The distribution and morphology of various sensory
organs (sensilla) on the antenna and mouthparts of
Spodoptera littoralis larvae were investigated using
scanning electron microscopy. In this study we focused on
the morphological alterations of the antennal and
mouthparts sensilla of Spodoptera littoralis last instar
larvae reared on different host plants; alfalfa, cotton, and soybean leaves. Based on our results, we found that
sensillum chaeticum on the antenna was morphologically
affected by shifting the host plant since it became longer in those larvae reared on soybean and alfalfa leaves when
compared with those reared on cotton leaves. Furthermore,
several morphological variations were observed in sensilla
trichodea on the labium, mandibles, and labrum by shifting
the host plant. In addition, clear morphological changes
were observed in sensillum digitiformium on the maxillary
palps due to changing the host plant. On the other hand, no
morphological changes in antennal basiconic, trichodium
and styloconic galeal sensilla styloconica, maxillary
campaniform and placodeum sensilla were observed. Taken
together, these results showed that shifting host plants of
Spodoptera littoralis larvae induced plasticity and
morphological changes of the antennal and mouthparts
sensilla.