Longevity, fecundity and embryogenesis in Brazilian aphids

Abstract

Aphids cause great damage to cultivated crops. With the aim of aid managing methods, biological properties subject to heavy selection were studied in the three south Brazilian species Schizaphis graminum, Sitobion avenae and Rhopalosiphum padi (Homoptera: Aphididae). Changes in embryonic outer morphology were analysed under contrast phase microscope and eight stages were described. The embryonic period terminated after 20, 24 and 26 hours; the longevity (expressed in number of days from nymph to adult death) was of 31.13 ± 2.79, 29.73 ± 1.5, 25.13 ± 3.22 and the fecundity (number of nymphs per adult aphid) was of 66.87 ± 8.05, 31.67 ± 3.75, 49.53 ± 6.26, respectively. When the fecundity/longevity ratio was compared it was concluded that S. graminum was the most dangerous to wheat, and BR-35 wheat strain was the most susceptible to aphid control. The differences in embryonic time and morphological characteristics can be used to classify the three species.