Fig. 2

Suppression of cellular immune responses by four organic extracts of 14 bacterial isolates and its correlation with bacterial pathogenicity. Bacteria used in this assay were: Photorhabdus temperata Subsp. temperata ANU101 (‘Ptt’), Xenorhabdus hominickii ANU101 (‘Xh’), X. nematophila K1 (‘XnK1’), X. ehlersii KSY (‘Xe’),, X. nematophila SK1 (‘XnSK1’), X. nematophila SK2 (‘XnSK2’), Photorhabdus luminescens KACC12123 (‘Pl 193’), P. luminescens subsp. laumondii KACC12283 (‘Pl laum’), P. luminescens subsp. thracensis KACC12284 (‘Pl thra’), X. nematophila KACC12145 (‘Xn12145’), X. nematophila Mexico (‘XnM’), X. nematophila France (‘XnF’), X. bovienii (‘Xb’), and X. poinarii (‘Xp’). Their cultured broths were extracted with four different organic solvents: hexane (‘HEX’), ethyl acetate (‘EAX’), chloroform (‘CX’), and butanol (‘BX’). a Effects of organic extracts on hemocyte-spreading behavior. For each treatment, three independently prepared hemocyte mixtures were used. To determine the spreading behavior, 100 hemocytes were randomly chosen. b Effects of organic extracts on hemocyte nodulation in response to bacterial challenge. Each L5 larva of S. exigua was injected with bacterial extract (10 μg/larva) along with heat-killed E. coli (4 × 10⁴ cells). For each treatment, three replications were used with five larvae per replication. Arachidonic acid (AA, a catalytic product of PLA₂) was used to rescue the inhibition. Different letters above standard deviation bars indicate significant differences among means at Type I error = 0.05 (LSD test). c Correlations (r) between insecticidal activities of bacterial extracts (Fig. 1) and their immunosuppressive activities. Lines represent the best-fit regression