Advances in genetics have made it feasible to genetically engineerinsect strains carrying a conditional lethal trait on multiple loci. Wemodel the release into a target pest population of insects carrying adominant and fully penetrant conditional lethal trait on 1–20 loci.Delaying the lethality for several generations after release allows thetrait to become widely spread in the target population before beingactivated. To determine effectiveness and optimal strategies for suchreleases, we vary release size, number of generations until theconditional lethality, nonconditional fitness cost resulting from geneinsertions, and fitness reduction associated with laboratory rearing.We show that conditional lethal releases are potentially orders ofmagnitude more effective than sterile male releases of equal size, andthat far smaller release sizes may be required for this approach thannecessary with sterile males. For example, a release of male insectscarrying a conditional lethal allele that is activated in theF₄ generation on 10 loci reduces the target population to10⁻⁴ of no-release size if there are initially tworeleased males for every wild male. We show how the effectiveness ofconditional lethal releases decreases as the nonconditional fitnessreduction (i.e., fitness reduction before the trait becomes lethal)associated with the conditional lethal genes increases. For example, ifthere is a 5% nonconditional fitness cost per conditional lethalallele, then a 2:1 (released male:wild male) release with conditionallethal alleles that are activated in the F₄ generationreduces the population to 2–5% (depending on the degree of densitydependence) of the no-release size. If there is a per-allele reductionin fitness, then as the number of loci is increased there is atrade-off between the fraction of offspring carrying at least oneconditional lethal allele and the fitness of the released insects. Wecalculate the optimal number of loci on which to insert the conditionallethal gene given various conditions. In addition, we show howlaboratory-rearing fitness costs, density-dependence, and all-maleversus male-female releases affect the efficiency of conditional lethalreleases.

With recent advances in genetics, many new strategies for pestcontrol have become feasible. This is the second article in which wemodel new techniques for pest control based on the mass release ofgenetically modified insects. In this article we model the release ofinsects carrying a dominant and redundant female killing or sterilizing(FK) allele on multiple genetic loci. If such insects are released intoa target population, the FK allele can become widely spread in thepopulation through the males while reducing the population eachgeneration by killing females. We allow the number of loci used to varyfrom 1 to 20. We also allow the FK allele to carry a fitness cost inmales due to the gene insertions. Using a model, we explore theeffectiveness and optimal strategies for such releases. In the mostideal circumstances (no density-dependence and released insects equalin fitness to wild ones), FK releases are several orders of magnitudemore effective than equal sized sterile male releases. For example, asingle release of 19 FK-bearing males for every two wild males, withthe released males carrying the FK allele on 10 loci, reduces thetarget population to 0.002% of no-release size. An equal sized sterilerelease reduces the target population to 5% of no-release size. Wealso show how the effectiveness of the technique decreases as thefitness cost of the FK alleles in males increases. For example, theabove mentioned release reduces the target population to 0.7% ofno-release size if each FK allele carries a fitness cost in males of5%. Adding a simple model for density-dependence and assuming thateach of the released males carries the FK allele on six loci, we showthat the release size necessary to reduce the target population to1/100 of no-release size in 10 generations of releases varies from0.44:1 to 4:1 (depending on parameter values). We also calculate theoptimal number of loci on which to put the FK allele under variouscircumstances.

A prominent hypothesis about insecticide resistance is that genesof major effect play a key role in field-evolved resistance because theintensity of selection is extremely high in the field. A corollaryhypothesis is that the lower intensity of selection in laboratoryselection experiments favors polygenic control of insecticideresistance. Contrary to these hypotheses, a literature review revealedthat the intensity of selection for insecticide resistance in the fieldvaries widely and overlaps broadly with selection intensities in thelaboratory. Also contrary to these hypotheses, results from simulationsof population genetic models suggest that selection intensities typicalof laboratory selection experiments favor resistance that is conferredby major genes. Major genes dominated responses to selection forresistance across a wide range of simulated selection intensities, withand without fitness costs and refuges. The simulation results alsosuggest that the intensity of selection, rather than the number of lociconferring resistance, is central in determining rates of resistanceevolution and effectiveness of refuges.

Dominance has been assessed in different ways in insecticideresistance studies, based on three phenotypic traits: the insecticideconcentration required to give a particular mortality(D_LC), mortality at a particular insecticidedose (D_ML), and fitness in treated areas(D_WT). We propose a general formula forestimating dominance on a scale of 0 to 1 (0 = completerecessivity and 1 = complete dominance).D_LC, D_ML, andD_WT are not directly related and their valuesdepend on genetic background and environmental conditions. We also showthat pest management strategies can have the consequence to increaseD_WT via the selection of dominance modifiers.Studies on resistance to Bacillus thuringiensis toxinsprovide the ultimate example of the complexity of the definition of theconcept of dominance. Almost all studies have focused on calculation ofD_LC, which provides little information about theefficiency of pest management programs. For instance, one assumption ofthe high dose/refuge strategy is that Bacillus thuringiensisresistance must be effectively recessive (i.e.,D_ML must be close to zero). However,D_WT, rather than D_ML, isrelevant to the resistance management strategy. Therefore, we stronglysuggest that the time has come to focus on fitness dominance levels inthe presence and absence of insecticide.

The proportion of Varroa jacobsoni Oudemans that werealive and mobile when they fell from honey bees, Apismellifera L., in hives was measured during a 20-wk period todetermine the potential use of systems that prevent these mites fromreturning to the bees. Traps designed to discriminate between the live,fallen mites and those that are dead or immobile were used on hivebottom boards. A large fraction of the fallen mites was alive whenacaricide was not in use and also when fluvalinate or coumaphostreatments were in the hives. The live proportion of mitefall increasedduring very hot weather. The proportion of mitefall that was alive washigher at the rear and sides of the hive compared with that fallingfrom center frames near the hive entrance. More sclerotized than callowmites were alive when they fell. A screen-covered trap that covers theentire hive bottom board requires a sticky barrier to retain all livemites. This trap or another method that prevents fallen, viable mitesfrom returning to the hive is recommended as a part of an integratedcontrol program. It also may slow the development of acaricideresistance in V. jacobsoni and allow the substitution ofless hazardous chemicals for the acaricides currently in use.

The tendency of honey bees, Apis mellifera L, to becomeinfested with tracheal mites, Acarapis woodi (Rennie), wasmeasured in six different types of F₁ colonies. Thecolonies were produced by mating a stock (Buckfast) known to resistmite infestation to each of five commercially available stocks and to astock known to be susceptible to mites. Young uninfested bees fromprogeny and parent colonies were simultaneously exposed to mites ininfested colonies, then retrieved and dissected to determine resultantmite infestations. Reduced infestations similar to but numericallygreater than those of the resistant parent bees occurred in each of thesix crosses made with resistant bees regardless of the relativesusceptibility of the other parental stock. Reciprocal crosses betweenresistant and susceptible queens and drones proved equally effective inimproving resistance. Therefore, allowing resistant stock queens tomate naturally with unselected drones, or nonresistant queens to matewith drones produced by pure or outcrossed resistant queens, can beused for improving resistance of production queens.

