The effect of parasitism by Aphidius smithi (Hymenoptera: Aphidiidae) on the food budget of the pea aphid, Acyrthosiphon pisum (Homoptera: Aphididae)

1979 ◽  
Vol 57 (8) ◽  
pp. 1605-1611 ◽  
Author(s):  
Conrad Cloutier ◽  
Manfred Mackauer

Parasitism by Aphidius smithi affected the food budget of its host, Acyrthosiphon pisum, fed on a synthetic diet. During the embryonic stage of the parasite, the weight-specific rates of feeding, food assimilation, and growth were less in parasitized aphids than in controls. In the presence of a developing parasite larva, aphids ingested more food but assimilated it less efficiently; they achieved the same or a higher relative growth rate than nonparasitized aphids as a result of having either a higher feeding rate or a higher efficiency of incorporation of assimilated food, or both. Honeydew excretion was up to 129% higher in aphids containing a parasite larva. Parasitism by A. smithi did not obviate host feeding and capacity for growth until host size was sufficient for the successful development of the parasite larva.It is suggested that the nutritional requirements of the parasite larva differ from those of the aphid. Thus parasitism affects the homeostatic regulation of aphid feeding and food assimilation by causing an imbalance of nutrients in the host's haemolymph.

1980 ◽  
Vol 58 (2) ◽  
pp. 241-244 ◽  
Author(s):  
Conrad Cloutier ◽  
Manfred Mackauer

The food budget of diet-fed, second-instar pea aphids when superparasitized by Aphidius smithi was similar to that of single-parasitized aphids. Aphids containing two parasite eggs or embryos consumed less diet and grew at a slower rate than did healthy controls. Feeding, assimilation, and growth increased significantly after the parasite larva(e) had hatched from the trophamnion. During the late stages of parasite larval development, host growth was increased by 133% and honeydew excretion by 146% over control values. During the same period, parasitized aphids converted ingested and digested food, respectively, with 66% and 86% greater efficiency than did controls. These increases were higher than in single-parasitized aphids, perhaps as a result of the larger number of teratocytes present in superparasitized hosts.


1990 ◽  
Vol 122 (3) ◽  
pp. 503-513 ◽  
Author(s):  
J.J. Soroka ◽  
P.A. Mackay

AbstractPopulations of pea aphid, Acyrthosiphon pisum (Harris), were sampled through the summer of 1984 on five cultivars and in 1985 and 1986 on six cultivars of field peas, Pisum sativum L., grown in field plots in southern Manitoba. Patterns of pea aphid population growth were generally similar among cultivars in any one year. Aphid populations on all cultivars in all years remained relatively low until mid-July, then increased rapidly, peaked at about the beginning of August, and declined sharply to low levels in late August. At the time of peak aphid numbers, significant differences in aphid population densities were found among cultivars in 2 years; the lowest densities were found on the cultivars Century and Tipu, and the highest densities on Triumph or Trapper. Pea aphid feeding was not detrimental to any yield parameters except 1000 seed weight. In 1984 Triumph and Tara, and in 1985 Triumph had significantly decreased 1000 seed weights in plots in which aphid densities were not controlled. Differences in the abundance of the aphid among cultivars were not reflected in their yield responses. Over 3 years the regression line of aphid densities upon Century seed weight was significantly steeper than those of Trapper, Lenca, or Tara. Trapper was least affected by aphid feeding. Results indicated that the economic threshold of pea aphids on peas other than Century needs to be re-evaluated.


EUGENIA ◽  
2006 ◽  
Vol 12 (4) ◽  
Author(s):  
Sonny H. Marthen ◽  
Cyska Lumenta

This research was carried out at spp (Sekolah Pertanian Pembangunan) Manado Kalasey. The fishwere reared in karamba (9 units) each units contained 50 fish, 14-16 weight. The experiment will be tested using completely random design using 3 deffierent treatment. One treatment is using comercial pellet and two treatmens all using pellets added with and swampcabbage stalk flour 20% and 30 %, each treatment hare 3 replicateries. Feeding frecuenci was 3 times a day and feeding rate was 5 % of their body weight the growth was observed every two weeks. The result analysis from 3 treatment show that the relative growth of treatment A was (312.67%) B was (282.79%), and C (262.41%). The was effisincy feeding foor treatment A was hare (49.43%), B was 48.78% and C was 47.26  5% Where as nutient conversion rate A was are (0%), B was 3.47% and C was (3.82%).Keywords: Swamp cabbage stalk flow (Ipomea aquatica) Nila gif, karamba


1987 ◽  
Vol 65 (4) ◽  
pp. 666-672 ◽  
Author(s):  
C. D. B. Hawkins ◽  
M. I. Whitecross ◽  
M. J. Aston

