Abstract: This study aims to explore the biological characteristics of Coccinella transversoguttata, a native dominant natural enemy insect in Xizang that preys on the larvae of Myzus persicae (Sulzer), with the intention of providing a theoretical foundation for the utilization of C. transversoguttata in controlling M. persicae. The life history, morphological features, life habits, developmental durations, and survival rates of C. transversoguttata at various developmental stages were meticulously observed and recorded both in the field and under laboratory conditions. Additionally, the predatory capabilities of different instar larvae and adults of C. transversoguttata on M. persicae at different densities were determined. The Holling type Ⅱ model was employed to fit and calculate the predation function of different instars of C. transversoguttata on M. persicae. C. transversoguttata has two generations annually in Lhasa, and overwinters at the adult stage. In the field, the peak oviposition period ranges from late April to mid-May, the peak hatching period is from early May to early June, the peak pupation period extends from late May to late June, and the peak adult emergence period is from early June to mid-July. Under laboratory natural conditions, the durations of eggs, the 1^st―4^th instar larvae, pupae, and adults of C. transversoguttata are 1.996, 2.395, 1.729, 1.310, 3.434, 4.901, and 55.838 days, respectively. The survival rates of eggs, the 1^st―4^th instar larvae, and pupae are 100.00%, 85.00%, 88.33%, 80.00%, 71.67%, and 61.67%, respectively, and the oviposition period lasts for 30―60 days. The predatory functional responses of different instars of C. transversoguttata to M. persicae all conform to the Holling type Ⅱ model. The fitting disc equation revealed that the 4^th instar larvae of C. transversoguttata exhibited the strongest predatory ability (a′/T_h) towards M. persicae larvae, with a value of 284.03; the largest maximum daily theoretical predation amount (1/T_h) of 263.16, and the shortest time required to handle a single prey of 0.0038 days. The 1^st instar larvae of C. transversoguttata had the lowest predatory ability (a′/T_h) towards M. persicae, with a value of only 34.19. Moreover, the predation of C. transversoguttata on M. persicae was simultaneously influenced by its own density, decreasing with the increase of its own density. These results demonstrate that C. transversoguttata holds great potential for the biological control of M. persicae. This research can offer a theoretical basis for more efficient utilization of C. transversoguttata resources and the accurate evaluation of the biological control potential of C. transversoguttata against M. persicae.

Key words: Coccinella transversoguttata, Myzus persicae, biological characteristics, predatory capacity, interference response