Comparative Functional and Numeric Response of Two Coccinellids (Coccinella septempunctata and Cheilomenes sexmaculata) Preying Cowpea Aphid (Aphis craccivora)

2021 ◽  
Author(s):  
Gaurang Chhangani ◽  
M.K. Mahla ◽  
R. Swaminathan ◽  
Lekha . ◽  
H. Swami ◽  
...  
Keyword(s):  
Coccinella Septempunctata ◽  
Egg Laying ◽  
Aphis Craccivora ◽  
Prey Consumption ◽  
Linear Regression Method ◽  
College Of Agriculture ◽  
Cowpea Aphid ◽  
Aphis Craccivora Koch ◽  
Numeric Response

Background: The cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae), a plant lice known to commonly attack plants that causes loss by sucking sap from phloem and act as vector for viruses. The aphidophagous coccinellids are efficient in controlling the pestiferous population of aphids. The two coccinellid Coccinella septempunctata and Cheilomenes sexmaculata are efficient in predation of cowpea aphid, Aphis craccivora in southern Rajasthan. The present study determined the response of prey consumption at different prey densities. Methods: To compute the functional and numeric response of the lady bird beetle on cowpea aphid, experiment was conducted in vitro by using cowpea potted plant in caged conditions at Department of Entomology, Rajasthan College of Agriculture during 2019-20. The cowpea pea plants were sown in small pots and were placed in aluminium insect cages having 15 cm × 15 cm × 15 cm size. The predatory potential of coccinellid grubs and adults were evaluated at six different prey densities (aphids per arena): 25, 50, 75, 100, 125, 150 and 200 with 5 replications. Result: The grub and adults of C. septempunctata consumed more prey as compared to C. sexmaculata. Both the coccinellid showed Type II functional response when functional curve was plotted. The linear regression method suggested that C. septempunctata required less time to act upon prey as compared to C. sexmaculata. The C. septempunctata also showed more numeric response in terms of ECI [conversion efficiency of prey consumption (ECI) into biomass (egg)] at different prey densities. The fecundity in both the cases increased with the increased prey densities that eventually decreased after reaching the maximum egg laying capacity at prey density of 125 aphids. In all the cases it was found that consumption rate of predaceous beetle increased with increasing aphid population.

scholarly journals IN VITRO SCREENING OF INSECTICIDAL EFFECT OF PLANT AQUEOUS EXTRACTS ON THE COWPEA APHID APHIS CRACCIVORA

AGROFOR ◽  
2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Salim LEBBAL ◽  
Aissa LEBBAL ◽  
Azzeddine ZERAIB
Keyword(s):  
Chemical Control ◽  
Aphis Craccivora ◽  
Aqueous Extracts ◽  
Control Methods ◽  
Phytochemical Screening ◽  
Juniperus Thurifera ◽  
Negative Effects ◽  
Insecticidal Effect ◽  
Cowpea Aphid

The research of new control methods that have low negative effects represent analternative aiming to limit disadvantages of chemical control of pests. This studyaimed to test the effect of 11 aqueous plant extracts belonging to four species(Santolina africana, Juniperus thurifera, Artemisia herba-alba and Pituranthosscoparius), on the larvae of the aphid Aphis craccivora installed on the leaves ofRobinia pseudoacacia under laboratory conditions. The insecticidal effect ofaqueous extracts on the mortality of aphids was evaluated by the introduction ofacacia leaflet into an extract and infestation of them by 10 larvae of the aphid.Later, a counting of dead larvae after 3, 6, 12 and 24 h was performed. In addition,we investigated the effect of the aqueous extracts on the orientation of the aphidsby putting the latter in a position of choice between six leaflets, each treated with adifferent extract. In addition, a phytochemical screening was carried out to detectthe presence of saponins and polyphenols in the extracts studied. Through ourstudy, the extract obtained from S. africana at a concentration of 15% was the mosteffective with a mortality rate higher than 80% after 24 h of artificial infestation.As for the effect of the four extracts on the orientation of the cowpea aphid, theydid not attract the larvae massively. Regarding phytochemical screening,differences in the chemical composition of the analyzed extracts were observed.These differences may explain in part the variation of aphicidal effects of testedplant extracts.

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