Development of the omnivorous predator Dicyphus errans when fed on different prey regimes and its total prey consumption during the nymphal stage
Abstract: The native omnivorous predator Dicyphus errans (Wolff) (Heteroptera: Miridae) is usually reported in outdoor crops and in greenhouses in the Mediterranean basin and North-Central Europe. The effect of food availability rate on its nymphal development was investigated on tomato leaflets in Petri dishes in the following cases: a) when the predator had access to Ephestia kuehniella Zeller eggs (‘prey’) available ad libitum but only for 24 hours: 1) on the first day of the first instar, 2) on the first day of the second instar, 3) on the first day of the first and the third instar, and 4) when fed for 24 h at each nymphal instar (i.e. 5 meals in total). For comparison, development was recorded in the absence of prey and when prey was available continuously. The experiments were conducted at 25 ± 1 °C, 65 ± 5% RH, with a photoperiod of 16:8 (L:D) h. In the absence of prey, D. errans nymphs failed to molt to adults. When presented with a meal during the first instar a single adult (male) emerged after 21 days. When the meal was offered at the second instar adult emergence reached 20%, requiring 28.7 days on average. When two meals were offered, 60% of the nymphs reached adulthood, in 19.3 days; all nymphs reached adulthood in 19 days when fed at each instar. The total number of E. kuehniella eggs consumed by D. errans nymphs during their development was also determined. A total of 20, 40, 60, 80 and 110 E. kuehniella eggs were offered every single day to nymphs during their 1st, 2nd, 3rd, 4th and 5th instar, respectively. During their development D. errans female nymphs consumed 260.25 and male nymphs 208.57 eggs. On average, females took 17.3 days to reach adulthood and males took 16.7 days; 100% of the nymphs reached adulthood. The data collected may be useful in the development of mass rearing programs for D. errans and in its application in IPM strategies.