Development, Reproduction, and Life Table Parameters of the Foxglove Aphid, Aulacorthum solani Kaltenbach (Hemiptera: Aphididae), on Soybean at Constant Temperatures

Survival, development, and reproduction of Aulacorthum solani (Hemioptera: Aphididae) fed on Persicaria lapathifolia

The foxglove aphid, Aulacorthum solani (Kaltenbach), is a polyphagous economic pest. In this study, A. solani were fed on detached leaves of dockleaf knotweed, Persicaria lapathifolia (L.) Delarbre. Survival, development, and reproduction were studied at constant temperatures of 17, 20, 23, 26, 29, and 32 °C. These data were compared with those of controls fed on Glycines max (L.) Merrill. At 17, 20, 23, and 26 °C, the survival rate of A. solani adults fed on P. lapathifolia were lower than those fed on G. max; the adult longevity, aphid total longevity, and reproduction period were shorter. At 20, 23, and 26 °C, the adult fecundity, intrinsic rate of increase, finite rate of increase, and net reproductive rate of A. solani fed on P. lapathifolia were smaller than those fed on G. max. At 29 °C, the survival rate of A. solani adults fed on P. lapathifolia were higher than those fed on G. max; the adult longevity and aphid total longevity were longer. These results are consistent with our finding that A. solani feed on P. lapathifolia, which is important for studying the host adaptability of A. solani.

Feeding behavior, life-history traits, and settling preference of Aulacorthum solani (Hemiptera: Aphididae) on resistant and susceptible soybeans

Foxglove aphid, Aulacorthum solani Kaltenbach (Hemiptera: Aphididae), is a major pest worldwide. It can infest various crops, including soybean, and reduce yields. The use of insect-resistant cultivars can effectively manage pests. Dowling is a soybean cultivar that can control Aphis glycines through antibiosis and antixenosis. In this study, we investigated the feeding behavior of A. solani using electropenetrography (EPG), and its life-history traits using an age-stage, two-sex life table, and its settling preferences on Dowling (resistant) and Heinong 51 (HN51, susceptible) soybean cultivars. The Dowling cultivar showed strong antibiosis against A. solani. Aphids feeding on Dowling exhibited significantly reduced survival, fecundity, and longevity, and increased nymph duration. Moreover, Dowling had negative impacts on the demographic parameters of the aphids. The number of A. solani individuals was significantly less on Dowling than on HN51, indicating the antixenotic effects of Dowling. As shown using EPG, the mechanical blocking wave (F) of A. solani was significantly longer after feeding on Dowling than after feeding on HN51, indicating that Dowling has a higher mechanical resistance. In conclusion, Dowling exhibited strong resistance to A. solani. These results are beneficial for integrated pest management in soybean fields and breeding programs.

Genome-Wide Comparative Analysis of the Cytochrome P450 Monooxygenase Family in 19 Aphid Species and Their Expression Analysis in 4 Cereal Crop Aphids

Cytochrome P450 monooxygenases (CYP450s) play a variety of physiological roles, including pesticide resistance, plant allelochemical detoxification, and hormone metabolism catalysis. However, limited information is available on the classification and expression profiles of the CYP450 gene family in aphid species. This is the first study to identify the cytochrome P450 gene family in 19 aphid species at the whole genome level. A total of 1100 CYP450 genes were identified in 19 aphid species. Three hundred CYP450 genes belonged to six cereal crop aphid species, which were further classified into four subfamilies according to the phylogenetic relationship. The conserved motifs, exon-intron structures, and genomic organization of the same subfamilies were similar. Predictions of subcellular localization revealed that the endoplasmic reticulum harbored the majority of CYP450 proteins. In Sitobion avenae and Rhopalosiphum maidis, the increase in the CYP450 gene was primarily caused by segmental duplication events. However, only tandem duplication occurred in the CYP450 gene family of Diuraphis noxia, Rhopalosiphum padi, Schizaphis graminum, and Sitobion miscanthi. Synteny analysis found three continuous colinear CYP450 gene pairs among six cereal crop aphid species. Furthermore, we obtained the expression profiles of four cereal crop aphids, including R. padi, D. noxia, S. graminum, and S. avenae. Differential expression analysis provided growth stage specificity genes, tissue specificity genes, organ specificity genes and some detoxification metabolic genes among these four cereal crop aphids. Meanwhile, their expression patterns were showed. The related functions and pathways of CYP450s were revealed by GO and KEGG enrichment analysis. Above all, we picked the differentially expressed CYP450 genes from all of the differentially expressed genes (DEGs). These differentially expressed CYP450 genes provided some new potential candidates for aphid control and management. This work establishes the foundation for further investigations into the regulatory functions of the CYP450 gene family in aphid species and beyond.

