Safflower susceptibility and response to feeding by grasshoppers

Feeding by three grasshopper species, Camnula pellucida, Melanoplus packardii and Melanoplus sanguinipes, on three safflower (Carthamus tinctorius) lines for a 6-wk period from anthesis was monitored under field conditions. Ratings of feeding damage to different plant parts (leaves, floral parts, capitula, and peduncles) and measurements after termination of feeding (dry weight, seed yield, seed weight, seeds per capitulum, and capitula per row) were compared among grasshopper species and safflower lines. The Melanoplus species fed preferentially on leaves, floral parts, and capitula, while C. pellucida exhibited only peduncle feeding, which resulted in head clipping. Defoliation of 20 to 30% was associated with significant increases in total dry matter, seed yield, and number of capitula. Further defoliation resulted in decreases. The safflower lines differed in response to grasshopper feeding. S-208 was most susceptible to defoliation by grasshopper feeding, exhibiting decreased dry weight, seed yield, and capitula number. Lesaf 34C-00 was most tolerant and only M. packardii caused significant dry weight and seed yield reductions. Feeding by C. pellucida on this line resulted in an overall seed yield increase. Feeding by M. sanguinipes on Seedtec-5 resulted in yield increases of up to 16%. It appears that certain grasshopper species can increase seed yield in some safflower lines by stimulating the production of additional capitula. Therefore, moderate populations of such grasshoppers in fields of appropriate safflower cultivars do not necessarily require control.