Influence of host plant on susceptibility of the aphid Acyrthosiphon pisum (Hemiptera: Aphididae) to the fungal pathogen Pandora neoaphidis (Zygomycetes: Entomophthorales) (original) (raw)
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Effects of Host Plants on the Growth, Reproduction, and Defense in Pea Aphids, Acyrthosiphon Pisum
Background: Pea aphids (Acyrthosiphon pisum) possess a weak immune system, but they can firmly mount immunological responses. However, the influence of different plants on their defense against different microbes remains largely unknown. In addition, no previous research has integrated the growth, reproduction, and defense responses of pea aphids feeding on different plants. Objective: This study aims to investigate the growth, reproduction, and defense responses of pea aphids feeding on different plants. Methods: Pea aphids were cultivated on both Medicago sativa and Vicia faba. Growth and reproduction were evaluated. Additionally, we monitored the survival and microbial loads of pea aphids after bacterial and fungal infections. Results: Pea aphids reared on M. sativa had lower growth, lower intrinsic rate of increase, and lower finite rate of increase when compared to aphids feeding on V. faba. The net reproduction was lower in aphids feeding on M. sativa, although the difference was not significant. The mean time of generation and pre-reproductive periods was longer for aphids reared on M. sativa than for aphids reared on V. faba. In the infection experiments, we found that aphid survival was not affected by the host plant. However, aphids reared on M. sativa generally harbored fewer microbial loads than those reared on V. faba. Conclusions: The growth and reproduction of pea aphids are affected by the host plant. Aphids feeding on different plants had different tolerances to microbial infections. Our study sheds light on improving biological control program for aphids.
Biocontrol Science and Technology, 2012
The cotton aphid is one of the most serious pests of greenhouse vegetable crops worldwide. It is difficult to control because field populations usually include simultaneously several insect developmental stages. The current research evaluated an isolate (CS625) of Lecanicillium attenuatum, a fungal pathogen of aphids, as to its virulence against different developmental stages of cotton aphid, Aphis gossypii. The influence on mortality of several other factors also was examined: (a) insect moulting, (b) the number of conidia attached to insect cuticles and (c) germination rates of conidia on cuticles of aphids at various developmental stages. Mortality of cotton aphids treated with L. attenuatum conidia varied according to the developmental stage of the host, i.e. the LT 50s with third-instar nymphs and adults was shorter than with first-instar nymphs. The number of spores attached to the surface of first-instar nymphs was approximately one-half of that on third-instar nymphs and adults. Also, the level of spore germination on the surface of first-instar nymphs was lower than on the surface of other stages of the aphid. After moulting, the numbers of conidia attached to new insect cuticles were less than on exuviae. These results suggest that early nymphal stages of cotton aphids may escape fungal disease due, at least in part, to a combination of three factors: low numbers of conidia attached to their cuticles; low levels of conidial germination and rapid ecdyses, which removed conidia before their germ tubes penetrated the host hemolymph.
Entomopathogenic Fungi on Fabae bean Aphid, Aphis craccivora (Koch) (Hemiptera: Aphididae)
Romanian Biotechnological Letters
The Aphids, Aphis craccivora (Koch) is a serious pest in agricultural fields in Egypt. Entomopathogenic fungi are biological control agents of insects. The study was carried out on the aphid by using of Bio Catch, Verticillium lecanii, Bio Power, Beauveria bassiana and Bio Magic, Metarhizium anisopliae on A. craccivora. Laboratory experiments were done to measure the pathogenicity of three commercial compounds from entomopathogenic fungi, Bio Catch, V. lecanii, Bio Power, B. bassiana, and Bio Magic, M. anisopliae against adults and nymphs of A. craccivora. Three concentrations were used from all compounds, 107 , 108 and 109 spores/ml. at 22 ± 2°C and 75 ± 5 R.H. The concentration (109 spores/ml.) gave 100% mortality with V. lecanii and B. bassiana then M. anisopliae. The Lowest LC50 value of 2.1 x 106 spores/ml. was recorded by V. lecanii, which showed higher virulence compared to other entomopathogenic fungi. The LC50 values of V. lecanii, B. bassiana and M. anisopliae were 2.1 x 1...
Applied Entomology and Zoology, 2014
Aphids (Homoptera: Aphididae) are sap-sucking insect pests that feed on several plants of agronomical importance. Entomopathogenic fungi are valuable tools for potential aphid control. As part of a selection process, laboratory bioassays were carried with five different concentrations of Aspergillus clavatus (Desmazières), Aspergillus flavus (Link) and Metarhizium anisopliae ((Metschnikoff) Sorokin) spores against the pea aphid, Acyrthosiphon pisum (Harris). Aspergillus isolates induced higher mortalities than M. anisopliae, which is a wellknown entomopathogen in the literature. Lethal concentrations (LC 50 and LC 90 ) were 1.23 9 10 3 and 1.34 9 10 7 spores/ml for A. flavus, 4.95 9 10 2 and 5.65 9 10 7 spores/ml for A. clavatus, and 3.67 9 10 3 and 9.71 9 10 7 spores/ml for M. anisopliae 5 days after treatment. Mycelia development and sporulation on adult cadavers were observed 48 h after incubation. The intrinsic growth rate of A. pisum decreased with increased spore concentration for all fungal strains, suggesting an increase in pathogen fitness related to a consumption of host resources. In conclusion, Aspergillus species could be useful in aphid control as pest control agents despite their saprophytic lifestyle. This is also to our knowledge the first report of A. clavatus and A. flavus strains pathogenic to aphids.
