NUCLEAR POLYHEDROSIS-VIRUS OF THE GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) - POTENCY AND EFFECTS OF SELECTED ADJUVANTS ON INSECT FEEDING-BEHAVIOR

The potency of two formulations of the nuclear polyhedrosis virus of t he gypsy moth (LdMNPV) was evaluated in the laboratory. Both formulati ons were prepared with the same batch of LdMNPV produced in live insec ts by the USDA Forest Service. A Forest Service-recommended tank-mix p reparation (LdMNPV, molasses, ultraviolet light screen, and sticker in water) was found to be about 20 times more potent than an experimenta l wettable powder preparation. The wettable powder also deterred feedi ng, the 20-fold difference in potency, though, is based on actual dose s consumed. The addition of a stilbenedisulfonic acid derivative, Blan kophor BBH, to the tank-mix and wettable powder preparations at a conc entration of 1% (wt./vol.) reduced the LD(50)s by 42- and 214-fold, re spectively. Blankophor BBH was also a moderate feeding deterrent to gy psy moth, Lymantria dispar (L.), larvae which could limit its efficacy as an enhancer of the virus. However, the addition of molasses to Bla nkophor BBH at least partially overcame the feeding deterrence. Other adjuvants were also tested for effects on larval feeding behavior, inc luding Bond (sticker), Lignosite AN (ultraviolet light screen), and Ca rrier 244 (spray carrier). Of the materials tested, molasses was the s trongest feeding stimulant, followed by Carrier 244. Bond and Lignosit e AN had no detectable effect on feeding behavior in these tests. Thes e data demonstrate the importance of monitoring potency during any for mulation process, the possibility of enhancing the virus with adjuvant s, and of understanding the effects of adjuvants on feeding behavior.