Nine different genetic families of honey bees (Apismellifera L.) were compared using summed z-scores (phenotypicvalues) and a modified selection index (I_mod).I_mod values incorporated both the phenotypic scores of thedifferent traits and the economic weightings of these traits, asdetermined by a survey of commercial Ontario beekeepers. Largelybecause of the high weight all beekeepers place on honey production, adistinct difference between line rankings based on phenotypic scoresand I_mod scores was apparent, thereby emphasizing the needto properly weight the traits being evaluated to select bee stocks mostvaluable for beekeepers. Furthermore, when beekeepers who made >10%of their income from queen and nucleus colony sales assigned relativevalues to the traits used in the I_mod calculations, theresults differed from those based on weightings assigned by honeyproducers. Our results underscore the difficulties the North Americanbeekeeping industry must overcome to devise effective methods ofevaluating colonies for breeding purposes.

Nineteen compounds were evaluated in combination with a solution ofacetic acid as baits for trapping the German yellowjacket,Vespula germanica (F.), the western yellowjacketVespula pensylvanica (Saussure), and the golden paper waspPolistes aurifer Saussure. Compounds with three to sixcarbon chains or branched chains and with a hydroxy functional groupwere selected for testing based on their similarity to isobutanol. Theywere compared with isobutanol with acetic acid, which is a known waspattractant. None of the compounds tested were superior to isobutanolwhen presented with acetic acid as a lure for these species of wasps.However, traps baited with either the S-(−)- or the racemic mixture of2-methyl-1-butanol in combination with acetic acid captured similarnumbers of both species of yellowjackets, compared with isobutanol withacetic acid. Polistes aurifer responded strongly to theS-(−)-enantiomer and to the racemic mixture of 2-methyl-1-butanol withacetic acid and not to the R-( )-enantiomer with acetic acid.

A study was undertaken to isolate entomopathogens of southwesterncorn borer, Diatraea grandiosella Dyer, and southern cornstalk borer, Diatraea crambidoides (Grote). Field-collecteddiapausing larvae of southwestern corn borer (three sites inMississippi) and southern corn stalk borer (one site in NorthCarolina), and a laboratory strain of D. grandiosella in thediapause state were maintained in a simulated winter followed by asimulated spring environment. Few larvae (≤6%) collected from any ofthe field sites died in the winter environment, and most insectmortality (11–25%) occurred after transfer of the larvae to thesimulated spring environment. Mortality during the simulated springperiod differed among the collection sites, and the highest mortalitywas recorded for southwestern corn borers from Washington County(25%), followed by Marshall (16%) and Oktibbeha (11%) Counties. Ahigh level of mortality was also observed in southern corn stalk borersduring the simulated spring period (27%). No viruses were observed,but a number of bacteria, microsporidia, and fungi were isolated fromboth southwestern corn borer and southern corn stalk borer larvae andpupae. In most instances, numerous bacterial taxa were isolated fromcadavers, but on some occasions a single taxon predominated. The mostprevalent bacterial taxon from larval and pupal cadavers wasEnterococcus faecalis (Andrewes & Horder) Schleifer &Kilpper-Balz, but Bacillus spp., Pseudomonasaeruginosa (Schroeter) Migula, and Serratia marcescensBizio were frequently isolated as well. Few fungi (1–7%) wererecovered from southwestern corn borer and southern corn stalk borerlarvae and pupae. The most common entomopathogenic taxon isolated wasBeauveria bassiana (Balsamo) Vuillemin from southern cornstalk borer larvae. Microsporidia were not isolated from southern cornstalk borers. However, Nosema spp. were isolated fromsouthwestern corn borer cadavers from Washington (15%), Marshall(1%), and Oktibbeha (3%) Counties in Mississippi. In addition, weobserved parasitism of southern corn stalk borer larvae byMacrocentrus cingulum Reinhard (Hymenoptera: Braconidae). Noparasitism of southwestern corn borers was observed. Isolates ofBacillus, Beauveria, Entercoccus,Nosema, Pseudomonas and Serratia wereall pathogenic to southwestern corn borer larvae under controlledenvironmental conditions, and with the exception of B.bassiana, these are novel pathogens of Diatraea cornborers.

Development, fecundity, and longevity of Colpoclypeusflorus (Walker), a parasitoid of Adoxophyes orana(Fischer von Röslerstamm) (Lepidoptera: Tortricidae), werestudied under laboratory conditions at different constant temperatures.Developmental time from egg to adult was inversely related totemperature and at 25°C was 12.81 ± 0.19 d. No adultsemerged at 30°C. The thermal units required for development from eggto adult were 232.56 ± 19.5 degree-days. Female C.florus oviposited (mean ± SEM) on average 30.7, 57.4, 46.6,and 34.1 eggs at 15, 17, 20, and 25°C, respectively. Adult longevitywas 11 ± 1.25 d at 17, whereas it decreased to 4.5 ±0.4 at 25°C. Honey significantly increased longevity for both malesand females. The highest net reproductive rate was 30.739 at 17°C,whereas the highest intrinsic rate of increase and the shortestdoubling time occurred at 25°C.

Two granulosis viruses (GV) were tested as enhancers for the gypsymoth nuclear polyhedrosis virus (LdMNPV). Helicoverpaarmigera (Hübner) GV (HaGV) had no detrimental effect uponlarval growth and development, but in combination with LdMNPV itreduced both the LC₅₀ and the LT₅₀ for the NPV.In addition, the combination also adversely affected the growth anddevelopment of gypsy moth larvae. The LC₅₀ of LdMNPV wasreduced by as much as 300-fold (HaGV at 10⁻² dilution) andthe LT₅₀ was reduced by as much as 18% (HaGV at10⁻² dilution). Spodoptera frugiperda (J.E. Smith) GV reduced the LC₅₀ of LdMNPV by as much as13-fold but had no effect upon the LT₅₀.

