A novel gene associated with intraspecific predation in Spodoptera litura larvae

Abstract

We investigated the inheritance of cannibalistic behavior in larvae of the common cutworm, Spodoptera litura. The fact that artificial selection of non-cannibalistic animals over 17 generations resulted in decrease of their cannibalistic behavior is clearly the proof of their inheritance of this behavior. Average frequency of cannibalism in selected larvae (3.2%) was significantly lower than that in non-selected larvae (24.5%). We employed the differential display RT-PCR analysis to evaluate differences in gene expression in the brains between selected and non-selected lines, and identified one gene whose expression was significantly higher in non-selected line larvae than that in selected line larvae. The identified gene with 779 bp was a novel gene without a major sequence homology with any reported genes. This gene was expressed in several tissues, fat body, brain, and hemocytes, among which the highest expression was observed in the brain. Further, the expression of this gene was very low in the brain of normally fed larvae but starvation significantly enhanced its expression only in the non-selected larvae. These results imply the possibility that the gene identified in the present study contributes to initiating cannibalistic behavior of S. litura larvae although the detailed function of this gene is unknown at present.

Predatory cannibalism in Drosophila melanogaster larvae

“…In highly gregarious locusts and crickets cannibalism is an important source of protein and salts, which allows the cannibals to survive longer and migrate farther; cannibalism avoidance is an important factor driving their mass migrations 5,7 . The rapid response to artificial selection for reduced incidence of intraspecific predation in Spodoptera caterpillars 23 demonstrates that it is a heritable trait with substantial genetic variation. Although its benefits are unclear, cannibalism in Spodoptera carries a cost in terms of disease transmission 24 .…”

Male-killing virus in a noctuid moth Spodoptera litura

“…For example, sibling cannibalism, i.e., the feeding of unhatched male eggs by hatched female larvae, increases the fitness of surviving larvae in some insect species harboring male killers ( 9 ). Although there are no records of S. litura larvae feeding on eggs, it is apparent that cannibalism between larvae occurs ( 41 ). This suggests that egg consumption probably occurs and contributes to the fitness of SlMKV-infected S. litura females.…”

Effect of Rearing Methods on <i>Spodoptera litura</i> (F.) under Laboratory Condition

“…Previous studies reported that non motile (egg and pupae) or less motile stages (younger larvae) are more prone to cannibalism by older larvae and more on natural host when compare to artificial diet in mass rearing. Ryuda et al (2008), favored to rear larvae separately on artificial diet to avoid cannibalism in tobacco cutworm. Separate or singly rearing on artificial diet in vials, is a good option to avoid cannibalism in laboratory rearing.…”