The short-term effects of the feeding of cowpea aphids (Aphis craccivora Koch) and pea aphids (Acyrthosiphon pisum (Harris)), both Homoptera: Aphididae, on 14C translocation and plant growth of broadbean (Vicia faba L. cv. Aquadulce), cowpea (Vigna unguiculata (L.) Walp. cv. Caloona), and garden pea (Pisum sativum L. cv. Victory Freezer) seedlings were investigated, but not all plant–aphid combinations were utilized. Within 10 days of infestation, aphid feeding reduced the flux of translocate to the roots, changed the assimilate partitioning pattern in affected shoots, and apparently induced assimilate sources to become assimilate sinks. Cowpea aphid feeding also caused more lateral branches to be formed in broadbean. Some of these effects may be related to the imbibing of translocate by aphids, while other effects may result from a series of interactions involving substances in the saliva of aphids, plant hormones, and the assimilate ratio of sources–sinks. The amount of radioactivity found per unit weight of aphid tissue increased between days 5 and 10 in all four plant–aphid combinations. This may indicate that the nymphs were incapable of feeding on the larger phloem elements. Except for the decreased rate of translocation to the roots, the effect of aphid feeding on translocation is plant–aphid species specific.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1863 ◽  
Author(s):  
Xin Liu ◽  
Youjun Zhang ◽  
Wen Xie ◽  
Qingjun Wu ◽  
Shaoli Wang

Encarsia formosaGahan (Hymenoptera: Aphelinidae) is a solitary endoparasitoid that is commercially reared and released for augmentative biological control of whiteflies infesting greenhouse crops. In most areas in China, the invasive and destructive whiteflyBemisia tabaci(Gennadius) (Hemiptera: Aleyrodidae) biotype Q has replacedB. tabacibiotype B and has become dominant between the two. A better understanding of the suitability of different nymphal instars ofB. tabacibiotypes Q and B as hosts forE. formosais needed to improve the use of this parasitoid for biological control. Parasitism of the four nymphal instars ofB. tabacibiotypes Q and B by the commercial strain ofE. formosamass reared onTrialeurodes vaporariorum(Westwood) (Hemiptera: Aleyrodidae) was assessed in the laboratory. The results indicated thatE. formosaparasitized and successfully developed on all instars of both biotypes but performed best on the 3rd instar ofB. tabacibiotype B and on the 2nd, 3rd, and 4th instars ofB. tabacibiotype Q. The host-feeding rate of the adult parasitoid was generally higher on nymphal instars ofB. tabacibiotype Q than on the corresponding nymphal instars of biotype B and was significantly higher on the 2nd and 3rd instars. For both whitefly biotypes, the parasitoid’s immature developmental period was the longest on the 1st instar, intermediate on the 2nd and 3rd instars, and the shortest on the 4th instar. The parasitoid emergence rate was significantly lower on the 1st instar than on the other three instars and did not significantly differ betweenB. tabacibiotype B and biotype Q. Offspring longevity was greater on the 3rd and 4th instars than on the 1st instar and did not significantly differ between the twoB. tabacibiotypes. The results indicate that commercially-producedE. formosacan parasitize all instars ofB. tabacibiotypes B and Q, making this parasitoid a promising tool for the management of the two biotypes ofB. tabacipresent in China.


Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 407
Author(s):  
Arinder K. Arora ◽  
Seung Ho Chung ◽  
Angela E. Douglas

Insect pest control by RNA interference (RNAi)-mediated gene expression knockdown can be undermined by many factors, including small sequence differences between double-stranded RNA (dsRNA) and the target gene. It can also be compromised by effects that are independent of the dsRNA sequence on non-target organisms (known as sequence-non-specific effects). This study investigated the species-specificity of RNAi in plant sap-feeding hemipteran pests. We first demonstrated sequence-non-specific suppression of aphid feeding by dsRNA at dietary concentrations ≥0.5 µg µL−1. Then we quantified the expression of NUC (nuclease) genes in insects administered homologous dsRNA (with perfect sequence identity to the target species) or heterologous dsRNA (generated against a related gene of non-identical sequence in a different insect species). For the aphids Acyrthosiphon pisum and Myzus persicae, significantly reduced NUC expression was obtained with the homologous but not heterologous dsRNA at 0.2 µg µL−1, despite high dsNUC sequence identity. Follow-up experiments demonstrated significantly reduced expression of NUC genes in the whitefly Bemisia tabaci and mealybug Planococcus maritimus administered homologous dsNUCs, but not heterologous aphid dsNUCs. Our demonstration of inefficient expression knockdown by heterologous dsRNA in these insects suggests that maximal dsRNA sequence identity is required for RNAi targeting of related pest species, and that heterologous dsRNAs at appropriate concentrations may not be a major risk to non-target sap-feeding hemipterans.