We evaluated the toxicity of three insecticides (lambdacyhalothrin, spinosad, and S-1812) to the natural enemies Braconmellitor Say, Cardiochiles nigriceps Viereck,Coleomegilla maculata De Geer, Cotesiamarginiventris (Cresson), Geocoris punctipes (Say), andHippodamia convergens Guérin-Méneville, intopical, residual, and field assays. Lambda cyhalothrin exhibited thegreatest toxicity to the natural enemies. In topical toxicity tests,lambda cyhalothrin adversely affected each natural enemy speciesstudied. Residues of lambda cyhalothrin on cotton leaves were toxic toB. mellitor, C. nigriceps, C.maculata, and G. punctipes. Interestingly, residues ofthis insecticide were not very toxic to C. marginiventrisand H. convergens. Geocoris punctipes and C.maculata numbers in the field generally were significantly lowerfor lambda cyhalothrin treatments than for the other four treatments,substantiating the previous tests. Although cotton aphids began toincrease over all treatments around the middle of the test period, thenumber of cotton aphids in the lambda cyhalothrin plots wassignificantly higher than the number in any of the other treatments. Ascotton aphids increased in lambda cyhalothrin field plots, the predatorH. convergens also increased in number, indicating thatlambda cyhalothrin did not adversely affect it in accordance with theresidual tests. Spinosad exhibited marginal to excellent selectivity,but was highly toxic to each parasitoid species and G.punctipes in topical toxicity tests and to B. mellitorin residual tests. Spinosad generally did not affect the number ofG. punctipes, H. convergens, and C. maculata inthe field except for one day after the second application for G.punctipes. S-1812 exhibited good to excellent selectivity to thenatural enemies. Some reduction of G. punctipes occurred foronly a short period after the first and second application of thisinsecticide in the field. H. convergens and C.maculata were affected very little by S-1812.

Lythrum salicaria L., purple loosestrife, an invasiveEurasian perennial, is degrading wetlands across temperate NorthAmerica. Chemical, physical, and mechanical methods failed to providelong-term control. Therefore, four host-specific insect species (twoleaf feeders, a root feeder, and a flower feeder) were introduced asbiological control agents. To increase the availability of adults ofthe root feeding weevil Hylobius transversovittatus Goezefor field releases, we developed a semiartificial diet. Suitability ofdifferent diet formulations (varying vitamin mixes, salt mixes,antimicrobials, water content, root content) and temperatures forlarval development were evaluated. We also monitored how rearing onartificial diet and the number of larvae per container affected larvaldevelopment time, larval survival, adult weight, and incidences ofdeformities. Rearing larvae on artificial diet reduced development timefrom 1–2 yr to 2–3 mo. Larval development was fastest and survivalrates highest under constant temperatures of 25°C. Hatch rate andlarval survival decreased if eggs were surface sterilized. Using FABCOantimicrobials could not prevent fungal contamination; use of methylparaben and sorbic acid was successful in suppressing fungal andbacterial growth throughout larval development time to <10%. Themoisture content of the diet did not significantly affect larvalsurvival, development, or adult weight. Decreasing the proportion ofpurple loosestrife roots in the diet reduced adult weight and theproportion of larvae completing development, and increased developmenttime; no larvae were able to complete development in root-free diet.With an increase in the number of larvae per cup, survival rates werereduced. The experiments revealed a female biased sex ratio: femalesconsistently developed faster and were heavier than males. Incidence ofadult deformities was consistently below 5%. Increased availability ofadults for field release as a result of mass production using thesemiartificial diet will accelerate the biocontrol program targetingpurple loosestrife. We are able to produce several hundred weevils perweek and have adapted the diet to rear other root-feeding weevils.

Bacillus thuringiensis, isolate 114A, was used intoxicity experiments against the wild population of the olive pestBactrocera oleae (Gmelin). In laboratory experiments, sporesand crystals of the B.t. were delivered to the insects withthe food. Longevity, oviposition period, number of eggs produced, andpercent hatch were recorded. Olive fruits from the oviposition testwere dipped into a suspension containing spores and crystals ofB. thuringiensis 114A after the eggs were deposited. Infield experiments, four to six sprayings per year of B.t.114A isolate were applied for three successive years. It was foundthat, in addition to the longevity of B. oleae, theoviposition period, number of eggs and percent egg hatch decreased.Also, the percentage of pupation and emergence was reduced when olivefruits with eggs in their mesocarp were dipped in the solution ofspores and crystals. Field applications with the toxins of 114A isolateof B. thuringiensis have resulted in significant protectionof the olive production.

Studies were conducted to determine the utility of overseedingendophyte enhanced varieties of perennial ryegrass, Loliumperenne L., into existing stands of Kentucky bluegrass, Poapratensis L., to manage bluegrass billbug, Sphenophorusparvulus Gyllenhal, larval populations and their damage. Twocommercial varieties of endophyte enhanced perennial ryegrass (RepellII and Triple Play) were overseeded at two different rates in thefield. S. parvulus larval populations, their damage, andturfgrass composition were monitored over the course of 3 yr.Significantly fewer larvae were found in plots overseeded with RepellII, whereas Triple Play had no significant effect on larval populationdensity. Endophyte infection was confirmed in ≈58% of all Repell IIshoots, whereas only ≈31% of Triple Play shoots were infected.Regression analysis, using a segmented model, demonstrated that larvalpopulations declined as the proportion of endophyte-infected perennialryegrass increased. However, no additional reductions in larvalpopulation density were achieved in stands containing >40%endophyte-infected perennial ryegrass. Visual damage varied withcultivar, seeding rate, and year, but generally decreased as theproportion of endophyte-infected perennial ryegrass increased. Althoughseeding rate had an initial effect on turfgrass composition, thesedifferences were not detected after the first year of the study.Results indicate overseeding existing stands of Kentucky bluegrass withendophytic varieties of perennial ryegrass can reduce S.parvulus larval populations and their damage. However, plantgenetic characteristics (i.e., different cultivars) may be overridingdeterminants of many aspects of plant performance includingestablishment, tolerance to insect feeding, and expression ofendophyte-mediated resistance.

In 1995, ears of a experimental inbred (CG59-2) containing asynthetic Bacillus thuringiensis Cry IA(b) gene driven byPEPC, pith and pollen promoters and artificially infested withOstrinia nubilalis (Hübner) larvae in small plotstudies were free from insect damage, whereas 40–50% of thecorresponding non-Bt inbred ears were damaged. Bt inbred ears that wereinoculated with Aspergillus flavus Link and Fusariumproliferatum T. Matsushima (Nirenberg) or exposed to natural moldinoculum after infestation with O. nubilalis were free ofvisible signs of mold, as compared with ≈30–40% of the non-Bt earssimilarly treated. Results in 1996 using the same inbred with a singleallele dose of the Bt gene showed similar trends. Mean total fumonisinlevels for non-Bt versus Bt inbred ears were not significantlydifferent (2.8 versus 0.8 ppm, respectively) in 1996. In paired hybridstudies run in 0.4-ha (1-acre) fields, an event 176 Bt hybrid hadsignificantly lower amounts of damage and signs of Fusariumspp. mold, but not fumonisin, compared with a corresponding non-Bthybrid from 1996 to 1998. However, two hybrid pairs that containedeither MON810 or Bt11 constructs examined in similar fields at the samesite had lower levels of fumonisin in both 1997 (30- to 40-fold) and1998. High intrafield variability in insect infestation and presence ofHelicoverpa zea (Boddie) in Bt hybrids was apparentlyresponsible for fewer significant differences in fumonisin levels in1998. Similar trends for all three hybrid pairs were noted in smallplot trials at another site. Incidence of other ear pests or insectpredators varied as much among non-Bt hybrids as they did for Bt/non-Bthybrid pairs.

