Biology and predation of the Chrysoperla carnea (Stephens) (Insecta: Neuroptera: Chrysopidae) feeding on two important spider mite pests (Acari: Tetranychidae) under low humidity.

The biology and predation of the generalist predator, Chrysoperla carnea (Stephen) (Neuroptera: Chrysopidae) were studied while feeding on motiles of two economically important spider mite pests: citrus brown mite (CBM), Eutetranychus orientalis (Klein) (Acari: Tetranychidae) and date palm mite (DPM), Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae) under low relative humidity (RH) (35 ± 5%). Results showed that the predator larvae did not pupate when fed on CBM and DPM motiles at both low and high RH. The shortest total predator larval duration was against motiles (14.65 ± 0.15 days) and eggs (15.42 ± 0.80 days) of CBM at low and high RH, respectively. Adult longevity, however, was higher when C. carnea was fed on the eggs of Ephestia cautella (Walker) (Lepidoptera: Pyralidae) (male: 32.00 ± 1.61 days; female: 36.75 ± 0.25 days) than CBM eggs (male: 13.00 ± 0.00; female: 31.00 ± 2.00). The highest total predation by the predator larvae were found against the eggs of CBM (12671.11 at high RH) followed by motiles of CBM and DPM (4696.53 and 4088.16 at low RH), respectively. Considering the significance of CBM and DPM as a pest in the arid climate of Saudi Arabia, it is essential to understand how C. carnea responds to these pests at low RH. These results depict that the predator larvae voraciously fed on eggs and motiles of mite pest species revealing its potential use as a biological control agent against spider mites at both low and high RH levels. The high predation rate and completion of life cycle on the eggs of CBM could also be considered as satisfactory indication of the potential use of C. carnea larvae for spider mite management. The inability of the predator larvae to complete the life cycle against motiles of CBM and DPM could help to devise a management plan for multiple/repeated releases of the predator larvae.