A survey for the parasitoids of the cotton fleahopper Pseudatomoscelis seriatus (Reuter) in its wild habitat : and the biology of two egg parasitoids of this pest

Abstract

Surveys for parasitoids of cotton fleahopper (CFH) Pseudatomoscelis seriatus (Reuter), were conducted on three wild host plants; Monarda punctata L., Croton capitatus Michx., and Oenothera speciosa Nutt. There were no parasitoids attacking nymph and adult stages. Erythmelus psallidis Gahan was parasitizing the eggs on all three host species while Anaphes sp. was parasitizing only when the eggs were on M. punctata plants. Sampling was conducted on all three host plants to study the phenology of the egg parasitoids, intensity of parasitism and effects of parasitism on CFH populations. Intensity of parasitism ranged from 1-62% depending upon the species of parasitoid, host plant and time of the year. There was no clear evidence to show that the parasitism by the two mymarid parasitoids causes any regulative effect on CFH populations. Both parasitoids were colonized in the laboratory on Lygus hesperus Knight eggs and their life history and biology were studied. Anaphes sp. had 2 larval instars and E. psallidis had 3. The first instar larva of E. psallidis is a type of insect larva never reported before. The threshold temperature for development and the thermal constant of heat requirement for complete development are reported for both species. The fecundity of Anaphes sp. was higher than that of E. psallidis. Longevity for both sexes of Anaphes sp. increased as the temperature decreased from 31°C to 10°C. Age of host egg had an influence up on success of parasitism by Anaphes sp. Anaphes sp. showed a functional response to host density and exhibited mutual interference in the laboratory. Cold storage of pupae delayed emergence of Anaphes sp. Anaphes sp. did not show differential preference for either CFH or Lygus eggs. Anaphes sp. females were attracted to volatile chemicals present in M. punctata flowers. More studies are needed to better exploit the existing parasitoid complex and in preparation for exploration for exotic nymphal and/or adult parasitoids to accomplish biological control of CFH.