily fecundity, egg hatching rate, and fertility were determined for E. americanus females and compared to those of A. aphidimyza. Trials were conducted under laboratory conditions in rearing cages on the broad bean plant Vicia faba L. (Fabaceae), infested with pea aphids Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). The results revealed that the preoviposition period, oviposition period, and adult longevity were significantly longer in E. americanus than in A. aphidimyza. The daily fecundity and egg-hatching rate were similar in both species. However, lifetime fecundity and fertility were considerably higher in E. americanus than in A. aphidimyza. This study demonstrates that the reproductive capacity of E. americanus is clearly superior to that of A. aphidimyza and therefore supports its inclusion in the aphid pest management program as a new biocontrol agent.

Life history parameters of Ectropis grisescens (Lepidoptera: Geometridae) in different Wolbachia infection states.

Wolbachia, a prevalent intracellular symbiotic bacterium in insects, plays a significant role in insect biology. Ectropis grisescens (Warren; Lepidoptera: Geometridae) is a devastating chewing pest distributed in tea plantations throughout China. However, it is unclear how Wolbachia titers affect the fitness and reproduction of E. grisescens. In this study, the impacts of 3 different infection lines, naturally Wolbachia-infected, Wolbachia-uninfected, and Wolbachia transinfected, regarding the life history traits of E. grisescens, were evaluated using the age-stage, 2-sex life table. Wolbachia infection shortened preadult duration and preoviposition periods and increased the fecundity, net reproductive rate, and finite rate of increase. Meanwhile, population projection indicated that E. grisescens population size with Wolbachia infection can increase faster than without. These results indicate that Wolbachia plays a regulatory role in the fitness of E. grisescens. It is also noted that the life history parameters of E. grisescens may positively correlate with Wolbachia titers. These findings could aid in pest management in tea gardens.

Assessing performance of Amblyseius swirskii as a predatory mite of Tetranychus urticae and Frankliniella occidentalis: life table and foraging behaviour studies

ABSTRACT Life table parameters of Amblyseius swirskii when Frankliniella occidentalis and Tetranychus urticae were offered solely as diet were investigated. The switching behaviour of this predator was studied on F. occidentalis in the presence of spider mites. The data showed that feeding on the spider mite resulted in significantly longer developmental time compared to thrips. We found a significant effect of prey on the total life span, adult pre-oviposition period (APOP), and total pre-oviposition period (TPOP) of the predatory mite. The length of the oviposition period and the number of laid eggs per female were not affected by the kind of the offered prey. None of population growth parameters was affected by the type of diet except for mean generation time (T). Predators fed on spider mite had a longer T than those reared on thrips. Furthermore, our data illustrated a negative switching in the behaviour of A. swirskii when T. urticae and F. occidentalis were present. In other words, the predator switched from the abundant prey to the rarer prey. The results of this study are needed to understand and forecast the performance of A. swirskii in greenhouse environments where both T. urticae and F. occidentalis can be present.

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.

Particulate matter hinders the development and reproduction of predatory mites of Euseius finlandicus (Acariformes: Phytoseiidae)

The foliage of the small-leaved lime (Tilia cordata) is characterised by the nerve axils being grown by non-glandular trichomes, which trait contributes to the enhanced retention of the particulate matter (PM). This fact may disturb the ecological service of T. cordata related to the structure of its leaves, which is to provide acarodomatia (micro-shelters) for the predatory mites of the Phytoseiidae family. Phytoseiids are natural enemies of a variety of plant pests, widely applied in integrated pest management (IPM). Their occurrence is largely related to acarodomatia in which these mites hide, feed, reproduce, and develop. For the first time, the influence of PM deposition within spaces typically occupied by phytoseiids is investigated. Experimental populations of Euseius finlandicus were reared on T. cordata leaves in the progressive PM-pollution. The results showed that the values of life table parameters of the predator depended significantly on the level of PM deposition on leaves. Contrary to clean leaves from the control, the medium and high contamination intensities significantly reduced the daily (by 47% and 70%, respectively) and the total fecundity (by 62% and 77%, respectively) of females which, in turn, resulted in a decreased net reproductive rate (by 67% and 81%, respectively), intrinsic rate of increase (by 40% and 55%, respectively) and finite rate of increase (by 8% and 10%, respectively) of E. finlandicus. The pre-ovipositional period was prolonged, while the oviposition duration was shortened and the mites matured longer. In high pollution level the mortality of phytoseiids was boosted by 19% and some females were observed with pollutant lumps adhered to the idiosoma. Also, significant shares of juvenile forms (13%) and adult females (25%) made attempts to escape from highly contaminated experimental arenas. The implications of PM retention on the shelter vegetation are discussed in the context of IPM and ecological services.

