Facultative bacterial endosymbionts benefit pea aphids Acyrthosiphon pisum under heat stress
Facultative bacterial endosymbionts benefit pea aphids Acyrthosiphon pisum under heat stress
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DOI：
10.1046/j.1365-2311.2002.00393.x
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发表时间：
2002-04-01
影响因子：
2.2
通讯作者：
Purcell, AH
中科院分区：
文献类型：
--
作者：
Montllor, CB;Maxmen, A;Purcell, AH
1.加州的豌豆蚜虫自然种群包含至少两种兼性细菌次级共生体（豌豆蚜虫次级共生体，PASS或豌豆蚜虫立克次体，PAR），其频率范围遍及整个州。两个没有这些兼性伴体的豌豆蚜无性系在实验室中作为1日龄幼虫在39 ℃下热应激约4 h后，在最后一次蜕皮后的前8天内不能繁殖.然而，人工感染PASS的蚜虫能够产生高达48%的未受到热应激的PASS阳性蚜虫所产生的后代的正常补体。人工感染PAR的无性系在热胁迫后表现出的优势不如PASS.在没有PASS或PAR的蚜虫中，热应激将细菌细胞（其中专性初级共生体Buchnera驻留）的数量减少到非热应激蚜虫的7%，而只有PASS的蚜虫保留了70%的细菌细胞。接种PAR而不接种PASS的蚜虫体内细菌数量减少到对照的42%.当幼虫热应激作为老龄（5天），出现了类似的模式，虽然热应激的影响是不那么极端。含有PASS的克隆产生了最多的后代，是没有PASS或PAR的蚜虫的3到14倍。与无兼性共生体的蚜虫相比，仅具有PAR或PASS和PAR共同作用的蚜虫的优势降低或没有优势。蚜虫的所有克隆，已热应激为晚龄生下了一个变量的死产后代。没有兼性共生体的蚜虫产生的死胎幼虫最多。田间研究表明，夏季在加州采集的蚜虫中PASS的发病率高于2-4个月前从相同地点采集的蚜虫。在三个广泛分布的地点中，有两个差异显著。
1. Natural populations of pea aphids in California contain at least two facultative bacterial secondary symbionts (pea aphid secondary symbiont, PASS, or pea aphid rickettsia, PAR) in a range of frequencies throughout the state.2. Two pea aphid clones without either of these facultative associates failed to reproduce in the first 8 days after the final moult if they had been heat-stressed for a period of about 4 h at 39 degreesC as 1-day-old larvae in the laboratory.3. Aphids infected artificially with PASS, however, were able to produce up to 48% of the normal complement of offspring produced by PASS-positive aphids that had not been heat-stressed. Clones infected artificially with PAR did not have the same advantage as those with PASS after heat stress.4. In aphids without PASS or PAR, heat stress reduced the number of bacteriocytes (in which the obligate primary symbiont, Buchnera , resides) to 7% of non-heat-stressed aphids, while aphids with only PASS retained 70% of their bacteriocytes. Bacteriocytes in aphids with PAR but not PASS were reduced to 42% of controls.5. When larvae were heat-stressed as older instars (5 days old), a similar pattern emerged, though the effect of heat stress was less extreme. Clones containing PASS produced the most offspring, three to 14 times as many as aphids without PASS or PAR. Aphids with PAR only, or PASS and PAR together, had reduced or no advantage over aphids without facultative symbionts.6. Aphids of all clones that had been heat-stressed as later instars gave birth to a variable number of stillborn offspring. Aphids without facultative symbionts produced the most stillborn larvae.7. Field studies showed a higher incidence of PASS in aphids collected in California in summer compared with aphids from the same sites collected 2-4 months earlier. The difference was significant in two of three widely dispersed locations.