This research characterizes the interaction between the fire antsSolenopsis invicta Buren and developing soybean plants.Phagostimulant studies showed that fire ant foraging on soybean seedsincreased once the seeds imbibed water. During seedling developmentover a 5-d germination period, fire ant foraging shifted from thestem/cotyledons to the roots, despite continual increases in freshweights for each region, and the fact that stem/cotyledon tissuecontained the majority of food reserves. Carbohydrate analysis showedthat although 2-d-old seedlings had higher concentrations ofphagostimulant carbohydrates, especially sucrose, than tissues ofmature plants, all tissues analyzed had enough of these sugars toinduce a phagostimulant response. Fire ant association withseeds/seedlings germinated in soil resulted in reduced seedling vigor,as determined by a doubling of seedling emergence time, a threefoldincrease in malformed seedlings, and visible damage to cotyledons.Seeds germinated and grown to mature plants in association with fireants, allocated 43% more assimilate into pods, but produced 28% lessroot dry matter, 11% less total dry matter, and there was an 81%reduction in the number of root nodules compared with control plants.We propose that reduced root development and inhibitions of noduleformation would be major yield limiting factors under field conditions.This work demonstrates that fire ant damage to soybeans is not limitedto seedling establishment and that more research should be directed atthe subterranean activities of the fire ant.

A 3-yr project was initiated in 1993 to examine the effects ofinsecticides and sustained whitefly, Bemisia argentifoliiBellows & Perring [aka. B. tabaci Gennadius (Strain B)],feeding on alfalfa plant growth and vigor in greenhouse cage studies,and to determine the impact of natural Bemisia whiteflypopulations on alfalfa forage yields and quality in a large-plot fieldexperiment. Alfalfa plant growth and vigor after exposure toimidacloprid and a mixture of fenpropathrin and acephate insecticidesdid not differ from untreated plants in the greenhouse. Consequently,foliar and soil applied insecticides were used to manipulate whiteflydensities on alfalfa plants to measure whitefly feeding effects onplant growth and forage yield. Heavy whitefly densities on untreatedalfalfa plants in the greenhouse resulted in significant reductions inrelative growth rates and net assimilation rates as compared withimidacloprid-treated plants that were maintained relativelywhitefly-free. Reductions in alfalfa plant growth measured betweeninfested and treated plants were proportional to whitefly densities.Field plot results derived from three crop seasons were relativelyconsistent with our greenhouse trials. Both experimental approachesclearly showed that alfalfa plants exposed to high densities ofwhitefly immatures and adults grew at a significantly slower rate andproduced less foliage. As a result of reduced growth rates, alfalfamaturity in the naturally infested plots was estimated to be ≈7–10 dbehind managed plots. Delays in maturity resulted in significantreductions in forage yields of 13–18% during August–Septemberharvests when whitefly populations reached peak abundance. Whiteflyfeeding stresses also effected hay quality through the reduction ofcrude protein content and contamination of foliage with honeydew andsooty mold. The status of the Bemisia whiteflies as aneconomic pest to alfalfa is clearly evident from these studies, but thedamage potential of whiteflies in the southwestern United Statesappears to be restricted to one or two harvest periods during thesummer coinciding with peak adult populations and their dispersal fromalternate host crops.

With Malaise traps, we monitored the flight of adult Plecoptera andTrichoptera following emergence from headwater streams in the FernowExperimental Forest, WV, during the second year after application ofdiflubenzuron. We placed five traps at various distances from eachstream during May through September of 1991, 1992, and 1993. Wecollected pretreatment samples during the first year. In May 1992,diflubenzuron was applied to two watersheds, and the other twowatersheds were used as untreated references. The 1992 study tested theeffects of diflubenzuron that fell directly into the streams or werewashed into the stream during the first year. For 1993, we tested thehypothesis that diflubenzuron affected adult flight following emergenceduring the year following abscission and possible ingestion of thetreated leaves. The analysis compared the regressions of the number ofadults caught in each trap versus distance of the trap from the streamamong years and between treatments for each species. The flight of thestonefly Leuctra ferruginea (Walker) was reduced in thetreatment watersheds compared with the reference watersheds during theyear following abscission of the treated leaves. Adult flight of otherspecies did not decrease in the treatment watersheds during 1993. Theseresults show a relatively small effect of diflubenzuron on theseaquatic insects; however, our study involved only a single applicationof diflubenzuron. Additional research may be needed to predict thepossible effects of multiple applications of diflubenzuron over severalyears as often occurs during actual efforts to suppress gypsy moth,Lymantria dispar (L.).

Eucalyptus spp. plantations represent >60% of thereforested area in Brazil. Although ambrosia beetle attacks on livetrees were at first nonexistent, they have begun to appear with greaterfrequency. Monitoring for pest insects is a key factor in integratedpest management, and baited traps are one of the most widely usedmethods for insect population detection and survey. We compared theefficiency of the most widely used trap in Brazil to survey forambrosia beetles and other Scolytidae, the ESALQ-84 type, with othertraditionally employed traps: the multiple funnel (Lindgren trap);drainpipe; and slot (Theyson) traps, in a Eucalyptus grandisHill ex Maiden stand in Brazil. The ESALQ-84 trap was the mostefficient in trapping Hypothenemus eruditus Westwood andHypothenemus obscurus (F.); the multiple funnel trap caughtsignificantly more Cryptocarenus diadematus Eggers; whereasthe slot trap caught more Premnobius cavipennis Eichhoff andXyleborus affinis Eichhoff than the other traps. Thedrainpipe trap was the least effective trap overall. When corrected fornumber of beetles caught per trap surface area, catches weresignificantly higher on the ESALQ-84 trap for the majority of thespecies analyzed, probably because of a smaller trap surface area. Theslot trap was recommended for it caught overall more beetles of thethree most economically important scolytid species in eucalyptplantations in Brazil, P. cavipennis, X. affinis,and X. ferrugineus.

