Predation Risk Effects of Lady Beetle IMenochilus sexmaculatus/I on the Melon Aphid, IAphis gossypii/I Glover

• Published in: Insects (Basel, Switzerland) Switzerland), 2023-12, Vol.15 (1)
• Main Authors: Lin, Xingming, Cui, Xiangxin, Tang, Jihong, Zhu, Jiawei, Li, Jinhua
• Format: Article
• Language: English
• Subjects: Aphididae; Behavior; Biological control; Influence; Insect pests; Ladybirds
• ISSN: 2075-4450; 2075-4450
• DOI: 10.3390/insects15010013

Biological control is an important method for pest management. Natural enemies not only prey on pests directly but also release predation risk cues to pests, causing physiological and behavioral changes in them, reducing their fitness, and ultimately leading to a decrease in their population. Aphis gossypii is an important insect pest of melon and many other crops worldwide. This study examined the predation risk effects of Menochilus sexmaculatus, which is abundant in agricultural areas of southern China, on A. gossypii. The results showed that the presence of M. sexmaculatus significantly altered the host preference of the aphids. The longevity of the aphids was shortened, and the reproductive period and offspring production were decreased significantly after exposure to M. sexmaculatus for 24 h. The enzyme activities of SOD and CAT were increased, and the content of MDA in aphids also showed an increase under the predation risk of M. sexmaculatus. Through a combined GC-MS and behavioral response experiment, the results showed that alkane compounds may mediate the predation risk. The results will offer an alternative strategy for utilizing these alkanes as repellents to manage aphids. Predation risk posed by natural enemies can alter pest performance. In our previous study, we found Menochilus sexmaculatus provides risk cues to melon aphids, resulting in increased numbers of winged aphids. However, the effects of predation risk on multiple traits including behavior, physiology, growth rate, and reproductive capacity of pests are not clear. This study examined the effects of predation risk on host preference, the activities of two important defense enzymes (CAT and SOD), longevity, and offspring production. The Y-tube trial results showed that the risk of M. sexmaculatus significantly altered the host preference of the aphids, leading to avoidance behavior. When exposed to M. sexmaculatus for a long period (24 h), the reproductive period and offspring production were significantly decreased, and adult longevity was significantly shortened. The defense enzyme activities of SOD and CAT, as well as the MDA content (which is considered a marker of oxidative stress and cellular damage) in the aphids, significantly increased under M. sexmaculatus risk. The compounds of M. sexmaculatus extracted with n-hexane and volatile compounds collected with HS-SPME were analyzed by GC-MS, and when combined with the behavior response experiment, the results showed that the