Abstract: 【Aim】 This study aims at exploring the host preferences and control effects of three common rice field dryinids (Echthrodelphax fairchildii, Gonatopus flavifemur and Haplogonatopus apicalis) on hemipteran pests. 【Methods】 Under the non-choice conditions, Nilaparvata lugens, Sogatella furcifera, Laodelphax striatellus, Nephotettix cincticeps and Nilaparvata muiri were used as hosts for the three dryinids, E. fairchildii, G. flavifemurand H. apicalis, to observe their host-feeding, parasitism activities and offspring development. And the selectivity of the three dryinids on planthoppers was also observed under the choice conditions. On the basis of above tests, the suitable host for each of the three dryinids was evaluated. The suitable hosts were used to study the longevity, host-feeding and parasitism activities for evaluating the control effects of these three dryinids. 【Results】 E. fairchildii could feed on and parasitize N. lugens, L. striatellus, S. furcifera and N. muiri, and the first three planthoppers were more suitable hosts than N. muiri, while N. cincticeps could not be fed upon or parasitized by E. fairchildii. G. flavifemur could feed on and parasitize four species of planthoppers: N. lugens and L. striatellus were highly adaptable hosts for G. flavifemur followed by S. furcifera and then N. muiri. N. cincticeps could be fed upon but not parasitized by G. flavifemur. For H. apicalis, S. furcifera was the most suitable host followed by L. striatellus, while the other three hosts could only be fed on but not parasitized by H. apicalis successfully. On the suitable hosts, H. apicalis females had the longest longevity and the highest total numbers of planthoppers fed upon and parasitized, then G. flavifemur, and finally E. fairchildii, and there was a slight fluctuation in the diurnal variations of host-feeding and parasitism amounts of the three dryinids. 【Conclusion】 E. fairchildii prefers to parasitize N. lugens, L. striatellus and S. furcifera, but its control effect is the lowest. G. flavifemur prefers to parasitize N. lugens and L. striatellus, and it has a medium control effect. H. apicalis prefers to parasitize S. furcifera with the best control effect. 

Key words:  Echthrodelphax fairchildii, Gonatopus flavifemur, Haplogonatopus apicalis; hemipteran pests, host selectivity, adult longevity, host feeding, parasitism