Noctuid Larvae Research Articles

Seasonal variation in leaf characteristics and food selectionby larval noctuids on an evergreen Mediterranean shrub

Despite year round availability of foliage, abundance of generalist noctuid larvae (Lepidoptera: Noctuidae) in evergreen-dominated Mediterranean forests has a narrow, distinct spring peak. This restricted larval period has been suggested to result in part from avoidance of the nutritionally poor mature foliage, and preference for nutritionally superior spring-produced young leaves. This study examines this hypothesis by (i) documenting differences in nutritional characteristics between expanding (April) and mature (June) young leaves of the evergreen Mediterranean shrub Daphne laureola L. (Thymelaeaceae), and (ii) experimentally studying the feeding preferences of noctuid larvae for young leaves, old leaves (≥ 1 yr old), and developing fruits of this species in one south-eastern Spanish locality. Young leaves of D. laureola declined in nutrient concentration and specific dry mass from April to June. The responses of noctuid larvae, in terms of both relative preference and total consumption, to this seasonal variation in chemical and physical features of young leaves were also investigated. When noctuid larvae were simultaneously offered young leaves, old leaves and developing fruits, they exhibited similar preferences for young leaves and developing fruits, and rejected old leaves developed during the previous year. Noctuid larvae did not modify their consumption of young leaves relative to old leaves and developing fruits in response to seasonal changes. Food selection patterns exhibited by D. laureola noctuid herbivores, notably the rejection of old leaves in favour of young ones, are consistent with the hypothesis relating restricted larval periods of these generalist consumers with the low food value of the previous season leaves of evergreen Mediterranean plants.

Effects of seed potato tuber treatment with imidacloprid on some soil and foliar insects in Croatia

The treatment of seed potato tubers by imidacloprid, as well as the standard granular insecticides applied in the furrow, did not, in four years of trials, sufficiently prevent damage from wireworms, noctuid larvae and mole crickets to potato tubers. The main reason for this failure is the spatial and temporal distance between the application of insecticides and the moment when their action is needed. On the other hand, the effects of imidacloprid applied as seed tuber treatment on the larvae of the Colorado potato beetle was very good: depending upon conditions, it lasted from at least 55, to 70 days at the most. It protected the foliage from any substantial damage from the entire first generation, and ensured high yields. Therefore a decision on seed tuber treatment with imidacloprid in Croatia should primarily depend upon the cost/benefit calculation based on damage expected from the CPB (or aphids), and not from soil insect pests.

Co-infection of Manduca sexta larvae with polydnavirus from Cotesia congregata increases susceptibility to fatal infection by Autographa californica M Nucleopolyhedrovirus

We investigated pathogenesis of Autographa californica M Nucleopolyhedrovirus in the semipermissive host, Manduca sexta, using a lacZ recombinant virus (AcMNPV- hsp70/ lacZ) to track the temporal progression of infection. Results from time course studies monitoring infections initiated orally in fourth instars demonstrated that primary infection of midgut columnar cells began at 3 h post inoculation (hpi). We observed secondary infections in midgut-associated tracheae as early as 9 hpi, showing that the early events of pathogenesis in M. sexta are similar to those of permissive noctuid larvae. In M. sexta, however, unlike in permissive hosts, hemocytes rapidly surrounded infected tracheal cells and formed capsules. Subsequently, baculovirus infections failed to spread and ultimately were cleared, suggesting that a cellular immune response had been triggered. To assess the effects of immunosuppression on baculovirus-induced disease, we compared the outcome of infections in immunocompetent hosts with those that were immunocompromised either by parasitization with the braconid, Cotesia congregata, or by injection of the parasitoid's polydnavirus. During the first 9 days after inoculation, parasitized and polydnavirus-inoculated M. sexta larvae died more quickly and at higher levels than nonparasitized and sham-injected controls, suggesting that the cellular immune response was a factor in conferring resistance to fatal infection by AcMNPV- hsp70/ lacZ.

