The effect of Hortia oreadica Groppo (Rutaceae) extracts on the growth, feeding and digestive enzymes of Anticarsia gemmatalis Hübner [1818] (Erebidae)

Abstract

The effects of four extracts of Hortia oreadica Groppo (Rutaceae) on the biological para- meters, nutritional indices, and activity of digestive enzymes of Anticarsia gemmatalis Hüb- ner [1818] (Erebidae) were evaluated. Newly hatched caterpillars were subjected to extracts from H. oreadica extracted with hexane (HE), dichloromethane (DE), dichloromethane fractionated with ethyl acetate (DEAE) and dichloromethane fractionated with dichlo- romethane (DDE) at concentrations 0, 100, 500 and 1000 μg ꞏ ml–1. The results showed that treatments significantly increased the cumulative mortality rate of A. gemmatalis and that HE 100 μg ꞏ ml–1 was the most effective, causing 92% of insects’ deaths. The period of larval development was significantly shorter with treatments HE 100 and 500 μg ꞏ ml–1 and longer with DEAE (all concentrations). The pupal weight was lower in the treatments HE 1000 μg ꞏ ml–1 and in all doses tested of the DEAE treatment. The morphological integrity of pupae and adults was not affected. The lowest values of relative food consumption rate, relative metabolic rate, and relative growth rate were observed in the HE 100 μg ꞏ ml–1 treat- ment. In most treatments, there was a reduction in the activity of total proteases, serine and cysteine proteases, and amylase. The results suggest that the HE extract of H. oreadica is the most efficient in controlling A. gemmatalis, due to the presence of deterrent metabolites that affect the insect’s digestion and nutrition and consequently promote adverse effects on its development and mortality.