Baculovirus-resistant Anticarsia gemmatalis responds differently to dietary rutin

The velvetbean caterpillar, Anticarsia gemmatalis ( Hubner) ( Lepidoptera: Noctuidae), the major soybean [ Glycine max ( L.) Merrill ( Fabaceae)] defoliator pest in Brazil can be controlled by a specific and virulent nuclear polyhedrosis virus ( AgMNPV). Flavonoids such as rutin ( quercetin 3-O-rhamnosylglucoside) were identified in soybean; it is known that this compound plays an important role in plant defense against lepidopteran pests. Studies were carried out to evaluate the biological and physiological activity of rutin ( 0.65 and 1.30%) on populations of A. gemmatalis resistant and susceptible to AgMNPV. Larvae from the resistant population were more negatively influenced by rutin, in comparison to larvae of the susceptible population, even with the addition of the lowest level of the flavonoid ( 0.65%) to the insect diet. The highest mortality ( 98%) was observed in the resistant population, when larvae fed on the diet containing 1.30% of rutin. Elongation of the feeding time, smaller initial larval weight, and pupal weight was observed on the virus-resistant and -susceptible populations after adding 0.65 and 1.30% rutin to the diet. Larvae of the resistant population to AgMNPV fed on diet plus rutin 0.65% were also less efficient in the conversion of ingested and digested food into biomass.