Jeffrey P. Shapiro

Research toward an Artificial Diet for Adult Asian Citrus Psyllid

ABSTRACT n Research progress is reported on an artificial diet for adult Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). The primary objective was to develop a system for screening antimicrobial peptides and other potential toxic proteins for activity against adults. The base diet was a sterilized solution of sucrose (30%) and yellow-green food coloring (0.5%) in tap water. All of the studies presented were conducted at 25°C, 75% RH, and a photoperiod of 14:10 (L:D) h. Adult psyllids were <7 d old when they were transferred to diet. Addition of the food coloring was necessary to prompt adults to feed. Among the feeding trials discussed, a mean of 69.1 ± 3.2% adults survived for 14 d on the base sucrose diet. Survival rates of males and females were similar. Adults feeding on the sucrose diet may have ingested less food than adults feeding on citrus leaf disks based on differences in quantities of adult excrements deposited in feeding chambers. However, survival of adults feeding on leaf disks over a 2-wk period was only marginally better than survival of adults feeding on the base sucrose diet, and final rates of survival of adults fed these two food sources were not significantly different.

Vitellin and vitellogenin in the soldier bug, Podisus maculiventris: Identification with monoclonal antibodies and reproductive response to diet†

A 171,000 M(r )polypeptide of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) that constituted 16% of the protein in eggs also constituted up to 25% of the protein in hemolymph of fed females. It was identified as the major or sole apoprotein of vitellogenin. Eggs contained major polypeptides of 171, 106, and 51 kDa. The hemolymph polypeptide was identified with a polypeptide (vitellin) in egg extracts by comparing molecular weights, specificity of occurrence in fed females, and immunological reactivities. Females, starved for 5 days after eclosion to assure complete previtellogenic development, produced vitellogenin within a day after feeding on larval Galleria mellonella, and within 4 days after feeding on an artificial diet. Appearance of vitellogenin preceded ovarian growth by 2-3 days. Two monoclonal antibodies raised against egg proteins of P. maculiventris were selected for their strong reaction against egg extract and female hemolymph and null reaction against male hemolymph. Only one 170-kDa band in egg and hemolymph reacted with the antibodies on denaturing Western blots. These monoclonal antibodies are being used to develop an enzyme-linked immunosorbent assay (ELISA) to quantitate reproductive response of females to diets of differing quality.

Oviposition and Isolation of Viable Eggs from Orius insidiosus in a Parafilm and Water Substrate: Comparison with Green Beans and Use in Enzyme-Linked Immunosorbent Assay

Abstract Plant parts are commonly used as oviposition substrates for mass rearing of Orius spp., but this system does not permit the isolation of clean intact eggs for use as standards in a yolk protein enzyme-linked immunosorbent assay (ELISA). An oviposition substrate was devised for O. insidiosus by forming water-filled domes from Parafilm-M. Eggs were deposited through the Parafilm skin into water where they remained viable for at least 24 h. Eggs were extracted from the domes and collected onto black filter paper and then used to prepare lyophilized yolk protein as a quantitative standard in ELISA tests. In no-choice tests, O. insidiosus females oviposited 5.86 eggs per female per d into ‘Blue Lake’ green beans, Phaseolus vulgaris L., and 3.06 eggs into water-filled domes. Hatch rates did not significantly differ, although optimal moisture was critical. In a choice test, O. insidiosus females preferred beans to domes (4.02 versus 0.03 eggs per female per 18 h). Females preferred to oviposit into the walls of the major groove of green beans and often oviposited around the lower perimeter of water-filled domes. Lyophilized protein from eggs collected in water-filled domes was successfully and replicably used in the yolk protein ELISA after compensating for reduced immunological activity with a correction factor. Parafilm-covered water-filled domes are therefore useful for collection of eggs for use in the yolk protein ELISA and for other applications that require viable eggs. These domes also may lead to discovery of the phytochemical and physical factors that are responsible for choice of a host plant and its parts for oviposition.

Growth of a pupal ectoparasitoid, Diapetimorpha introita, on an artificial diet: stimulation of growth rate by a lipid extract from host pupae

An artificial diet used to rear the ectoparasitoid,Diapetimorpha introita, was supplemented withlipids extracted from pupae of the host, Spodoptera frugiperda (J. E. Smith). The diet alsowas sequentially supplemented with four fatty acids(arachidonic, linoleic, γ-linolenic and oleic),flax oil and Lipid Concentrate® which is used in cellculture. Pupae were homogenized and extracted withchloroform:methanol (2:1 v/v) and after drying downthe chloroform and methanol phases separately, theresidues from each solvent phase were evaluated in theartificial diet. Growth-promoting activity wasobserved in the chloroform phase containing lipids. Diet supplemented with lipid stored at −80 °C, andinsects reared on diet with fresh 1× and 2× extractsdeveloped significantly faster than those reared onthe artificial diet but slower than those reared onhost pupae. The fresh 1× and the 2× extracts alsoenhanced the average weight of the males and females,respectively. Storing the lipids at −20 °C resultedin a loss of activity. A lipid extract from Galleria mellonella pupae increased the averageweight of male and females but did not increase theirdevelopmental rate. Adult emergence was not improvedby any of the dietary additives. None of thecommercial lipid treatments significantly reduceddevelopmental time; however, the γ-linolenicacid-supplemented diet significantly increased theaverage weight of females. TLC analyses of the lipidextract from S. frugiperda revealed lipidsrepresenting four classes of neutral lipids in theextract: triolein, cholesterol, diacylglycerol, andphospholipid. Data from this study indicate thatoptimization and successful utilization of anartificial diet to rear D. introita depends onidentification of host factors required by theparasitic for growth and development.

Mi-1.2, an R gene for aphid resistance in tomato, has direct negative effects on a zoophytophagous biocontrol agent, Orius insidiosus

Summary This paper reports that even specific targeted forms of pest resistance in plants can have non-target effects, and may not always be compatible with biological control for integrated pest management.

Biotype-specific expression of dsRNA in the sweetpotato whitefly

This study was conducted to evaluate the effect of two different biotypes of the sweetpotato whitefly, Bemisia tabaci (Gennadius), on the induction of squash silverleaf (SSL), and to determine if double‐stranded RNA (dsRNA) occurs in geographically remote populations of the two biotypes. Recently collected B‐biotype whiteflies from Florida, Arizona, Mississippi, and Texas (SPW‐B) all contained a 7.0 kb dsRNA molecule. Kb dsRNA molecule. Laboratory colonies of A‐biotype whiteflies that were originally collected in 1981 from cotton in Arizona and California did not contain the 7.0 Kb dsRNA. When the two biotypes were compared only the SPW‐B induced rapid onset, grade 5, SSL. DsRNA similar to that found in adult SPW‐B was concentrated in whitefly nymphs, but host plant leaf tissue did not contain any consistent dsRNA molecules. SPW‐A only induced low‐grade SSL and progeny of SPW‐A that were fed on pumpkin plants displaying SSL did not acquire the ability to express dsRNA or induce SSL. Our data suggest that dsRNA is not directly involved in the induction of SSL and that SSL is a host‐specific response to a feeding injury induced by B‐biotype whiteflies. The origin and source of the 7.0 Kb dsRNA molecule remains enigmatic but its expression is constant in the whitefly biotype that is responsible for the induction of SSL and several other plant disorders in the U.S.