1996 ◽  
Vol 199 (6) ◽  
pp. 1269-1276 ◽  
Author(s):  
J Rhodes ◽  
P Croghan ◽  
A Dixon

Ingestion, excretion and respiration in aphids were studied using artificial diets labelled with radioactive sucrose or amino acids. The rate of ingestion of a 25 % w/v sucrose diet was 12.4 nl mg-1 h-1 and the honeydew excretion rate was 5.3 nl mg-1 h-1, about 43 % of the volume ingested during the same period. The concentration of sugars in the honeydew was equivalent to 0.53 mol l-1 sucrose and 69 % of the sucrose ingested was assimilated. The amino acid concentration of honeydew was 24.6 mmol l-1 and 94 % of the ingested amino acids were assimilated. Respiration was measured by collecting respired 14CO2 using a chamber which allowed the aphids to feed during the experiments on 14C-labelled artificial diets. While feeding on a 25 % w/v sucrose diet, sucrose was respired at the rate of 1.32x10(-6) mmol mg-1 h-1, equivalent to 0.354 µl O2 mg-1 h-1, which was 14.6 % of the rate of ingestion. There was no evidence that reducing the dietary sucrose concentration from 22 to 11 % w/v had any effect on the rate at which sucrose was respired. Amino acids were respired at a rate of 0.14x10(-6) mmol mg-1 h-1, which was 6.4 % of the rate of ingestion. Dietary sucrose was oxidised in preference to amino acids.


2020 ◽  
Vol 113 (3) ◽  
pp. 1211-1220 ◽  
Author(s):  
Yu-Jie Jia ◽  
Bo Wang ◽  
Tong-Xian Liu

Abstract The biocontrol values of natural enemies are strongly correlated to their ability to regulate the density of their host/prey. For parasitoids, apart from parasitism and host feeding, unsuccessful host stinging (i.e., stings that were aborted, abandoned, or discontinued without oviposition or host feeding) can also negatively affect their hosts and host populations. Although several studies have reported unsuccessful host stinging and its impacts on hosts, the effects of this type of attack on host life table parameters are still unclear. In the present study, we used the parasitoid Aphelinus asychis Walker (Hymenoptera: Aphelinidae) and its host Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae) to investigate the influence of unsuccessful host stinging on host populations under laboratory conditions at. Biological parameters of A. pisum were analyzed using an age stage, two-sex life table. The results of this study showed that unsuccessful host stinging was prevalent under laboratory conditions, and the frequency of this type of attack on third- and fourth-instar hosts was higher than the frequencies of parasitism and host feeding. Unsuccessful host stinging adversely impacted aphid populations, by decreasing aphid survival and reproduction, and impacts were greatest in hosts attacked at the first and fourth instars. These results indicate that unsuccessful host stinging enhances the biological control impact of A. asychis attacking A. pisum, and its effect on host populations should also be considered when selecting and mass rearing of parasitoids for biological control.


1985 ◽  
Vol 63 (12) ◽  
pp. 2454-2459 ◽  
Author(s):  
C. D. B. Hawkins ◽  
M. J. Aston ◽  
M. I. Whitecross

The effects of various densities of cowpea aphids (Aphis craccivora Koch) and pea aphids (Acyrthosiphon pisum Harris), both Homoptera: Aphididae, on the growth of cowpea (Vigna unguiculata (L.) Walp. cv. Caloona), broad bean (Vicia faba L. cv. Aquadulce), and garden pea (Pisum sativum L. cv. Victory Freezer) seedlings were investigated. Within 10 days of infestation, aphid feeding significantly reduced plant dry weights and mean relative growth rates for the six plant–aphid combinations. In all cases except one, the mean unit leaf or net assimilation rate was also significantly reduced within 10 days. The mean leaf area ratio was the same for infested and control plants. The aphid-induced changes in host plants appear to be due to changes in photosynthesis, respiration, and translocate removal from the phloem over the 10-day period. Changes in the growth patterns of the host plant within this period are similar, but the underlying physiological effects could vary among particular plant–aphid combinations.


Biologia ◽  
2009 ◽  
Vol 64 (2) ◽  
Author(s):  
Sylwia Goławska ◽  
Iwona Łukasik

AbstractThis research aims to examine the effect of phenolics on pea aphid (Acyrthosiphon pisum) (Homoptera: Aphididae) development and feeding behaviour, on leaves of selected low-saponin lines of Radius alfalfa (Medicago sativa). There was a slight, negative correlation (Spearman rank correlation r s = −0.80) between concentrations of saponins and phenols. Lines with higher concentrations of saponins had less phenolics. Levels of phenolics in low-saponin lines of alfalfa cv. Radius were related to their acceptance by the pea aphid. Our data revealed an inverse relationship between level of phenolics and the aphid abundance and its biology on studied alfalfa lines. Larval development of the pea aphid was longer, reproduction period was shorter, and the fecundity was lower on low-saponin lines with higher level of phenolics. There were observed some tendencies in the pea aphid feeding behaviour on these lines: prolonging the probing of the peripheral tissues (epidermis and mesophyll) and shortening the period of phloem sap ingestion. The better hosts for the pea aphid were low-saponin lines with low levels of phenolic compounds.


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