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Simple Summary: Maximizing the combination of biological control by natural enemies and plant resistance is a key strategy for controlling aphids in various crop systems. In our study, some alfalfa cultivars were found to have resistance to the pea aphid, Acyrthosiphon pisum, a dominant pest in alfalfa fields in northwestern China. In addition, natural enemies were able to significantly suppress this aphid, regardless of the resistance level of the nine cultivars tested. Moreover, the biological control efficacies of predators, parasitoids, and mixed populations of natural enemies were 85%, 42%, and 88%, respectively. Conservation of natural enemies in the field is an ecologically sound and efficient approach to the management of the pea aphid in alfalfa crops. The pea aphid, Acyrthosiphon pisum Harris, is a major pest of alfalfa in northwestern China. However, the roles of different groups of natural enemies in combination with aphid-resistant cultivars in the suppression of the pea aphid have not been clarified under field conditions. In this study, we used experimental cages to better understand the top-down (natural enemies) and bottom-up (nine alfalfa cultivars) biological processes, as well as the individual roles of the two processes, in the control of the pea aphid. There was a significant difference in resistance among cultivar classes revealed when natural enemies were excluded. The functional contribution of top-down suppression was higher than the bottom-up process, with natural enemies significantly suppressing aphid populations, regardless of the resistance level of different alfalfa cultivars. The mean biological efficacies of predators, parasitoids, and mixed populations of natural enemies were 85%, 42%, and 88%, respectively. Overall, our study indicated that natural enemies play a critical role in suppressing aphid populations, especially in the summer, whereas cultivar resistance did not combine effectively with natural enemies to inhibit the growth of aphids. Conservation biological control (CBC) can be implemented in the alfalfa production regions in northwestern China to reduce the overreliance on insecticides for the control of pests and mitigate their harmful effects on humans, ecosystems, and biodiversity. [ABSTRACT FROM AUTHOR]

Host plants indirectly affect parasitoid life-history traits via parasitoid hosts. Here, we evaluated the life-history traits of the parasitoid Aphelinus varipes emerging from the green peach aphid, Myzus persicae (Hemiptera: Aphididae), feeding on five commercially important vegetables.The results showed that A. varipes fed upon and parasitized maximum number of aphids grown on chili pepper, and least on cabbage. The emergence rate was the highest on chili pepper (100%) and lowest on crown daisy (71.1 ± 2.17%). Aphelinus varipes developed fastest on hosts reared on chili pepper (12.9 ± 0.02 d) and slowest on aphids reared on cabbage (14.1 ± 0.02 d).The body weight and body size of emerging wasp parasitoids and aphids were greatest on chili pepper and lowest on cabbage. Aphid body size positively affect parasitism, development time, and body size of the parasitoid. In conclusion, our results showed that the parasitoid A. varipes had variable life-history parameters, depending on the host plant species and host body size.The effects of host plant species on performance of M. persicae and its parasitoid A. varipes are discussed, along with the potential of using A. varipes to control M. persicae on different plants. [ABSTRACT FROM AUTHOR]

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a destructive pest on tomato, has invaded most Afro-Eurasian countries. Recently invaded by the pest, most tomato crops in greenhouses and open fields in Tajikistan are currently suffering major damage. While failure in management using chemical insecticide has been frequently observed, alternative options such as biological control is urgently needed. In this study, we evaluated the effectiveness of the common green lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) against T. absoluta. In controlled laboratory conditions, C. carnea showed high predation rate on both T. absoluta eggs (i.e., 36 ± 2 eggs within 24 h and 72 ± 4 eggs within 48 h) and larvae, especially it can attack the larvae both inside and outside the leaf galleries (i.e., an average of 22% of the larvae was killed inside, and an average of 35% was killed outside). In a cage exclusion experiment, T. absoluta showed relatively low larval density in the cages with pre-fruiting release of C. carnea, whereas the larval density was four to six times higher in the "no release" cages. In the "post-fruiting release" cages, the pest population that had already built up during the pre-fruiting stage eventually crashed. In an open-field experiment, the tomato crops in control plots were fully destroyed, whereas low levels of larvae density and damage were observed in the biocontrol plots. Moreover, the field release of C. carnea resulted in significantly higher tomato yield than those without release, despite no differences between the "pre-fruiting release" and "post-fruiting release" treatments. We conclude that the local commercial biocontrol agent C. carnea could be promising for the management of T. absoluta in Tajikistan. It is also one of the first reports showing the management of T. absoluta using a lacewing species. The effectiveness should be validated by further field trials in larger area of commercial crops and various locations. [ABSTRACT FROM AUTHOR]

Background: The globose scale (GS), Sphaerolecanium prunastri (Boyer de Fonscolombe) (Hemiptera: Coccoidea), has invaded wild apricot forests in their native range in Central Eurasia threatening the ancestral germplasm resource. Biological control efficacy of the harlequin ladybird, Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) against the globose scale was assessed in laboratory and field experiments. Results: In the laboratory, Harmonia axyridis has a high feeding capacity on GS with numbers consumed daily increasing with temperature (15, 20, 25, 30, 35 °C), reaching an upper asymptote of 160–200 scales per day. In field cage experiments, efficacy of biological control (EBC) against first instar (49–99%) and second instar nymphs (20–80%) increased with GS density. When ants were present, control efficiency was reduced by 10–15%. In open-field experiments without cages, EBC was comparatively lower regardless of duration and how H. axyridis were released whether as adults, eggs cards or a mixture of adults and eggs cards. Conclusions: In the long term, biological control with this ladybird predator could be considered as part of an IPM program package that includes banning or delaying mowing grass and understory plants in the forests that offer pollen and nectar for natural enemies. [ABSTRACT FROM AUTHOR]