Biology, predatory potential and functional response of Mallada desjardinsi (Navas) on melon aphid, Aphis gossypii glover

Abstract

This study evaluated the developmental biology, predatory potential, and functional response of Mallada desjardinsi (Neuroptera:Chrysopidae) larval instars fed on melon aphid, Aphis gossypii Glover. The experiment was carried out under laboratory conditions at 25 ± 1 °C, with 70 ± 5% R.H and 12:12 L:D photoperiod. The freshly emerged larvae were reared individually in the Petri plates containing moist blotting paper and cucumber leaves (6 × 6 cm) infested with assorted population of second and third instars of A. gossypii. The results showed that incubation, total larval, pre pupal and pupal periods of M. desjardinsi were 2.90, 12.50, 1.40 and 9.10 days, respectively. Pre oviposition, oviposition and post oviposition period of M. desjardinsi was 11.80, 32.40 and 2.76 days, respectively and each female laid an average of 128.58 eggs. The 1st, 2nd and 3rd instars of M. desjardinsi on an average consumed 30.98, 107.80 and 265.40 aphids, whereas total consumption during life cycle was 298.50 aphids/predator. All the three larval stages of the predator exhibited Type II functional response to the aphid. Based on Rogers’s random predator equation, the predator’s attack rate was the lowest (0.092) in the first instar, while the 3rd instar recorded the highest rate (0.118). Functional response parameters indicate that attack rate increased and handling time decreased with the advancement of the predator stage. From biological control point of view, our data suggest the successful use of M. desjardinsi third instar larvae as voracious feeders in IPM programmes against melon aphid.