Mate location responses of male and female solitary-reared locusts that had either experienced no crowding or that had been crowded for varying periods were studied in a flatbed wind tunnel. Two hypotheses were explored: that both sexes of this phase of the locust participate in locating the other by using a combination of chemical and visual signals, and that individuals that experience some crowding (i.e., undergo varying levels of phase shift) can compete effectively with their solitary counterparts in mate location and mating. Our results confirm that both male and female solitarious locusts actively participate in mate location, although the former is the more aggressive partner. The responses of the insects are stronger when a visual cue is provided with the olfactory signal. Crowding of solitary-reared adults enhances their responsiveness to the other sex in the absence and presence of the visual cue. This phenomenon may constitute one of several mechanisms that are involved in recruiting solitary individuals into gregarizing groups and facilitating the spread of gregarious characters across a reproductively active solitarious population.

The responses of adult solitarious desert locust to odors from a host plant were evaluated in a two-choice wind tunnel. Solitarious desert locusts collected from the field (Red Sea Coast) were more attracted to volatiles from pottedHeliotropium ovalifoliumin scotophase than in photophase. The attraction towards the host plant odors rather than to clean air, in both photophase and scotophase, concurs with previous observations on oviposition preferences near these plants. Diel behavioral activity patterns of adult solitarious desert locustsSchistocerca gregaria(Forskål) that were collected from the field in Port Sudan were investigated by monitoring, scanning, resting, taking off, and walking/running in a wind tunnel. Solitarious locusts that had been propagated in the laboratory for 20 generations were also observed for comparison. In both groups of locusts, insects were significantly more active after sunset and this activity attained peak level at 1-2 hours after dusk. Of the two groups, solitarious locusts collected from the field were significantly more active. In the scotophase, the former traversed distances that were about seven times those covered by laboratory-reared locusts. Overall, the results show that the repertoire of behavioral activities of solitarious locusts is maintained in laboratory-reared insects, albeit at a lower level. The implications of these observations in the behavioral ecology of the desert locust are discussed.

A field trial was conducted at Shambat Research Station FarmKhartoum, Sudan during 2011/2012 and 2012/ 2013 winter seasons, toevaluate the activity and selectivity of the herbicide Clethodim (Selectsuper120 EC ) for weed control in alfalfa. The herbicide was tested at0.036, 0.048 and 0.060 kg a.i. /fed, as post- emergence treatments, 3weeks after sowing of alfalfa. The most prevailing weed species weresweet signal grass {Brachiaria eruciformis (Sm) Grieseb.}, purple nutsedege (Cyperus rotundus L.) and croton {Chrozophora plicata (Vahl.)A. Juss. Exspreng}. Results showed that the losses due to competition indry matter yield of alfalfa were 57% and 37% in the first cut, in the firstand second seasons, respectively. All herbicide treatments were highlyselective to the crop. The herbicide at all rates tested gave consistent andeffective control of grassy weeds (81% – 100%). Most of the herbicidetreatments significantly increased alfalfa fresh and dry matter yields incomparison with the weedy check

An experiment was conducted at the Sugarcane ResearchCenter, Guneid, during 2004/05 and 2005/06 seasons to evaluate theefficacy of some foliar herbicides on the growth of purple nutsedge(Cyperus rotundus L.) and to assess the effect of the treatments on theproduction and viability of tubers. The products tested were Krismat 75WG (Trifloxysulfuron-sodium+ametryn) at three rates (1.79, 2.38 and2.98 kg product ha-1 ) and Envoke 75 WG (Trifloxysulfuron-sodium) atthree rates (0.025, 0.030 and 0.035 kg product ha-1 ). Ametryn (Gesapax50 FW) + Atrazine (Gesaprim 50 FW) were used at the recommendedrates (3.81 L + 3.81 L product/ha), as a control. The results showed thatstatistically significant control of purple nut-edge was attained by allchemical treatments compared with the untreated check. Envoke 75 WGat 0.035 kg product/ha and the standard mixture of Gesapax + Gesaprimat its recommended rate significantly (P=0.05) reduced the number ofpurple nut-sedge compared with the untreated check. Gesapax +Gesaprim gave the lowest number of green leaves per plant. Envoke 75WG and Krismat 75 WG showed consistent reductions in tuberproduction and sprouting. Therefore, their successive application maylead to persistence and continuous reduction in the population density ofpurple nut-sedge in the fields of sugarcane.