Development and population growth of Lygus hesperus on selected weed hosts, artificial diet and cotton in the laboratory

Laboratory studies were conducted to obtain basic biological information of Lygus hesperus Knight (Hemiptera: Miridae) on alfalfa (Medicago sativa L.), pigweed (Amaranthus palmeri S. Wats.), Russian thistle (Salsola iberica Sennen and Pau), green bean (Phaseolus vulgaris L.), artificial diet, and cotton (Gossypium hirsutum L.) square and cotton boll at 27 degrees C. The nymphal developmental duration was 28.8 d on cotton bolls, nearly twice longer, compared with approximately 15 d in other hosts. The nymphal survivorship was significantly lowest on the cotton boll (18%), whereas the survivorship in other hosts ranged from 33% (cotton square) to 93% (green bean). The average total nymphal survivorship was approximately 60% and the most nymphal mortalities occurred on the first three instars. The life-table parameters were obtained only in cotton square, artificial diet, green bean, and alfalfa. The average adult longevity in artificial diet was the shortest (18.7 d),with the longest longevity observed (36.1 d) on green beans. The intrinsic rates of population increase (r(m)) were much higher in artificial diet (0.0771) and green beans (0.0671) than in alfalfa (0.0327) and cotton square (0.0317). Although statistically significant, the difference in r(m) values between alfalfa and cotton square was very small, indicating the similarity in reproductive suitability of cotton square and alfalfain a no-choice test. Thus, even though cotton is not a preferred host, when blooming alfalfa and roadside weeds are mowed in the Texas High Plains during June-July, it is the most likely time that Lygus bugs may move from alfalfa and other host plants into adjacent cotton fields and become effective pest of actively fruiting cotton.