Egg-Associated Germs Induce Salicylate Defenses but Not Render Plant Against a Global Invasive Fruit Fly Effectively

Germs associated with insect eggs can profoundly mediate interactions between host plants and herbivores, with the potential to coordinate plant physiological reactions with cascading effects on insect fitness. An experimental system was established including the oriental fruit fly (OFF, Bactrocera dorsalis) and tomato to examine the functions of egg-associated germs in mediating plant–herbivore interactions. OFF feeding resulted in significantly increased tannins, flavonoids, amino acids, and salicylic acid in the host tomato. These defensive responses of tomato were induced by the egg-associated germs, including Lactococcus sp., Brevundimonas sp., and Vagococcus sp. Tannins and flavonoids had no significant feedback effects on the pupal weight of OFF, while pupal biomass was significantly decreased by tannins and flavonoids in the germ-free treatment. Metabolome analysis showed that OFF mainly induced metabolic changes in carboxylic acid derivatives. Phenylalanine significantly induced downstream metabolic changes associated with phenylpropanoid accumulation. Finally, we conclude that the effects of egg-associated germs played an important role in facilitating OFF population adaptation and growth by mediating plant defenses, which provides a new paradigm for exploring the interaction of plant–pest and implementing effective pest biocontrol

Vehicle body’s mean position at different <i>β</i>.

(A) Vehicle body drops; (B) Vehicle body raises.</p

Maximum damping force required for shifting the vehicle body at different road excitation frequencies.

(A) Vehicle body raises; (B) Vehicle body drops.</p

Vehicle body’s mean position with different speeds and road levels.

(A) Vehicle body raises; (B) Vehicle body drops.</p

Vehicle body responses under sinusoidal road excitation.

(A) Displacement of the vehicle body; (B) Mean position of the vehicle body.</p

Median mode to low mode under the sinusoidal road.

(A) f = 2 Hz; (B) f = 5 Hz; (C) f = 10 Hz.</p

Ratio of energy consumption in extension travel and compression travel.

Ratio of energy consumption in extension travel and compression travel.</p

Mean position response of vehicle body under different road excitation.

(A) Varying road frequencies; (B) Varying road amplitudes.</p

Vehicle body’s mean position with different speeds and <i>β</i>.

(A) Vehicle body raises; (B) Vehicle body drops.</p

Schematic diagram of the vehicle height control.

Schematic diagram of the vehicle height control.</p