Leaf beetle Phyllotreta striolata (Coleoptera: Chrysomelidae): Biology and infestation on Chinese flowering cabbage Brassica rapa var. parachinensis in Bogor, West Java, Indonesia

Abstract. Laia DAS, Maryana N, Winasa IW. 2024. Leaf beetle Phyllotreta striolata (Coleoptera: Chrysomelidae): Biology and infestation on Chinese flowering cabbage Brassica rapa var. parachinensis in Bogor, West Java, Indonesia. Biodiversitas 25: 3099-3105. Chinese flowering cabbage (Brassica rapa var. parachinensis L.) holds significant economic value and provides essential nutrition. Bogor District, a primary region for vegetable production in Indonesia, faces a severe issue due to the leaf beetle Phyllotreta striolata Fabricius 1803 infestation on Chinese flowering cabbage plants. However, research on this pest in Indonesia is still limited. Observations on the biological aspects of P. striolata involved collecting and identifying adult P. striolata from Chinese flowering cabbage fields, along with biological observations focusing on the beetle's morphology and developmental stages. Population calculations of adult beetles and evaluation of P. striolata infestation intensity on Chinese flowering cabbage plants were conducted in four sub-districts in Bogor District. The average life cycle of this beetle was 27.15 days. The study revealed that the adult stage lasted an average of 119.10 days, with an average preoviposition period of 3.08 days. Adult populations tended to decrease with the age of Chinese flowering cabbage plants due to environmental factors and food source availability. Infestation intensity varied across locations, with Leuwimalang showing the lowest intensity (23.56%) and Laladon the highest (48.76%). These differences suggest that the environment in Leuwimalang may support the resistance of Chinese flowering cabbage plants to leaf pest attacks.

The Food Source and Gut Bacteria Show Effects on the Invasion of Alien Pests-A Case of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae).

How alien pests invade new areas has always been a hot topic in invasion biology. The spread of the Bactrocera dorsalis from southern to northern China involved changes in food sources. In this paper, in controlled conditions, we take Bactrocera dorsalis as an example to study how plant host transformation affects gut bacteria by feeding it its favorite host oranges in the south, its favorite host peaches and apples in the north, and feeding it cucumbers as a non-favorite host plant, thereby further affecting their fitness during invasion. The result showed that, after three generations of feeding on cucumbers, Bactrocera dorsalis took longer to develop as a larva while its longevity and fecundity decreased and pre-adult mortality increased. Feeding it cucumbers significantly reduced the overall diversity of gut microbiota of Bactrocera dorsalis. The relative abundance of Enterobacter necessary for survival decreased, while the Empedobacter and Enterococcus increased, resulting in decreased carbohydrate transport and metabolism and increased lipid transport and metabolism. Feeding Bactrocera dorsalis Empedobacter brevis and Enterococcus faecalis resulted in a 26% increase in pre-adult mortality and a 2-3 d increase in adult preoviposition period (APOP). Additionally, Enterococcus faecalis decreased the longevity of female and male adults by 17 and 12 d, respectively, and decreased fecundity by 11%. We inferred that the shifted plant hosts played an important role in posing serious harm to Bactrocera dorsalis invading from the south to the north. Therefore, after an invasion of Bactrocera dorsalis into northern China, it is difficult to colonize cucumbers for a long time, but there is still a risk of short-term harm. The findings of this study have established that the interactions between an insect's food source and gut bacteria may have an important effect on insect invasions.

Age-Stage, Two-Sex Life Table of Atractomorpha lata (Orthoptera: Pyrgomorphidae) at Different Temperatures.

