Isolation, fractionation, identification and bioassay studies of the pheromone of the maconellicoccus hirsutus (green, 1908)

Maconellicoccus hirsutus (Green, 1908) is one of the invasive pests known to infest the agricultural crops of Vadodara, Gujarat. Large amount of pesticides are in use to control this pest which ultimately pose threat to both environment and mankind. So eco-friendly measures are required to limit the invasion of this pest. Hence the objective is to isolate the pheromone from Maconellicoccus hirsutus to uncover its different components through GC-MS along with the bioassay studies. Pheromone was isolated from the species through adsorbent method, and the volatiles were then subjected to GC-MS for fractionation. Crude extracts was further employed for behavioral bioassay to identify the nature of the pheromone. Combined result of GC and GC-MS indicated the presence of phenolic component in the extract. Additionally, observations from bioassay studies confirmed it as sex pheromone where attractive index of males towards volatiles was higher (0.88) than the females. Hence, identification of different pheromonal components will be helpful in synthesizing chemical analogues and their use in controlling the concerned pest in an eco-friendly way.

Structure-Activity Study with Haloalkane Attractants of Western Corn Rootworm (Coleoptera: Chrysomelidae) Larvae Using a Behavioral Bioassay

A two-choice laboratory behavioral bioassay was used to compare the dose-dependent responses of second-instar western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae to a series of structurally-related haloalkanes, including ones with different halogens, degree of halogen substitution, chain length, and degree of saturation. Disubstituted bromine and iodine analogs of dichloromethane attracted larvae at all doses tested, including 0.5, 1.0, 2.0, and 4.0 mg. Dibromomethane attracted significantly more larvae than dichloromethane at the lowest dose tested (0.5 mg). Analogs of dichloromethane with more chlorine substitutions attracted significantly fewer larvae than dichloromethane at most doses tested except for chloroform, which attracted significantly more larvae than dichloromethane at the lowest dose tested (0.5 mg). Although larvae were repelled by the two highest doses of 1,1-dichlorobutane tested (2.0 and 4.0 mg), orthogonal contrasts revealed no trend in responses of larvae to increasing doses of it or any of the other chain length analogs tested, 1,1-dichloroethene is an unsaturated analog of 1,1-dichloroethane, and orthogonal contrasts revealed a positive linear trend for responses of larvae to increasing doses of it.