Theunis W, Aloali'i I
EU/SPC Taro Beetle Project, Honiara, Solomon Islands.
J Invertebr Pathol. 1999 May;73(3):255-9. doi: 10.1006/jipa.1999.4845.
Two morphological types of Bacillus popilliae, causal agent of the milky disease, have been isolated from taro beetles (Papuana spp, Coleoptera: Scarabaeidae). B. popilliae from P. woodlarkiana woodlarkiana (Papua New Guinea) was a type A1 with a small sporangium (4.1 x 1.6 microm) and a large spore (2.1 x 1.4 microm) and parasporal body (1.8 x 1.2 microm) that sometimes overlap. B. popilliae from P. uninodis and P. woodlarkiana laevipennis (Solomon Islands) was a type B2 with a small sporangium (2.8 x 1.3 microm), a small eccentric spore (1.1 x 0.7 microm), and no parasporal body. The infectivity of these B. popilliae to Papuana uninodis larvae was compared with two B. popilliae samples from Popillia japonica in injection tests. The hemolymph of P. uninodis supported the germination and growth of isolates from Papuana and P. japonica. Results were similar in third instars and adults. Highest infection (spores present) and mortality was caused by the isolates from Papuana: mortality reached almost 100% 4 weeks after injection of the B2 type B. popilliae with 40% of larvae and 52% of adults infected. Injection of type A1 caused lower mortality but a similar percentage infected. Of two A1 B. popilliae from P. japonica, one caused a mortality comparable to type A1 from Papuana but lower infection; an older isolate resulted in low mortality and only one infected larva. B. popilliae type A1 from P. woodlarkiana was produced in the Solomon Islands by injection of spores in P. uninodis. Thirty four percent of the injected larvae and 31% of the adults produced spores with an average yield of 3.2 and 0.8 x 10(9) spores/insect, respectively. Oral application of a single dose of 10(7) spores of the B. popilliae isolates from P. uninodis or P. japonica did not cause infection and similarly inoculation of the food with spores of B. popilliae type B2 did not result in infections. However, when different rates were applied to the food of second- and third-instar P. uninodis, the B. popilliae type A1 from P. woodlarkiana caused up to 15% infection and concentration-related mortality.
乳状病的病原体日本金龟子芽孢杆菌（Bacillus popilliae）已从芋头甲虫（Papuana spp，鞘翅目：金龟科）中分离出两种形态类型。来自新几内亚伍德拉克岛的伍德拉克芋头甲虫（P. woodlarkiana woodlarkiana）的日本金龟子芽孢杆菌为A1型，其芽孢囊小（4.1×1.6微米），孢子大（2.1×1.4微米），伴孢体（1.8×1.2微米），有时相互重叠。来自单瘤芋头甲虫（P. uninodis）和所罗门群岛的光滑伍德拉克芋头甲虫（P. woodlarkiana laevipennis）的日本金龟子芽孢杆菌为B2型，其芽孢囊小（2.8×1.3微米），偏心小孢子（1.1×0.7微米），无伴孢体。在注射试验中，将这些日本金龟子芽孢杆菌对单瘤芋头甲虫幼虫的感染力与来自日本丽金龟（Popillia japonica）的两个日本金龟子芽孢杆菌样本进行了比较。单瘤芋头甲虫的血淋巴支持来自芋头甲虫和日本丽金龟的分离株的萌发和生长。在三龄幼虫和成虫中的结果相似。来自芋头甲虫的分离株引起的感染（有孢子存在）和死亡率最高：注射B2型日本金龟子芽孢杆菌后4周，死亡率几乎达到100%，40%的幼虫和52%的成虫被感染。注射A1型导致较低的死亡率，但感染百分比相似。来自日本丽金龟的两个A1型日本金龟子芽孢杆菌中，一个引起的死亡率与来自芋头甲虫的A1型相当，但感染率较低；一个较老的分离株导致低死亡率，只有一只感染幼虫。通过将孢子注射到单瘤芋头甲虫体内，在所罗门群岛产生了来自伍德拉克岛的A1型日本金龟子芽孢杆菌。34%的注射幼虫和31%的成虫产生了孢子，平均产量分别为每只昆虫3.2×10⁹和0.8×10⁹个孢子。口服单剂量10⁷个来自单瘤芋头甲虫或日本丽金龟的日本金龟子芽孢杆菌分离株的孢子不会引起感染，同样，用B2型日本金龟子芽孢杆菌的孢子接种食物也不会导致感染。然而，当以不同剂量施用于二龄和三龄单瘤芋头甲虫的食物时，来自伍德拉克岛的A1型日本金龟子芽孢杆菌引起高达15%的感染和与浓度相关的死亡率。
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