The Nantucket pine tip moth, Rhyaciona frustrana(Comstock), a common regeneration pest of loblolly pine, Pinustaeda L., has been shown to reduce tree volume yields throughlarval feeding. Chemical applications can be effective in protectingtrees from the growth losses associated with this feeding, and optimumspray timing values are commonly used to reduce the number of necessaryapplications and to increase insecticide efficacy. Optimal spray timingvalues for the Georgia Piedmont were obtained for the following fourinsecticides available for use in loblolly pine plantations: permethrin(Pounce), lambda-cyhalothrin (Warrior T), spinosad (SpinTor 2 SC), andBacillus thuringiensis variety kurstaki Berliner(Foray 48B). Optimal timing values were similar between the first andsecond generations for each of these compounds. All of the insecticidesused in this study significantly reduced tip moth damage below thecontrol treatment levels. Lambda-cyhalothrin was the most efficaciousand had the longest spray timing window. B. thuringiensiswas the least effective and had the shortest timing window. Spinosadand permethrin were similar in efficacy and spray timing values. Thisinformation is applicable to regions where there are three tip mothgenerations per year, as found in the southern Piedmont region and thecoastal plain of Virginia and most of North Carolina.

Bt and non-Bt sweet corn hybrids (Rogers ‘Empire’ Bt and non-Bt,respectively) were compared for distribution of kernel damaging insectpests in central Illinois in 1998 and 1999. The occurrence and damageby caterpillars [primarily Helicoverpa zea (Boddie)] werereduced by at least 80% in each year for the Bt compared with thenon-Bt hybrid. However, the incidence of sap beetle adults (primarilyCarpophilus lugubris Murray) was higher, and larvae, lowerfor the Bt versus non-Bt in 1999. The incidence of ears with more thanfive kernels damaged by sap beetles was higher for the Bt compared withnon-Bt hybrid in 1998 (13.8 versus 5.5%), but nearly equivalent in1999 (15.3 versus 15.1%, respectively). Distribution of predators onplants (primarily Coccinelidae) and harvested ears (primarilyOrius spp.) were not significantly different on Bt versusnon-Bt hybrids. Ears with husks flush with the ear tip or with ear tipsexposed had significantly higher sap beetle damage for both hybrids,and the Bt hybrids had significantly higher incidence of exposed eartips in both years. Sap beetle numbers determined by scouting wereoften proportional to numbers of beetles captured in baited traps,increasing and decreasing at about the same time. However, valuesdetermined with traps were typically less variable than when scouted,and time of sampling was typically four times more rapid for each trapthan for each 10 plant scout sample when measured in 1999.

The biology of the citrus psyllid Diaphorina citriKuwayama was studied at 25°C on four commonly grown citrus andrelated plants [rough lemon, Citrus jambhiri Lush; sourorange, C. aurantium L.; grapefruit, C. paradisiMacfadyen; and orange jessamine, Murraya paniculata (L.)Jack] in the laboratory. The biological characteristics of each lifestage are described. The average egg incubation periods on orangejessamine, grapefruit, rough lemon, and sour orange varied very little(4.1–4.2 d). The average nymphal developmental periods on these fourhost plants were essentially the same except the fifth stadium.Survival of immatures on orange jessamine, grapefruit, rough lemon, andsour orange was 75.4, 84.6, 78.3, and 68.6%, respectively. Femaleadults lived an average of 39.7, 39.7, 47.6, and 43.7 d on theserespective host plants. The average number of eggs laid per female ongrapefruit (858 eggs) was significantly more than those on other hosts(P < 0.05). The intrinsic rate of natural increase(r_m) for D. citri on grapefruit washighest. Jackknife estimates of r_m varied from0.188 on grapefruit to 0.162 on orange jessamine and rough lemon. Themean population generation time on these hosts ranged from 31.6 to34.1 d. The continuous flushes produced by orange jessamine couldplay an important role in maintaining high populations of this vectorwhen the new flushes are not available in the commercial citrus groves.

Inadequate bee pollination limits rabbiteye blueberry,Vaccinium ashei Reade, production in the some areas of thesoutheastern United States. Honey bees, Apis mellifera L.,are currently the only manageable pollinators available for pollinatingV. ashei. However, a new adaptable pollinator for rabbiteyeblueberry, Osmia ribifloris Cockerell, was successfullyreared and flown in captivity. The bee nested successfully in woodenshelters and conferred superior fruit set to 2-yr-old potted, rabbiteyeblueberry bushes. Pollination efficiency or the percentage of blueberryflowers to set fruit after being visited once by a female O.ribifloris was comparable to that of the female blueberry beeHabropoda laboriosa (F.) and worker honey bees.Interestingly, honey bees once thought to be inefficient pollinators ofrabbiteye blueberry were found to be very efficient, especially for‘Climax’ and ‘Premier’ flowers.

Low, medium and high densities of western flower thrips,Frankliniella occidentalis (Pergande), were established inthree greenhouses at the Greenhouse and Processing Crops ResearchCentre, Ontario, Canada, in 1996 and 1998 to develop economic injurylevels for thrips on greenhouse cucumber. Thrips densities weremonitored weekly using yellow sticky traps and flower counts. Fruit washarvested twice a week, graded for size, weighed, and rated for thripsdamage using three damage categories. Significant yield reduction wasdetected 4 wk after severe fruit damage was observed in the high andmedium thrips density treatments in 1996 and 7 wk in 1998. Percentageof severe damaged fruit (P_F3) has significant linearrelationships with the adult thrips density (x) that was sampled bysticky traps 1 wk before harvest (P_F3 = −0.2533 0.0828x) and that was sampled by flower counts 2 wk before harvest(P_F3 = − 0.2025 0.5490x). Based on theregression equations, economic injury levels, expressed as adult thripsper sticky trap per day or adult thrips per flower, were calculated forvarious combinations of control costs, yield potential and fruitprices. The economic injury levels for F. occidentalisranged from 20 to 50 adults per sticky trap per day or 3 to 7.5 perflower as determined under average greenhouse production conditions inOntario, Canada.

The effects of the chitin synthesis inhibitor lufenuron againstpotato tuber moth, Phthorimaea operculella (Zeller), eggswere determined by topically exposing different age groups of eggs(1–4 d old) to treated potato tubers (Solanum tuberosum L.)under laboratory conditions. Larval hatch from both treated (4 and12 g [AI]/100 liter) and untreated tubers was >95%, butmortality of first instars was high in treated tubers (>90%) comparedwith untreated tubers. Examination of the treated tubers showed thatmost of the larvae were unable to penetrate or cause any noticeabledamage to the potato tubers. However, the few first instars thatsurvived were able to penetrate the tubers and continue theirdevelopment to the pupal or adult stages. At 12 g (AI)/100 liter,adult emergence was <2% and most of the emerged adults hadmorphological deformities such as reduced wing size and they wereunable to free themselves from the pupal sacs. These data suggest thattopical application of lufenuron to eggs before larval hatch wouldreduce the amount of damage caused by potato tuber moth as part ofintegrated pest management program.