Atractomorpha lata Motschoulsky (Orthoptera: Pyrgomorphidae) has recently emerged as an important agricultural pest in China. Understanding the impact of temperature on its developmental period is crucial for predicting its population dynamics. This study systematically observed the biological characteristics of A. lata at five temperatures (16, 20, 24, 28, and 32 °C) using the age-stage, two-sex life table method. The effects of temperature on the developmental period, survival rate, and fecundity of A. lata were studied using fresh bean leaves as host. The results demonstrated that as temperature increased from 16 °C to 32 °C, the developmental period, preadult time, adult longevity, adult preoviposition period (APOP), and total preoviposition period (TPOP) significantly decreased. The developmental threshold temperatures for various stages were calculated, ranging from 10.47 °C to 13.01 °C, using the linear optimal method. As temperature increased, both the intrinsic rate of increase (r) and the finite rate of increase (λ) also increased, while the mean generation time (T) decreased. The optimal values of the net reproductive rate (R0 = 54.26 offspring), gross reproductive rate (GRR = 185.53 ± 16.94 offspring), and fecundity (169.56 ± 9.93 eggs) were observed at 24 °C. Similarly, the population trend index (I) for A. lata peaked at 24 °C (61.64). Our findings indicate that A. lata exhibits its highest population growth rate at 24 °C, providing a scientific basis for predicting its population dynamics in the field.

Sublethal effects of a spiromesifen and abamectin combination on Tetranychus urticae (Acari: Tetranychidae) and its predators Phytoseiulus persimilis and Amblyseius swirskii (Acari: Phytoseiiidae).

The two-spotted spider mite, Tetranychus urticae Koch (TSSM), is an important cosmopolitan pest of agricultural crops that is often managed in greenhouses by augmentation of predatory mites in combination with acaricides. Here we examined the transgenerational effects of low lethal concentrations of a widely-used acaricide, Oberon Speed® (a combination of spiromesifen and abamectin), on the life history traits and population growth of T. urticae and two of its predators, Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). The concentrations employed corresponded to the LC10, LC20 and LC30 values estimated for TSSM protonymphs 48h post-exposure in a topical bioassay, which yielded an LC50 value of 207.2ppm. Parental exposure of TSSM to all three low concentrations increased the total developmental time of progeny; both the LC20 and LC30 treatments reduced adult longevity and number of oviposition days, but only the LC30 treatment increased the preoviposition period. Similarly, both the LC20 and LC30 treatments significantly reduced life table parameters (r, R0, λ, and GRR), and increased generation time (T) and population doubling time (DT). Although maternal exposure to the acaricide had various impacts on progeny life history, A. swirskii was less affected than P. persimilis, suggesting the former species would be more compatible for integration with Oberon Speed® for control of T. urticae in greenhouse vegetable production.

Oviposition biology and seed damage by Smicronyx lutulentus Dietz (Coleoptera: Curculionidae), a biological control agent of Parthenium hysterophorus L. (Asteraceae) in South Africa

The seed-feeding weevil Smicronyx lutulentus Dietz (Curculionidae) was released in South Africa in 2015 to supplement the biological control programme against the invasive annual weed Parthenium hysterophorus L. (Asteraceae). Larval feeding within young, developing ovules and larval-induced abortion of adjacent seeds within the flowerheads causes seed destruction, augmenting low levels of natural seed abortion. We studied female fecundity in a glasshouse trial, to identify critical periods in oviposition and inform mass-rearing and field release protocols. Newly emerged mated females displayed a pre-oviposition period of 1–2 weeks, a peak in oviposition after 7–8 weeks and a lifetime fecundity of 324–446 eggs. We also studied the relationship between weevil density and seed damage during two separate glasshouse trials, to facilitate predictions of seed damage under field conditions. Plants exposed to 15 mating pairs of weevils harboured substantially higher proportions of larval-damaged flower buds (75 %) than plants with five pairs (45–56 %) or a single pair (19 %). Larval progeny from five adult pairs caused significantly higher seed inviability (38 %) than progeny from a single pair (14 %), versus the weevil-free control (5 %). Progeny from 15 pairs damaged 30 % of developing seeds, potentially causing up to 60 % seed inviability due to enhanced abortion of neighbouring seeds. Although ≥5 females per plant caused appreciable seed damage, the proportions of unexploited new buds (25–55 %) versus buds with multiple occupancy (≥2 larvae; 35–47 %) indicate the importance of floral phenology in oviposition site selection, as flowerbuds of 2–3 mm are preferred. Although progeny from five females per plant could cause up to 30 % seed reduction, within a week of oviposition, higher densities are required to limit the entry of viable seeds into the soil seed banks.