Investigations on Intra and Interspecific Interaction of Fall Armyworm Spodoptera frugiperda J E Smith with Native Insect Pests of Maize

Abstract

Intraspecific interaction (cannibalism) among different instar larvae of newlineSpodoptera frugiperda (J. E. Smith) revealed cent per cent cannibalism of 2nd instar newlinelarvae by 3rd, 4th and 5th instar larvae while the 3rd, 4th and 5th instar larvae experienced newline56.67, 53.33 and 46.67 per cent cannibalism respectively. However, among equal aged newlinelarvae, maximum cannibalism was observed among 2nd instar larvae (76.67 %) and the newlinelowest was observed among 5th instar larvae (50.00 %). Among equal aged larvae, newlinecannibalism was in linear relationship with density as evidenced incase of ten 2nd instar newlinev/s ten 3rd instar (100.00 and 63.33 %, respectively). With respect to interaction of S. newlinefrugiperda with Chilo partellus (Swinhoe), no egg predation was observed. Intraguild newlinepredation of S. frugiperda larvae on C. partellus was significantly higher when early newlineinstar larvae of C. partellus were attacked by different instars of S. frugiperda. The newlineinterspecific interaction between S. frugiperda and C. partellus larvae revealed a very newlinehigh degree of competitive displacement of C. partellus (100.00 % mortality of 1st and newline2nd instar larvae) by the 2nd, 3rd, 4th and 5th instar larvae of S. frugiperda. While, incase newlineof Helicoverpa armigera (Hübner), cent per cent egg predation by different larval newlineinstars of S. frugiperda was observed. The larval interaction among the two species newlineindicated that the S. frugiperda was dominant over H. armigera larvae as revealed by newline86.67, 96.67 and 90.00 per cent predation of 2nd instar H. armigera larvae by 3rd, 4th and newline5th instar S. frugiperda larvae, respectively. Whereas, H. armigera was dominant over S. newlinefrugiperda in its 4th instar by predating 83.33 and 53.33 per cent of 2nd and 3rd instar newlinelarvae of S. frugiperda. However, both the species were equally competitive when same newlinelarval instars (2nd v/s 2nd and 4th v/s 4th instar) of both the species were interacting. newlineAlthough, Cannibalism and intraguild predation boosted the larvae of S. frugiperda to reduce their competitors, it also caused negative effects on