Shapiro D I, Lewis E E, Paramasivam S, McCoy C W
Citrus Research and Education Center, Department of Entomology, University of Florida, Lake Alfred 33850, USA.
J Invertebr Pathol. 2000 Jul;76(1):43-8. doi: 10.1006/jipa.2000.4944.
Entomopathogenic nematode behavior is affected by the condition of their infected hosts. We hypothesized that nitrogen compounds released from infected hosts may be one factor affecting entomopathogenic nematode host-finding and infection behaviors. Our objectives were to (1) investigate the partitioning of nitrogen in Galleria mellonella (L.) infected by Heterorhabditis bacteriophora Poinar and (2) determine attraction and repulsion of H. bacteriophora to various quantities of nitrogen (ammonia). Volatile (ammonia), organic, and inorganic nitrogen forms were monitored during the course of infection. Approximately 0.052 mg of nitrogen was released from a single infected host as volatile ammonia. Most of the ammonia release was detected within the first 3 days postinoculation. Organic nitrogen increased during the course of infection, whereas inorganic nitrogen decreased. The net nitrogen change in the infected host consisted of a loss of approximately 47 mg, most of which was lost within the 1st week of infection. Accelerated loss of nitrogen early in the infection process was likely correlated with activity and growth of bacterial symbionts. Increased organic nitrogen was likely associated with nematode reproduction within the host. Attraction or repulsion of H. bacteriophora to nitrogen (ammonium hydroxide) was measured on agar quadrant plates. Nematodes were attracted to 16 and 160 microg of nitrogen and repelled by concentrations of 1600 and 8000 microg. Our data indicate that nitrogen released from H. bacteriophora-infected hosts attracts nematodes at lower levels (early in the infection) and repels them at higher concentrations (later in the infection process).
昆虫病原线虫的行为受其感染宿主状况的影响。我们推测，受感染宿主释放的含氮化合物可能是影响昆虫病原线虫宿主寻找和感染行为的一个因素。我们的目标是：（1）研究被嗜菌异小杆线虫感染的大蜡螟体内氮的分配情况；（2）确定嗜菌异小杆线虫对不同量氮（氨）的趋避性。在感染过程中监测挥发性（氨）、有机和无机氮形态。单个受感染宿主以挥发性氨的形式释放约0.052毫克氮。大部分氨释放是在接种后的前3天内检测到的。感染过程中有机氮增加，而无机氮减少。受感染宿主的净氮变化包括约47毫克的损失，其中大部分在感染的第一周内损失。感染过程早期氮的加速损失可能与细菌共生体的活性和生长有关。有机氮增加可能与宿主体内的线虫繁殖有关。在琼脂象限平板上测定了嗜菌异小杆线虫对氮（氢氧化铵）的趋避性。线虫被16微克和160微克的氮吸引，而被1600微克和8000微克的浓度排斥。我们的数据表明，嗜菌异小杆线虫感染的宿主释放的氮在较低水平（感染早期）吸引线虫，而在较高浓度（感染后期）排斥线虫。