Fight or Flight? Alternative Defense of the Pea Aphids, Acyrthosiphon pisum on Different Host Plants
Insects
Non-immunological responses are important alternative strategies for animals to deal with pathogens. It has long been recognized that fecundity compensation and production of winged offspring are two common non-immunological responses used by aphids when confronted with predators or pathogens. However, the effects of host plant on these responses have received little attention. This study investigated the effects of host plant on non-immunological defense in the pea aphids, Acyrthosiphon pisum, after bacterial and fungal infections. The aphids were raised in two groups, with one group being raised on broad beans and the other group being raised on alfalfa. The secondary symbiont background was examined, and the aphids were then infected with bacteria and fungus to assess fecundity and winged offspring production. We found that aphids that had been fed alfalfa had fewer offspring than those fed broad beans. Alfalfa-fed aphids produced more winged offspring in response to S. aureus an...
Entomologia Experimentalis Et Applicata, 2010
In order to reduce parasite-induced mortality, hosts may be involved in mutualistic interactions in which the partner contributes to resistance against the parasite. The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbours secondary bacterial endosymbionts, some of which have been reported to confer resistance against aphid parasitoids. Although this resistance often results in death of the developing parasitoid larvae, some parasitoid individuals succeed in developing into adults. Whether these individuals suffer from fitness reduction compared to parasitoids developing in pea aphid clones without symbionts has not been tested so far. Using 30 pea aphid clones that differed in their endosymbiont complement, we studied the effects of these endosymbionts on aphid resistance against the parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae: Aphidiinae), host-parasitoid physiological interactions, and fitness of emerging adult parasitoids. The number of symbiont species in an aphid clone was positively correlated with a number of resistance measurements but there were also clear symbiont-specific effects on the host-parasitoid interaction. As in previous studies, pea aphid clones infected with Hamiltonella defensa Moran et al. showed resistance against the parasitoid. In addition, pea aphid clones infected with Regiella insecticola Moran et al. and co-infections of H. defensa-Spiroplasma, R. insecticola-Spiroplasma, and R. insecticola-H. defensa showed reduced levels of parasitism and mummification. Parasitoids emerging from symbiontinfected aphid clones often had a longer developmental time and reduced mass. The number of teratocytes was generally lower when parasitoids oviposited in aphid clones with a symbiont complement. Interestingly, unparasitized aphids infected with Serratia symbiotica Moran et al. and R. insecticola had a higher fecundity than unparasitized aphids of uninfected pea aphid clones. We conclude that in addition to conferring resistance, pea aphid symbionts also negatively affect parasitoids that successfully hatch from aphid mummies. Because of the link between aphid resistance and the number of teratocytes, the mechanism underlying resistance by symbiont infection may involve interference with teratocyte development.
2021
Given the aphids high reproductive capacity, assessing their biocontrol by using entomopathogenic fungi is crucial; to determine their potential, fungi were tested in planta and in field conditions. Significant decrease of Myzus persicae (Sulzer) population was observed in planta after applying Beauveria bassiana (strain 7R), Trichoderma gamsii (strain Z) or Metarhizium brunneum (strain Meta Br1) at 1 × 107 or 1 × 108 conidia/mL on pepper plants. Significant differences of aphids’ populations were detected between fungus concentration and control (F = 68.743, df = 6.980, P <0.001), where M. brunneum at 1 × 108 conidia/mL reduced aphids population close to zero. At 20 °C, dead aphids’ mycosis by B. bassiana and T. gamsii was 78% and 84%; at 25 °C was 83% and 88%; and at 30 °C was 75% and 79%, respectively. Mexican PTG4 and commercial GHA B. bassiana strains were tested in field (treating seeds with 1 × 106 conidia/mL) against the Melanaphis sacchari (Zehntner) aphid populations, o...
Biology of the Pea Aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae) on Cool-Season Legumes
International Journal of Tropical Insect Science, 2000
The biology of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), on four legumes (faba bean, field pea, lentil and grass pea) was studied in a greenhouse during the 1999/2000 seasons. There was no significant difference in length of nymphal period and number of moults (instars) among the crop species tested. The aphids generally took 9 to 11 days to reach the adult stage with a maximum of 3 moults. Lifespan was significantly longer on lentils than on other crops. Significantly more aphids survived beyond 15 days on lentil than on other crops. Similarly, the reproductive and post-reproductive period and adult longevity were longer on lentil. The prereproductive period was significantly higher on field pea than on the other crops. The net reproductive rate (RJ was highest on lentil (103.56 females/female) and the intrinsic rate of increase (r) was highest on faba bean due to a short generation time (14.27 days). Generally, lifetime fecundity was higher on lentil (115.10/female) due to a higher daily reproduction raje (6.7 nymphs/female/day) on this crop. Nymphal production per aphid was strongly and positively correlated with lifespan, reproductive period and adult longevity but not of the nymphal period. Daily nymph production was significantly correlated with minimum temperature on lentil alone (F = 4.61, P < 0.05). Knowledge of the crop species and varieties susceptible to pea aphid is useful for identifying diets for the mass rearing of aphids for use in resistant variety selection and as diet for artificial natural enemy production. The present experiment indicates that lentil is suitable for both purposes.