The Effect Induced By Phyllotreta Striolata Feeding On The Growth And Development Of Plutella Xylostella

We researched the plant-mediated indirect effects of striped flea beetle (SFB), Phyllotreta striolata (Fabricius) on the diamondbak moth (DBM), Plutella xylostella (L.) in six cruciferous vegetables species,Brassica juncea (L.), Brassica parachinensis Bailey, Brassica alboglabra Bailey, Brassica chinensis (L.), Brassica oleracea (L.) and Raphanus sativus (L.).We examined the parameters of feeding area, the growth and the oviposition preference of DBM after setting the levels by the number and feeding time of SFB respectively.The results were as follows:1. The effect induced by SFB on the feeding area of DBM:The effect induced by SFB on the feeding of DBM is obvious. In general, SFB feeding on small amount or short period will stimulate the feeding of DBM's larvae on corresponding leaves, otherwise will be inhibited; And the carrying capacity of different host or different integrity of the leaf (whether was fed by SFB) is different. The carrying capacity of B. Juncea, B. Parachinensis, B. chinensis and R. sativus were lower than B. alboglabra's and B. oleracea's, the leaf fed by SFB is weaker than the full leaf; Compared with the number of SFB, the feeding time of SFB has greater influence on the feeding of DBM.2. The effect induced by SFB on the growth and development of DBMHost species has a significant impact on the fecundity and larval duration of DBM,it has a impact on egg duration, pupal weight and survival rate, but not significant, and it has no effect on pupa duration. The fecundity of DBM on the B. Juncea, B. parachinensis, B. chinensis and R.sativus which SFB and DMB perfer feeding is greater, and the larval duration is shorter. Feeding by different number of SFB has significant difference on the fecundity of DBM, but the other biological parameters were not significant difference. A small amount of SFB's feeding will stimuate egg-laying of DBM, when the amount becomes big, it will be inhibited. SFB feeding on different days only has significant influence over the pupal weight of DBM, and hasn't any significant influence on the other biological parameters. The pupal weight of DBM decreased when the day of SFB feeding increased.3. The effect induced by SFB on the oviposition preference of DBMHost species to some extent affects the oviposition choice of DBM adult. The female adult of DBM prefered to lay their eggs on the B. Juncea, B. parachinensis, B. chinensis and R. Sativus, while the number of eggs laid on B. Alboglabra and B.oleracea was less clearly. The number of SFB is an important factor to effect the oviposition choice of DBM, but on different hosts the degree of impact is varying. A small amount of flea beetle feeding will increase the DBM's oviposit probability on the B. parachinensis ,B. Chinensis, R. sativus and B. alboglabra, but the number of SFB in excess of 5, 5, 7 and 9 separately will inhibit. SFB's feeding will reduce DBM's oviposit probability on B. Juncea, but has no effect on B.oleracea. In addition, SFB feeding on different days has a little influence on DBM's oviposition preference.