Male and female codling moth, Cydia pomonella (L.), weremonitored with passive interception traps (PI-traps) in apple orchardstreated with sex pheromone dispensers. The proportion of mated femalesrecaptured by PI-traps was significantly higher than the proportionreleased after the release of both sexes into a codling moth-infestedorchard. However, no significant difference occurred between theproportion of mated females recaptured and released when only femaleswere released into uninfested orchards. Replicated nine-tree appleplots situated either on the edge or in the center of pheromone-treatedapple orchards were monitored with PI-traps during first moth flight in1995 and during both flights in 1996. Moths caught on PI-traps werepredominately males. The first male moths were captured 7–10 d beforefemales during the first flight in both years. Initial capture ofvirgin and mated females on PI-traps coincided in 1995. Mated femaleswere captured 14 d after the first virgin females in 1996. Themean proportion of females that were mated ranged from 32 to 55%during the first flight and 85 to 92% during the second flight. Mothcatch and fruit injury were significantly higher in the edge versus thecenter plots. The numbers of total and female moths caught withPI-traps were significantly correlated with fruit injury for eachgeneration. The percentage of female moths caught on PI-traps that weremated was 32% lower and the mean oocyte load of all females was 42%higher in a pheromone-treated apple orchard than in the untreatedcrabapple grove monitored during May and June 1997.

The spatial dispersion of armored scale insects; greedy scale,Hemiberlesia rapax (Comstock); and latania scale,Hemiberlesia lataniae (Signoret), was investigated onkiwifruit, Actinidia deliciosa (A. Chevalier) C. F.Liang et A. R. Ferguson, leaves in New Zealand. A universaldescription for dispersion was determined using Taylor’s power law,which encompassed a wide range of different orchards, blocks, blocksizes, sampling times, scale control practices, regions and seasons.Scale density significantly altered dispersion, especially at the highdensities found on unsprayed kiwifruit. Most commercially managedkiwifruit blocks had low densities of <0.5 scale per leaf and had aslightly aggregated scale dispersion. Wilson and Room’s binomialmodel, which incorporates a clumping pattern as a function of density,gave a significant relationship between the proportion of infestedleaves and scale density. The optimal leaf sample sizes were estimatedfor predetermined levels of sampling reliability. Where populationestimates require a high degree of precision and enumerative samplingmethods are used, 2,500 leaves should be sampled when scale densitiesare near the current spray threshold of 4% infested leaves and 500leaves at 20% infested leaves. For management-decision sampling, wherea lower level of precision was acceptable, enumerative sampling wouldrequire that 400 leaves be sampled at 4%; or 85 leaves at 20%infested leaves. With binomial sampling to achieve an equivalent levelof precision an increased sample size of 6–11% is required.

The effectiveness of tebufenozide applied against the adult, egg,and larvae of codling moth, Cydia pomonella (L.), wasevaluated. Significant reductions in fecundity and egg hatch occurredafter 1-h and 24-h exposures of females and 24-h exposures ofmales-only to residues in plastic plates. A significant reduction inegg hatch was also found after a 1-h exposure of males. The ovicidaleffects of tebufenozide in field trials did not significantly differfor eggs laid on residues or treated topically. Corrected egg mortalityexceeded 95% for cohorts laid <130 degree-days after sprays wereapplied. Fecundity and egg hatch were measured after either a 24-hexposure of moths or a 10-d exposure of moths and eggs on apple trees.Significant reductions in both fecundity and fertility occurredcompared with an untreated control up to 7 d in the 24-h assaysand accounted for 60–70% fewer larvae produced per mated female. Themean numbers of larvae produced per mated female after the 10-dexposure were reduced 100–75% in assays started on day 0–21 afterthe spray application compared with the untreated control. Fecunditywas significantly reduced for 7 d and egg hatch was reduced forthe entire 21-d test period in these trials. Residues had a 14-dhalf-life on apple foliage. Residues applied to foliage or to foliageand fruit did not significantly increase the proportion of uninjuredfruit compared with the untreated control in bioassays where neonateswere placed on foliage 10 cm from fruit. However, the proportion ofinjured fruits with shallow stings versus deep entries was higher onthe treated versus the untreated plants. Field applications oftebufenozide reduced fruit injury >90% when applied early duringemergence. Plots treated after the beginning of egg hatch had a largerproportion of injured fruits with shallow larval feeding.

Cross-resistance of the obliquebanded leafroller,Choristoneura rosaceana (Harris), to tebufenozide wasreported from laboratory studies before it had been used in commercialorchards in New York State. Bioassays with obliquebanded leafrollerlarvae from tebufenozide and organophosphate susceptible and resistantcolonies were conducted with chlorfenapyr, emamectin benzoate,fenoxycarb, fipronil, spinosad, and tebufenozide to determine ifcross-resistance was present before these new insecticides wereintroduced into commercial orchards. Resistance ratios ranged from 1.1to 3.2 for all insecticides except tebufenozide (12.8). Significantdifferences between susceptible and resistant colonies were found withemamectin benzoate, fenoxycarb, and fipronil. The effect of themetabolic synergists piperonyl butoxide (PBO) and diethyl maleate (DEM)on tebufenozide toxicity was examined to determine mechanisms forobliquebanded leafroller resistance to tebufenozide and potentialmechanisms for other new insecticides. At a concentration of 20 ppm,PBO and DEM significantly synergized the toxicity of tebufenozide inresistant and susceptible colonies (three- to fourfold). Obliquebandedleafrollers may be resistant to new insecticides with distinct modes ofaction even if these compounds have not been previously used incommercial orchards.

We quantified variation in performance under greenhouse conditionsamong seven populations of Scirpophaga incertulas (Walker)from Luzon Island, Philippines, on three rice varieties: ‘IR58’transformed with the cry1Ab gene from Bacillusthuringiensis Berliner, and nontransgenic IR58 and IR62. On IR62,S. incertulas performance did not differ among provinces forany of the 10 parameters measured, but there was a significant effectof town within province for one parameter, 20-d-old larval weight.Larval survival after 48 h on cry1Ab-transformed IR58did not differ significantly among provinces, but did differsignificantly among towns within a province. There was no geographicvariation in larval survival after 48 h on control plants of IR58.Surviving insects from the cry1Ab-transformed IR58 weretransferred to IR62 to complete development. There was no geographicvariation in the percentage of insects completing development to adultemergence and the time required by the transferred female insects tocomplete development. However, there was variation among provinces inmale developmental time. The absence of geographic variation onnontransgenic IR58 and the very limited variation on IR62 indicatedthat there was little variation in general vigor among the S.incertulas populations and thus that the variation in performanceon cry1Ab-transformed IR58 was probably attributable todifferences in susceptibility to Cry1Ab.

