Functional Response of Six - Spotted Zigzag Ladybird, Menochilus sexmaculatus (Fabricius) (Col.: Coccinellidae) to Pomegranate Green Aphid, Aphis punicae Pass. (Hem.: Aphididae) at Different Temperatures

Abstract

Introduction: Aphids are tiny soft-body insect pests which damage the host plant directly through sap feeding and indirectly by transmission of plant viruses. Pomegranate green aphid, Aphis punicae is a common pest of pomegranate gardens in Iran. In some years, the aphid dramatically damages under the suitable conditions in that they can grow and reproduce. Lady beetles are small, brightly colored insects and belong to family Coccinellidae. These predators obtain necessary resources for their survival and reproduction from a variety of habitats. Menochilussexmaculatus (Col.: Coccinellidae) is one of the major predators of pests reported in the gardens of Iran. The zigzag beetle is a general entomophagouscoccinellid that feeds upon soft body insects such as aphids. The adults of M sexmaculatus are bright yellow in color with black vertical zigzag lines. The adults and larva prey upon all stages of aphids. The study of the predation efficiency of M. sexmaculatus would increase its chances to be used as a biological control agent M. sexmaculatus is an efficient predator of many aphid species, e.g. the mustard aphid, LipaphiserysimiKalt. The zigzag, beetle widely distributed and feed on aphid species in India, Pakistan, Borneo, Jawa Indonesia, and the UK. The Philippines, Islands of Bali, France, Sumatra and South Africa. In this paper, we evaluated the effect of temperature on some biological parameters of M. sexmaculatus by feeding on pomegranate green aphid, A.punicae. Menochilussexmaculatus is an effective predator to be used as a bio-control agent but the major challenge is its mass rearing and augmentation Materials and Methods: The colony of M. sexmaculatus was established from about 100 adult beetles collected from a pomegranate orchard (GPS coordinates 30°23'42.31'' N and 55°56’51.11’ E) at Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran, in October 2013.. Adults were held In a ventilated plastic box (25.0 x 20.0 x 10.0cm) and fed by pomegranate green aphids in a climate-controlled growth chamber set to 25 ± 2 °C, 65 ± 5% RH and 16L: 8D photoperiod. The functional response of different stages of M.sexmaculatus to different densities of 3rd and 4th nymphal stages of pomegranate green aphid were studied at temperatures of 20, 22.5, 25, 27.5 and 30 (±1)°C, for adult females (10-days old) in temperatures of 25 and 27.5(±1)°C for 3rd and 4th larval stages, at 65 ± 5 RH and 16:8 L: D photoperiod. The densities of 2, 4, 8, 16, 32, 64, 100, and 128 3rd and 4th nymphal stages of aphid for 3rd and 4th larval stages and densities 8, 16, 32, 64, 100 and 128 for female and male adults. Females of lady beetle were used and the average feeding at any density was recorded after 24h. Type of functional response was determined using logistic regression and the searching efficiency (a) and handling time (Th), were estimated by nonlinear regression. All the data in the Excel 2007 program was set. Curves and graphs were plotted using Excel 2007 software. Results and Discussion: Type of the functional response of the all predator stages across all temperatures was type II. The results showed that the temperature is effective on functional response of predator, and searching efficiency of predator increased at temperatures of 22.5°C to 27.5°C. The maximum and minimum value of the searching efficiency were0.14 h-1 at 27.5°C and 0.0582 h-1 at 22.5°C and of handling time were 0.26 h at 20°C and 0.0182h at 22.5°C for adult females respectively. Conclusion In general, the lady beetle at temperature of 27.5°C and in stages of 4th larval and adult would have the highest predatory efficiency. Application of this predator was interested in biological control programs of pomegranate green aphid. The data indicated that the M. sexmaculatus may be a useful candidate for the biological control of A. punacaein pomegranate gardens.