Nutrition of the Tobacco Budworm: an Economical Larval Diet for Rearing
TL;DR: A new soy flour-grain oil formulation was more efficient and economical than the standard (soybean-wheat germ) larval diet used to rear Heliothis virescens (F).
Abstract: A new soy flour-grain oil formulation was more efficient and economical than the standard (soybean-wheat germ) larval diet used to rear Heliothis virescens (F.). Weights of larvae and pupae, percent pupation and adult eclosion, number matings per male, and number of eupyrene sperm per single mating were greater in insects reared on the soy flour-grain oil diet. The approximate costs of the standard (high agar) diet for rearing insects in cups or the modified standard (low agar) diet for mass-rearing in tray units are $0.47 and $0.30/liter, respectively.
The cost of one liter of the new (low agar) formulation, in which wheat germ is replaced by grain oils, is $0.17 (with wheat germ oil) or $0.14 (with corn oil). The new diet also can be used successfully with both types of rearing container. The use of this diet in our laboratory would produce a savings of ca. $10,000/year.
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TL;DR: It is suggested that physiological constraints limit the defense combinations of any one species to a restricted subset of those observed, as species with the escape syndrome suffer much higher rates of damage.
297 citations
TL;DR: It is evident from results that modifications to the protein content and the nutrient composition profile of the original wheat germ-based insect artificial formula can be used to produce subtle negative effects on the growth of tobacco budworm.
Abstract: Soybean flour and wheat germ are the two most important protein components of wheat germ-based insect artificial diets. The effect of modifying the proportion of these two ingredients in a Noctuidae-specific diet was investigated utilizing the tobacco budworm Heliothis virescens (F.) (Lepidoptera: Noctuidae), with the goal of developing a suboptimal diet that, without drastically affecting this insect's growth and reproductive rates, could manifest subtle negative effects in this insect. The original diet formula contained 2.51% protein. When the proportions of soybean flour and wheat germ were changed to 2.15% protein the net reproductive rate of the first generation was significantly lower. In the second generation, the net reproductive rate, development time, percent female survivorship, fertility, intrinsic rate of increase, finite rate of increase and female longevity were significantly lower in both the 2.15% and 2.26% protein diets. The survival rate of immatures to the adult stage was 1% in the 2.05% protein diet in the first generation. Interestingly, females exposed to these suboptimal diets produced a significantly higher number of eggs but the survival of their larvae was significantly reduced. It is evident from these results that modifications to the protein content and the nutrient composition profile of the original wheat germ-based insect artificial formula can be used to produce subtle negative effects on the growth of tobacco budworm.
50 citations
TL;DR: Life table parameters such as net reproductive rate, finite rate of increase, and generation time indicated that Trifolium repens, a wild host growing around agricultural fields year round, could be one of the most suitable local plant hosts for the development of H. virescens.
Abstract: Heliothis virescens F. is an important polyphagous pest that can develop on >100 plant species, including 20 economic crops. Populations of this insect are believed to be locally maintained on a few crops and weed hosts in Washington County, MS. To find the intrinsic value of these plants for the development of H. virescens populations, we fed different laboratory and wild colonies with fresh and lyophilized plant tissue under a constant temperature. Development time of this insect under laboratory conditions varied up to 10 d between plant hosts and was dependent on the type of plant tissue provided: fresh or lyophilized. Life table parameters such as net reproductive rate, finite rate of increase, and generation time indicated that Trifolium repens, a wild host growing around agricultural fields year round, could be one of the most suitable local plant hosts for the development of H. virescens. Two species of Geranium, previously reported as the source of the first H. virescens generation in the region, had lower intrinsic value as a food source than did T. repens. Gossyipium hirsutum, perhaps the most important crop source of H. virescens in the region, produced low net reproductive rate and finite rate of increase parameters. Sampling conducted in agricultural fields during 2006 and 2007 found no larvae on the above mentioned wild hosts as it was previously reported. Results indicated that H. virescens populations in this region were not supported by the wild plant species growing around agricultural fields during the time when the survey took place.
38 citations
TL;DR: There was no evidence for any of the fitness traits to suggest that the locally resident haplotype (Northwestern) performed relatively better on nightshade than the other two haplotypes, and mating between psyllids of different haplotypes affected sperm transfer and egg hatch rates.
Abstract: Potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a serious pest of solanaceous crops in North and Central America and New Zealand. This insect vectors the bacterium that causes zebra chip disease of potato (Solanum tuberosum L.). Four distinct genetic populations, or haplotypes, of B. cockerelli have been identified. Three of the haplotypes may co-occur in potato fields in the Pacific Northwest of United States. Solanaceous weeds, including the perennial Solanum dulcamara (bittersweet nightshade), may provide refuge for psyllid populations which then migrate to potato crops. This study tested whether fecundity, fertility (% egg hatch), and adult longevity of potato psyllid were affected by host plant (S. dulcamara or potato) and whether these reproductive traits were similar among the three haplotypes that are most common in the Pacfic Northwest: Northwestern, Central, and Western. We hypothesized that the locally resident haplotype (Northwestern), which is known to overwinter extensively on S. dulcamara, would show relatively higher fitness on nightshade than the other two haplotypes. Fecundity differed significantly among haplotypes, with an average lifetime fecundity of 1050, 877, and 629 eggs for Northwestern, Western, and Central females, respectively. Egg hatch was significantly reduced in psyllids reared on bittersweet nightshade (61.9%) versus potato (81.3%). Adult psyllids lived longer on nightshade than on potato, averaging 113.9 and 108.4 d on nightshade and 79.0 and 85.5 d on potato for males and females, respectively. However, the longer life span of psyllids on nightshade than potato failed to lead to higher fecundity, because females on nightshade often ended egglaying well before death, unlike those on potato. There was no evidence for any of the fitness traits to suggest that the locally resident haplotype (Northwestern) performed relatively better on nightshade than the other two haplotypes. Lastly, we examined whether mating between psyllids of different haplotypes affected sperm transfer and egg hatch rates. Females of the Northwestern haplotype failed to produce viable eggs when mated by males of either the Western or Central haplotypes.
14 citations
01 Jan 2014
TL;DR: Development time was longer for psyllids reared on nightshade than potato, and the duration of the pre-oviposition period, egg incubation requirements, nymphal development time, and total developmental time was higher on bittersweet nightshades than potato.
Abstract: By Tariq Mustafa, Ph.D. Washington State University December 2014 Chair: Richard S. Zack Zebra chip, a new and economically important disease of potato, is threatening potato production in the United States, Mexico, Central America, and New Zealand. The disease is associated with the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso), vectored by potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). This insect pest feeds on over 40 plant species, including cultivated and wild solanaceous plants. Recent discoveries of four genetic variants (haplotypes) of potato psyllid, coupled with the finding that it overwinters in the Pacific Northwest on bittersweet nightshade (Solanum dulcamara), may complicate management of this psyllid, if differences exist in biological traits among the haplotypes. The present study compared development and reproduction among three psyllid haplotypes (Central, Western, and Northwestern) commonly found on Pacific Northwest potato crops, when reared on potato or bittersweet nightshade. Lso transmission efficiency among the three haplotypes was also assessed. The results showed that development time was longer for psyllids reared on nightshade than potato. The duration of the pre-oviposition period, egg incubation requirements, nymphal development time, and total developmental time was higher on bittersweet nightshade compared
3 citations