Search Results

1 - 3 of 3 items :

  • "sexual forms" x
Clear All

Abstract

For over a decade, our research group has studied the biology of the native bumblebee, Bombus atratus, to investigate the feasibility of using it to pollinate crops such as tomato, strawberry, blackberry and peppers. Traditionally, captive breeding has depended on the use of captured wild queens to initiate the colonies. The goal of the current work is to investigate conditions required to produce new queens and drones in captivity. In this study, 31 colonies were evaluated under either greenhouse or open field conditions over a 15 month period. A total of 1492 drones (D) and 737 gynes (G, i.e., virgin queens) were produced by all colonies, with 16 colonies producing both drones and gynes (D&G), 11 producing only drones (D) and 4 producing neither. Some of the D&G colonies had more than one sexual phase, but no colonies produced exclusively gynes. More drones and fewer gynes were produced per colony under greenhouse conditions with the highest number of drones produced by D&G colonies. The numbers of immature stages per cell declined in colonies as increasingly more resources were allocated to the production of gynes and the maintenance of increased nest temperature.

Abstract

The rose aphid, Macrosiphum rosae, is one of the most important pests on roses in the world and it causes economic damage. In this study, biology, seasonal population dynamics, and status of natural enemies of the rose aphid were studied. Seasonal population dynamics was studied by randomly sampling 10 shoots every week in two locations of Isfahan, Iran. Rose aphid with a high population density, both in spring (April and May) and in autumn (November), was observed on roses. The results showed that the rose aphid overwinters as parthenogenetic females and nymphs. This aphid migrates to a secondary host, Dipsacus fullonum (Dipsacaceae), in summer due to poor food quality of rose plants. Since sexual form and egg of the rose aphid were not observed in Isfahan, it is probably anholocyclic species with host alternation in this area. Natural enemies of the rose aphid include four species of Coccinellidae, three species of Syrphidae, two species of Chamaemyiidae, one species of Chrysopidae, a few species of Anthocoridae and Miridae, and one species of Cantharidae. One species of ectoparasite mite of Erythraeidae was also collected. In addition, four species of parasitoid wasps, Braconidae, were collected.

three individuals derived from pyrethroid-susceptible, kdr -SS, lineages were the SA27 clone. All kdr -SR oviparae were determined to be the SA3 clone. The kdr- heterozygous SA3 clone was collected from widely separated locations within the main cereal-growing region of Ireland, in Counties Carlow, Cork and Wexford ( Table 2 ). Table 2 Field origin, genetic identities and treatment history of all S. avenae individuals with observed capacity to produce sexual forms and lay eggs following the pyrethroid bioassay Field Location Kdr Genotype Oviparous capacity