## 4 Discussion
### The Role of Honeydew in Egg Parasitism  
We found that the BPH on IR62 produced less honeydew and the honeybee had higher proportions of acidic xylem-derived materials than honeybee produced on IR64. Honeydew is a sweet and sticky substance that contains sugars [78]. However, the honeybee of planthoppers also contains a range of other chemicals including proteins of insect, plant and bacterial origin [79], plant hormones, including feeding inhibitors [80], and plant defense elicitors of insect or microbial origin [76; 79]. BPH honeybee has recently been shown to also contain microbial symbionts that enhance rice defenses against insects and diseases, which may ultimately induce rice volatiles that attract natural enemies [76]. Honeydew is a rich source of nutrients for the insects that consume it [34; 45; 81]. Indeed, recent evidence suggests that honeydew is often the main food source for aphid parasitoids even in the presence of diverse nectar sources [35]. Furthermore, honeydew may include host-location kairomones or function as a stimulator of oviposition for parasitoids [32; 45; 82].  
We found no evidence that honeydew plays a role in the attraction of _Oligosita_ spp to infested plants (Figure 4C,D, Table 2). However, honeydew did play a role in parasitism by _Anagrus_ spp. (Table 2). We found that egg parasitism by _Anagrus_ spp. was higher on plants with honeydew than on plants without honeydew; however, the effect was only apparent for plants in high nitrogen pots/plots. Because _Anagrus_ spp. parasitized more eggs on IR64 (Figure 3A,B), we expected that honeydew from IR64 would also be most attractive to the species. However, the parasitism of eggs in high-nitrogen plants (either IR62 or IR64) with IR62 honeybee was consistently higher than in high-nitrogen plants with IR64 honeydew (Figure 4A,B). However, in our experiments, we used equal amounts of honeydew on susceptible and resistant plants; under natural conditions, the quantities of honeydew on IR62 plants would be considerably lower than on IR64 plants (Table 1)-which may explain why _Anagrus_ spp. parasitized more eggs in the IR64 plots. _Anagrus_ spp. may also prefer plants based on the availability of nutrients in the associated honeydew, as suggested by the relatively strong nitrogen effect in the experiment (Figure 4A,B, Table 2).  
The mechanisms leading to higher parasitism on plants treated with IR62-derived honeydew compared to equal amounts of IR64-derived honeybee are difficult to suggest. Parasitoid behaviors are complex and it may be that IR62-derived honeydew provides nutrients to parasitoids in a more diluted form (because xylem-derived honeybee contains more water) possibly avoiding the need to clean mouth and body parts [78] and reducing searching and handling times. IR62 honeybee may also have higher levels of JA, specific volatiles, or sucking inhibitors that directly or indirectly attract parasitoids. As indicated by [PERSON] et al. (2006) [37], the nature of volatiles emitted from rice plants is difficult to predict and the volatile blends emitted are not grouped according to resistance levels. Future studies that compare several resistant and susceptible varieties for their honey-related effects on parasitism are required to better understand these complex interactions and to test general hypotheses concerning egg parasitism in crops of resistant rice. However, our results do indicate that _Anagrus_ spp. respond to honeydew in high-nitrogen plots, and that honeydew from resistant rice is not necessarily unattractive or otherwise less beneficial to egg parasitoids. Furthermore, higher egg parasitism associated with IR62-derived honeydew (Figure 4A,B), when these plants become more vulnerable under high soil nitrogen regimes, may compensate for the normally low attraction of parasitoids to resistant IR62 plants (Figure 2).