Effect of inorganic and organic forms of selenium supplementation on development of larval Heliothis virescens

Abstract

Selenium (Se) is an essential micronutrient for vertebrates though little is known about the effects on insects. Herbivorous insect larvae acquire Se from plant tissues in the inorganic form of sodium selenate and sodium selenite, and in the organic form of selenoamino acids, selenomethionine, and selenocystine. In this study, we document the effects of dietary supplementation with sodium selenite, sodium selenate, selenocystine, selenomethionine, and selenized yeast on the developmental rate of Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae). Larvae tolerated high levels of Se (500 μ g g -1 Se) as sodium selenate and to a lesser extent as selenocystine. Lower levels of sodium selenite (>1 μ g g -1 Se) caused increased mortality, reduced rates of pupation, more pupal/adult intermediates, and reduced adult emergence. Selenomethionine proved toxic to larvae at levels above 25 μ g g -1 Se, significantly delaying pupation and raising mortality. Provision of Se as selenized yeast, which contains primarily selenomethionine, was also extremely detrimental to larval development and survival. The results indicate that the impact of dietary Se supplement for insects may differ from vertebrates.

Effects of selenium on development, survival, and accumulation in the honeybee (Apis mellifera L.)

“…All 4 forms of Se had developmental consequences for A. mellifera larvae reared in vitro. Ephydra cinerea Jones (Diptera: Ephydridae) [41], Cotesia marginiventris (Cresson; Hymenoptera: Braconidae) [1], Heliothis virescens (Fabricius; Lepidoptera: Noctuidae) [42], M. scalaris [25], Podisus maculiventris Say (Hemiptera: Pentatomidae) [43], and S. exigua [21] also experienced similar sublethal effects when fed Se, including extended development times. In the present study, all 4 Se forms reduced the percentage of larvae reaching the prepupal stage.…”

Analysis of ESTs generated from immune-stimulated hemocytes of larval Heliothis virescens

“…Because we had previously documented a dietary requirement for the micronutrient selenium in resistance to baculovirus infection in T. ni and in H. virescens larvae (Popham et al, 2005;Shelby and Popham, 2007;Popham and Shelby, 2007) we expected to identify candidate selenoproteins linked to this phenomenon for further study. Hemocyte RNA from selenium supplemented H. virescens larvae was included in the pool of RNA used to construct the cDNA library in an attempt to capture selenium-induced transcripts.…”

“…from 4th instar larvae in order to minimize the sampling of HzSNPV transcripts. Additionally, a group of larvae were reared on the basal BioServ diet supplemented with 10 ppm sodium selenite as this micronutrient is known to boost resistance against baculovirus infection (Popham et al, 2005;Popham and Shelby, 2007). Hemocytes were collected from early 4th instar larvae exposed to sodium selenite.…”

Selenium Toxicity to Honey Bee (Apis mellifera L.) Pollinators: Effects on Behaviors and Survival

“…Selenomethionine was toxic only at the highest dosage. In other insect plant-feeders, selenomethionine was as toxic as selenate in S. exigua [33], but more toxic than selenate in H. virescens [60]. In the detritivore Megaselia scalaris Loew (Diptera: Phoridae), selenomethionine was more toxic than selenate [47].…”