State Key Laboratory of Biocatalysis and Enzyme Engineering, Center for Behavioral Ecology & Evolution, School of Life Sciences, Hubei University, Wuhan, China.
Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
Insect Sci. 2020 Dec;27(6):1276-1284. doi: 10.1111/1744-7917.12739. Epub 2020 Apr 13.
MEAM1 (Middle East-Asia Minor 1, "B" biotype) and MED (Mediterranean, "Q" biotype) are the two most destructive cryptic species of the Bemisia tabaci complex on the planet. Our previous studies have shown that MEAM1 outcompetes MED on cabbage; the underlying mechanism is unknown. In the Brassicaceae family, the glucosinolate-myrosinase defense system plays a crucial role in deterring feeding, inhibiting growth, and causing acute toxicity against a wide range of generalist herbivores. In the present study, we first compared the survival of MEAM1 and MED exposed to sinigrin (a glucosinolate) and myrosinase (an enzyme that degrades glucosinolates); we found that survival of both species was high in response to sinigrin alone but was near zero in response to sinigrin + myrosinase. We then used electropenetrography (electrical penetration graphs, EPG) to assess the feeding behaviors of MEAM1 and MED whiteflies on cabbage. The EPG results revealed that the mean duration of each potential drop (pd, indicating an intracellular puncture) was substantially longer for MED than MEAM1 on cabbage, indicating that the exposure to the toxic hydrolysates of glucosinolate and myrosinase is greater for MED than for MEAM1. We therefore conclude that differences in penetrating behaviors may help explain the different effects of cabbage on MEAM1 and MED whitefly species.
MEAM1（中东-亚洲小巽他群岛 1，“B”生物型）和 MED（地中海，“Q”生物型）是地球上烟粉虱复合种中最具破坏性的两个隐种。我们之前的研究表明，MEAM1 在白菜上竞争过 MED；其潜在机制尚不清楚。在十字花科植物中，硫代葡萄糖苷-黑芥子酶防御系统在阻止取食、抑制生长和对广泛的多食性植食性动物造成急性毒性方面起着至关重要的作用。在本研究中，我们首先比较了 MEAM1 和 MED 暴露于白芥子硫苷（一种硫代葡萄糖苷）和黑芥子酶（一种降解硫代葡萄糖苷的酶）后的生存情况；我们发现，两种物种单独暴露于白芥子硫苷时的存活率都很高，但单独暴露于白芥子硫苷+黑芥子酶时的存活率接近零。然后，我们使用电穿透图（电穿透图，EPG）来评估 MEAM1 和 MED 粉虱在白菜上的取食行为。EPG 结果表明，在白菜上，MED 的每个潜在下降（pd，表明细胞内穿刺）的平均持续时间明显长于 MEAM1，表明 MED 暴露于硫代葡萄糖苷和黑芥子酶的毒性水解产物的时间比 MEAM1 长。因此，我们得出结论，穿透行为的差异可能有助于解释白菜对 MEAM1 和 MED 粉虱物种的不同影响。