Cannabis sativa: A look at protozoa, helminths, insect vectors, and pests

Active principles extracted from plants, such as essential oils, have been commonly described in the literature as therapeutic targets for numerous pathological conditions. Cannabis sativa, which has an ancient and peculiar history, has been used for various purposes, from recreational to compounds of pharmacotherapeutic and industrial importance, such as pesticides based on this plant. It is a plant that contains approximately 500 described cannabinoid compounds and is the target of in vitro and in vivo studies at different locations. This review clarifies the role of cannabinoid compounds in parasitic infections caused by helminths and protozoa. In addition, this study briefly presented the use of C. sativa constituents in the formulation of pesticides for vector control, as the latter topic is justified by the economic burden faced by several regions where vector-borne diseases are a troubling reality. Studies involving cannabis compounds with pesticidal potential should be encouraged, especially those that evaluate their effectiveness against the different life cycles of insects, seeking to interrupt vector proliferation after egg laying. Actions aimed at the management and cultivation of plant species with ecologically correct pharmacotherapeutic and pesticide potentials are becoming urgent.

Adaptability of Two Soybean Aphid Species to High Diurnal Temperatures

The local temperature in the Harbin region of northeast China has been rising, with temperatures above 27°C often being recorded. The soybean aphid, Aphis glycines (Matsumura) (Hemiptera: Aphididae), and foxglove aphid, Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae), are important pests in soybeans in the region, which face great survival pressure due to rising temperatures. In this study, A. glycines and A. solani were reared at thermoperiods with diurnal temperatures of 25, 27, 29, 31, 33, 35, and 37°C, nocturnal temperature of 20 °C, 70% ± 5% relative humidity, and a photoperiod of 14:10 (L: D) hr. Diurnal thermoperiod 25°C was used as control. Some life characteristics of the aphids were assessed. The adaptation of A. solani to high diurnal temperatures was found to be worse than that of A. glycines. Aphis glycines could develop and reproduce successfully at diurnal temperatures of 27-35°C, whereas A. solani could only develop and reproduce at 27-29°C. At diurnal thermoperiods at 25°C, adult lifespan of A. solani was as long as that of A. glycines. When diurnal temperatures increased from 27 to 31°C, adult lifespan of A. solani were shorter than those of A. glycines. At diurnal thermoperiods at 25 and 27°C, the body sizes of A. solani adults were larger than those of A. glycines. At diurnal thermoperiods at 29 and 31°C, the body size of A. solani adults were as large as those of A. glycines. Our results provide important information on the survival, development, and reproduction of A. glycines and A. solani exposed to temperatures above 27°C, which is important for evaluating the adaptability of aphids to high temperatures and predicting their dynamics in soybeans in northeast China, where the local environmental temperature continues to rise.

Life Table Construction under Different Temperatures and Insecticide Susceptibility Analysis of Uroleucon formosanum (Hemiptera: Aphididae)

Simple Summary

Aphids are major crop pests worldwide, and in China, Uroleucon formosanum is a common aphid pest of lettuce. However, there is little basic and applied information on the control of this pest. To obtain the basic information of this pest, a life table of U. formosanum under different temperatures was constructed. Also, the susceptibility of U. formosanum to six common-used insecticides (chlorpyrifos, abamectin, beta-cypermethrin, imidacloprid, nitenpyram, and thiamethoxam) was evaluated. Results showed that U. formosanum was not suitable to a lower temperature (17 °C), and U. formosanum was relatively sensitive to all six test insecticides. These data may help us to develop integrated management strategies for better population control of U. formosanum.

Abstract

Uroleucon formosanum is an important aphid pest of lettuce, but basic information on its biology is scarce. In this study, effects of three constant temperatures (17, 21, and 25 °C, simulating the mean temperature range in greenhouses) on the development and fecundity of U. formosanum were analyzed by constructing a life table. U. formosanum could develop and reproduce under all three temperatures, but the survival rate, development, and fecundity of U. formosanum were affected by temperature. The intrinsic rate of increase was lowest at 17 °C (0.17) and it was significantly less than at 21 °C (0.20) and 25 °C (0.23). Furthermore, U. formosanum had the lowest finite rate of increase (1.19) and the largest mean generation time (20.21) at 17 °C. These results mean that U. formosanum is less adapted to the lower temperatures (17 °C) among these three set temperatures. To screen insecticides for control, susceptibility of U. formosanum to six insecticides including chlorpyrifos, abamectin, beta-cypermethrin, imidacloprid, nitenpyram, and thiamethoxam was evaluated. U. formosanum was relatively sensitive to all six test insecticides. Chlorpyrifos had the highest toxicity to U. formosanum (LC₅₀ = 3.08 mg/L). These data may help to develop integrated management strategies for better population control of U. formosanum.