Field populations of Hypothenemus hampei (Ferrari),Plutella xylostella (L.), Spodoptera exigua(Hübner), Helicoverpa zea (Boddie), and Bemisiatabaci (Gennadius) were tested for resistance to severalinsecticides commonly used in Nicaragua. Assays were conducted toestimate the LD₅₀s or LC₅₀s and thecorresponding resistance ratios. A diagnostic concentration was used todiscriminate between susceptible and resistant strains of H.hampei. The tests with >6,000 H. hampei adultscollected from six different sites indicate the absence of resistanceto endosulfan. Resistance to cypermethrin, deltamethrin,chlorfluazuron, thiocyclam, and methamidophos was documented in sixfield populations of P. xylostella. High levels ofresistance to cypermethrin and deltamethrin, but moderate levels ofresistance to chlorpyriphos and methomyl, were also documented in twofield populations of S. exigua. Moderate levels ofresistance to cypermethrin, deltamethrin and chlorpyriphos were alsodocumented in three field populations of H. zea. Moderate tohigh levels of resistance to bifenthrin, methamidophos and endosulfanwere documented in four field populations of B. tabaci. Thepresence of significant correlations between LD₅₀s orLC₅₀s suggests the occurrence of cross-resistance orsimultaneous selection for resistance by different insecticides withdifferent modes of action. Our data could not differentiate betweenthese two possibilities. Because insecticides will continue being usedin Nicaragua, a resistance management program is urgently needed. Theimplementation of integrated pest management tactics must beaccompanied by specific regulations for pesticide registration. In thefuture, pesticide registration regulations in Nicaragua should includeperiodic resistance monitoring. The mechanisms to cover the costs ofresistance monitoring and resistance management should also beestablished.

The organophosphorus insecticide, azamethiphos, is widely usedthroughout the world to control the housefly, Muscadomestica (L.). Since its commercial introduction to Denmark in1983 for this purpose, we have monitored the toxicity of azamethiphosto housefly populations at livestock farms throughout the country andcarried out regular field studies. The findings of our field studies,which have revealed a strong potential for resistance development, havebeen born out by regular surveys showing that resistance has increasedin recent years. Through the analysis of a field derived laboratorystrain, we have implicated oxidative and hydrolytic mechanisms togetherwith altered acetylcholinesterase in this resistance. Our field andlaboratory studies have also indicated that resistance is relativelyunstable, and can revert in the absence of selection. The implicationsof our findings for the continued efficacy of azamethiphos arediscussed.

Two methods for estimating the tolerance of common bean genotypesto Empoasca kraemeri Ross & Moore were compared, using ayield trial carried out at Centro Internacional de Agricultura Tropical(CIAT), Cali, Colombia, versus stylet penetration tactics measured byAC electronic feeding monitors. A stylet penetration index was devisedbased on principal component scores of three penetration tacticsidentified (pulsing laceration, cell rupturing, and lancing sapingestion), combined with knowledge of the hopperburn symptoms causedby each tactic. Tolerant genotypes, as classified by the CIAT yieldindex, showed significantly more unprotected yield and lower hopperburnscores than the susceptible control. They also induced performance ofless pulsing laceration (the tactic considered most damaging to theplant), and more of the other two, mitigating tactics, especially cellrupturing. When index values were calculated for each genotype, styletpenetration index values matched those of the yield index for three outof five genotypes: two EMP-coded tolerant lines (‘EMP 385’ and ‘EMP392’) and the susceptible control ‘BAT 41’. Thus, for these threegenotypes, all subsequent hopperburn symptoms are predictable by thetype of feeding behavior performed on them. ‘PorrilloSintético’ and ‘EMP 84’, considered borderline genotypes bythe yield index, were overestimated and underestimated, respectively,by the stylet penetration index. We postulate that, for these twogenotypes, plant physiological responses to feeding (eithercompensatory or heightened sensitivity, respectively) synergize withtype of feeding performed to generate the overall hopperburn condition.This multivariate analysis of electronic monitoring data wassuccessfully used to devise an index of resistance. The implications ofusing the stylet penetration index and the advantages of usingelectronic monitoring in a bean-breeding program are discussed.

Thirteen Betula species were tested for resistanceto the birch leafminer, Fenusa pusilla (Lepeletier), usingno-choice assays. Birch leafminers were able to oviposit into expandingleaves of all Betula individuals tested. Larvae did notsurvive within any of the tested individuals of three species, B.alleghaniensis (Britt.), B. grossa (S. & Z.), andB. lenta (L.). Leafminer eggs deposited into the leaves ofthese species hatched, and larvae fed for a short period before dying.These three species were classified as highly resistant to birchleafminer, based on very low percent of mines (0.6-3.1%) with adiameter >3 mm. Eight species, B. papyrifera (Marsh),B. pendula (Roth), B. turkestanica (Litvin),B. glandulifera (Regal), B. ermanii (Cham.),B. platyphylla variety japonica [(Miq.) Hara],B. populifolia (Marsh) and B. maximowicziana(Regal) were classified as susceptible, with percent of mines >3 mmdiameter of 87-94%. Two species, B. costata (Trautv.) andB. davurica (Pall.), displayed intermediate and variableresistance. B. davurica exhibited a mechanism of resistancenot observed in the other species. Eggs oviposited into the leaves ofresistant B. davurica individuals became surrounded by anarea of discolored and necrotic tissue, and died. This responseresembles the programmed cell death associated with a hypersensitiveresponse.

Plant resistance is a promising control method for the two mostdamaging insect pests of maize, Zea mays L.: the Europeancorn borer, Ostrinia nubilalis (Hübner), and thewestern corn rootworm, Diabrotica virgifera virgiferaLeConte. Fifteen experimental lines of maize, derived from a backcrossbreeding program designed to introgress resistance to European cornborer from Peruvian maize into two U.S. Corn Belt adapted inbred lines,were evaluated for resistance to European corn borer and western cornrootworm. The experimental lines were in the second generation ofbackcrossing. All experimental lines were resistant to leaf bladefeeding by European corn borer. These lines had low levels of2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one, a chemical commonlyassociated with leaf blade feeding resistance, indicating that this wasnot the mechanism of resistance to leaf blade feeding in these lines.Eleven experimental lines were resistant to leaf sheath and collarfeeding by European corn borer. Useful sources of European corn borerovipositional nonpreference and root feeding resistance to western cornrootworm were not identified. Some of the lines evaluated in this studymay provide useful sources of resistance to both leaf blade and leafsheath and collar feeding by European corn borer.