Effects of Elevated CO2 on the Fitness of Three Successive Generations of Lipaphis erysimi

Simple Summary

Global warming caused by the increase in atmospheric CO₂ concentration is becoming a major environmental issue. Lipaphis erysimi is one of the most damaging pests of cruciferous crops worldwide, and L. erysimi has strong adaptability to the environment and reproductive capacity. The age-stage, two-sex life table is currently used by many researchers in place of the traditional age-specific life table, providing many details such as fitness and potential damage. In this study, the individual fitness and population dynamics parameters of three successive generations of L. erysimi were analyzed using the age-stage, two-sex life table. The results show that a high CO₂ concentration had a cumulative effect on the survival rate and fecundity of L. erysimi, and elevated CO₂ had a negative effect on the individual fitness parameters of L. erysimi. The life expectancy (e_xj) is significantly lower in elevated CO₂ than that in ambient CO₂ treatment in the three successive generations, indicating that L. erysimi was more sensitive to CO₂ concentration and the life of L. erysimi was shortened under elevated CO₂. Additionally, we can find that elevated CO₂ has a short-term effect on the population parameters, including the intrinsic rate of increase (r) and finite rate of increase (λ) in L. erysimi. Through the data from this experiment, we believe that the individual and population fitness of L. erysimi will be decreased under elevated CO₂, which indicates that the damage caused by L. erysimi may be reduced in the future with increasing CO₂ levels.

Abstract

To assess the effect of elevated CO₂ on the development, fecundity, and population dynamic parameters of L. erysimi, the age-stage, two-sex life table was used to predict the individual fitness and population parameters of three successive generations of L. erysimi in this study. The results show that a significantly longer total pre-adult stage before oviposition (TPOP) was observed in the third generation compared with the first generation of L. erysimi under the 800 μL/L CO₂ treatment. The fecundity is significantly lower in the 800 μL/L CO₂ treatment than that in the 400 μL/L CO₂ treatment in the third generation of L. erysimi, which indicates that elevated CO₂ had a negative effect on the individual fitness parameters of L. erysimi. Additionally, the life expectancy (e_xj) is significantly lower under the 800 μL/L CO₂ treatment than that under the 400 μL/L CO₂ treatment in the three successive generations. A significantly higher intrinsic rate of increase (r) and finite rate of increase (λ) were found in the second generation compared with those in the first and third generations of L. erysimi under the 800 μL/L CO₂ treatment. Moreover, significantly lower r and λ were observed under the 800 μL/L CO₂ treatment compared with those under the 400 μL/L and 600 μL/L CO₂ treatments in the first generation of L. erysimi, which indicates that elevated CO₂ has a short-term effect on the population parameters (r and λ) of L. erysimi. Our experiment can provide the data for the comprehensive prevention and control of L. erysimi in the future with increasing CO₂ levels.

Population Parameters and Growth of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) under Fluctuating Temperature

Simple Summary

The bean bug, Riptortus pedestris, is a polyphagous species that is an important pest of soybean fields in Asian countries. In this study, we examined the effects of constant and fluctuating temperatures on the development and reproduction of R. pedestris. The effects of thermal conditions were assessed by constructing age-stage, two-sex life tables from a constant temperature of 24 °C and simulated fluctuating temperatures of 24 ± 4 °C, 24 ± 6 °C, and 24 ± 8 °C. At a constant temperature, a number of R. pedestris life table parameters differed from those under fluctuating temperatures. Although similar pre-adult development periods were recorded under constant and fluctuating temperatures, the periods of female longevity and oviposition periods under fluctuating temperatures were significantly longer than those at a constant temperature. Given that temperature is an important abiotic factor for forecasting the population dynamics of arthropods in nature, determining the effects of fluctuating temperatures will make a valuable contribution to predicting R. pedestris population growth.

Abstract

In this study, we determined the influence of fluctuating temperatures on the development and fecundity of the bean bug Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) by collecting life table data for individuals exposed at a constant temperature (24 °C) and three fluctuating temperatures (24 ± 4 °C, 24 ± 6 °C, and 24 ± 8 °C). The raw life history data were analyzed using an age-stage, two-sex life table to take into account the viable development rate among individuals. Based on these analyses, the population projections enabled us to determine the stage structure and variability of population growth under different temperature treatments. Our results revealed shorter periods of immature development and a higher pre-adult survival rate at 24 ± 6 °C than under the other assessed temperature conditions. Furthermore, significant reductions in female longevity were recorded at 24 °C, whereas the fecundity, net reproductive rate, and intrinsic and finite rates of increase were highest at 24 ± 6 °C. These findings reveal that fluctuating temperatures have a positive influence on the life history traits of R. pedestris and indicate that observations made under constant temperatures may not explain sufficiently enough the temperature dependent biological performances of pests in the field.