Repeated sampling of rural maize stores in Benin was conducted toevaluate published parameters of a sequential sampling plan for anegative binomial distribution to determine pest status forProstephanus truncatus (Horn) and Sitophiluszeamais Motschulsky. A computer program was used to rerandomizethe data and evaluate the effects, in terms of average sample numberand error rates, of different sampling plan parameter values. Withrespect to P. truncatus, lower and upper thresholds of 0.2and 1.0 insects per ear and parameter values of k = 0.2and α = β = 0.1 were found to be adequate. With respectto S. zeamais, lower and upper thresholds of 10 and 20insects per ear and parameter values of k = 1.0 andα = β = 0.1 were found to be adequate. Simplifiedsampling rules were proposed in which 11 ears should be sampled and ifno P. truncatus are found, the population is low; otherwisethe Wald plan should be followed. Owing to the lower per capita rate ofdamage, effective simplified sampling rules for S. zeamaiswere difficult to construct. An evaluation of the visual assessmentscale using whole ears showed that a visual scale estimating percentagedamage rather than percentage loss, might be easy to construct andpreferable for traders. Further work is needed to improve theusefulness of the visual scale in pest management decision support.

As part of the eradication program for recent introductions of thelonghorned beetle Anoplophora glabripennis (Motschulsky) inthe United States, wood from infested trees is chipped and incinerated.Two tests were conducted to evaluate the efficiency of chipping woodfrom infested trees on the survival of the beetle. In the first test,plastic worms were used as surrogates for larvae of the beetle. Plasticworms of different sizes were placed in holes drilled in logs of sugarmaple, Acer saccharum Marsh. In a second test, in additionto plastic worms, we used different instars and pupae of gypsy moth,Lymantria dispar (L.) (Lepidoptera: Lymantriidae); larvae ofthe beetle Phyllophaga annina Lewis (Coleoptera:Scarabaeidae); and larvae of an unidentified weevil (Coleoptera:Curculionidae). Although chipping did not result in an obvious damageto all plastic worms, it did kill all larvae and pupae of insectsplaced in holes of maple logs. The overall recovery rate (percentrecovered) for the plastic worms was 96% in the first (1997) test, and71 and 98% for 10 and 40 mm long plastic worms in the second (1998)test, respectively. Logistic regression analysis of the data from thefirst experiment indicates that larger worms receive more severedamage. Size of logs did not have a significant effect on the level ofdamage received by plastic worms. All recovered insects were severelydamaged after chipping logs and we could not determine recovery rates.Results of the two tests indicate that chipping wood from infestedtrees without incineration of the resulting chips provides a highlyeffective method for destroying wood inhabiting insect pests such asA. glabripennis. The elimination of incineration savesconsiderable resources while effectively eliminating risks associatedwith movements of wood containing living wood-boring insects.

The mechanical impact of rice polishing on the rice weevil,Sitophilus oryzae (L.), and the subsequent postpolishingeffects associated with rice quality were studied. “Brown” rice(not polished), “White (infest then polish)” rice, and “White(polish then infest)” rice were used with different polishing processintensities and different initial weevil densities. Weevil progeny weremore numerous in Brown than in White (infest then polish) or White(polish then infest) rice. Polishing corresponding to a weight loss of11% in rice generated an immediate mortality of ≈40%; thesubsequent mortality caused by rice quality was also 40% (total>80%). A polishing process corresponding to 14 and 16% of riceweight loss generated a drastic mortality in the weevil population(>95%). The progeny per adult weevil was similar with high and lowinitial weevil densities. The development of weevil progeny was alsodelayed by about 1 wk in White (infest then polish) rice compared withBrown rice. Furthermore, weevil adults of the progeny weresignificantly heavier in Brown than in White (infest then polish) orWhite (polish then infest) rice.

Studies were conducted at two flour mills where male Indian mealmoths, Plodia interpunctella (Hübner), were capturedusing pheromone-baited traps. Objectives were to determine thedistribution of male P. interpunctella at differentlocations in and around the mills throughout the season, and to monitormoth activity before and after one of the mills was fumigated withmethyl bromide to assess efficacy of treatment. Commercially availablesticky traps baited with the P. interpunctella sex pheromonewere placed at various locations outside and within the larger of thetwo mills (mill 1). Moths were captured inside mill 1 after methylbromide fumigations. The highest numbers of P.interpunctella were caught outside the facility and at groundfloor locations near outside openings. Additional traps placed in therooms above the concrete stored-wheat silos at mill 1 during the secondyear captured more moths than did traps within the mill’s productionand warehouse areas. In another study, moths were trapped at variousdistances from a smaller flour mill (mill 2) to determine thedistribution of moths outdoors relative to the mill. There was anegative correlation between moth capture and distance from thefacility, which suggested that moth activity was concentrated at ornear the flour mill. The effectiveness of the methyl bromidefumigations in suppressing moth populations could not be assessed withcertainty because moths captured after fumigation may have immigratedfrom outside through opened loading bay warehouse doors. This studydocuments high levels of P. interpunctella outdoors relativeto those recorded inside a food processing facility. Potential forimmigration of P. interpunctella into flour mills and otherstored product facilities from other sources may be greater thanpreviously recognized. Moth entry into a food processing facility afterfumigation is a problem that should be addressed by pest managers.

Studies were undertaken to determine whether irradiation treatmentat 250 Gy, an accepted treatment for disinfestation of fruit flies inspindaceous fruits from Hawaii, would also disinfest fruit of twospecies of Cryptophlebia. Cryptophlebia illepida (Butler)was determined to be more tolerant of irradiation thanCryptophlebia ombrodelta (Lower); therefore, C.illepida was the focus for detailed tests. Using the criterion ofsuccess in developing to the adult stage, the pattern of tolerance toirradiation in C. illepida was generally eggs < earlyinstars < late instars < pupae. The most tolerant stagepotentially occurring in harvested fruits was late (fourth and fifth)instars. Development to adult was reduced slightly in late instarsreceiving an irradiation dose of 62.5 Gy, whereas development to adultwas dramatically reduced in late instars receiving irradiation doses≥125 Gy. No C. illepida larvae receiving an irradiationdose ≥125 Gy emerged as adults and produced viable eggs, indicatingsterility can be achieved at doses well below 250 Gy. In large scaletests, when 11,256 late instars were irradiated with a target dose of250 Gy, 951 pupated (8.4%) and none eclosed as adults. Within thepupal stage, tolerance increased with age; 7- to 8-d-old pupae (theoldest pupae tested) treated with an irradiation dose of 125 Gyproduced viable offspring, whereas those treated with a dose of 250 Gyproduced no viable offspring. Irradiation of adults with a target doseof 250 Gy before pairing and mating resulted in no viable eggs.Irradiation of actively ovipositing adult females resulted in nosubsequent viable eggs. Therefore, the irradiation quarantine treatmentof a minimum absorbed dose of 250 Gy approved for Hawaii’s fruits willeffectively disinfest fruits of any Cryptophlebia inaddition to fruit flies.