INDUCED RESPONSES TO HERBIVORY IN WILD RADISH: EFFECTS ON SEVERAL HERBIVORES AND PLANT FITNESS

Induced responses to herbivory are changes in plant quality following initial damage by herbivores. These changes can negatively affect subsequent herbivores. I studied induced responses in annual wild radish plants, Raphanus raphanistrum and R. sativus (Brassicaceae), which included increased density and total number of setose trichomes on newly formed leaves of previously damaged plants compared to undamaged controls. I also characterized the effects of induced responses on the preference and performance of several herbivores and the net consequences for plant performance in the field. Wild radish plants damaged by caterpillars or sprayed with a natural plant response elicitor, jasmonic acid, supported reduced growth of generalist noctuid larvae compared to unmanipulated control plants. Induced responses did not affect the growth of specialist Pieris rapae larvae. In choice and no-choice experiments, induction reduced the feeding by noctuid larvae but did not reduce gross growth efficiency, an indicator of insect growth per unit of plant material consumed. Finally, colonization of plants by leafminers was lower on plants that received previous damage, compared to controls. In field experiments conducted over 2 yr, herbivory by naturally occurring grasshoppers was lower on induced plants than on both unmanipulated controls and leaf damage controls (plants with leaf area removed without the associated induced response). Plant fitness, as estimated by fruit and seed production, was enhanced for induced plants compared to controls. These results demonstrate that induced responses to herbivory can reduce the preference and performance of a variety of herbivores and ultimately increase plant fitness in natural environments. In order for a plant trait to be characterized as a defense, it must increase plant fitness in environments with herbivory. Although much attention has been given to detecting costs of plant defenses, this is one of the first systems for which fitness benefits of induced resistance have been demonstrated.

Induced Responses to Herbivory in Wild Radish: Effects on Several Herbivores and Plant Fitness

Induced responses to herbivory are changes in plant quality following initial damage by herbivores. These changes can negatively affect subsequent herbivores. I studied induced responses in annual wild radish plants, Raphanus raphanistrum and R. sativus (Brassicaceae), which included increased density and total number of setose trichomes on newly formed leaves of previously damaged plants compared to undamaged controls. I also characterized the effects of induced responses on the preference and performance of several herbivores and the net consequences for plant performance in the field. Wild radish plants damaged by caterpillars or sprayed with a natural plant response elicitor, jasmonic acid, supported reduced growth of generalist noctuid larvae compared to unmanipulated control plants. Induced responses did not affect the growth of specialist Pieris rapae larvae. In choice and no-choice experiments, induction reduced the feeding by noctuid larvae but did not reduce gross growth efficiency, an indicator of insect growth per unit of plant material consumed. Finally, colonization of plants by leafminers was lower on plants that received previous damage, compared to controls. In field experiments conducted over 2 yr, herbivory by naturally occurring grasshoppers was lower on induced plants than on both unmanipulated controls and leaf damage controls (plants with leaf area removed without the associated induced response). Plant fitness, as estimated by fruit and seed production, was enhanced for induced plants compared to controls. These results demonstrate that induced responses to herbivory can reduce the preference and performance of a variety of herbivores and ultimately increase plant fitness in natural environments. In order for a plant trait to be characterized as a defense, it must increase plant fitness in environments with herbivory. Although much attention has been given to detecting costs of plant defenses, this is one of the first systems for which fitness benefits of induced resistance have been demonstrated.

Random foraging by herbivores: complex patterns may be due to plant architecture

Random foraging by herbivores: complex patterns may be due to plant architecture

Variation in Susceptibility of Noctuid (Lepidoptera) Larvae Attacking Cotton and Soybean to Purified Endotoxin Proteins and Commercial Formulations of Bacillus thuringiensis

Susceptibility of Heliothis virescens (F.), Helicoverpa zea (Boddie), Pseudoplusia includens (Walker), Spodoptera exigua (Hubner), and Spodoptera frugiperda (J. E. Smith) to purified endotoxins and commercial formulations of Bacillus thuringiensis Berliner was measured in a wide range of colonies collected from 8 states in the U.S. Cotton Belt during 1992 and 1993. Results indicated that field-collected colonies of H. virescens, H. zea, P. includens, and S. frugiperda were as susceptible as laboratory-reared colonies and those reported in the literature to the purified endotoxin proteins Cry1Ac and Cry1Ab or the commercial formulations Javelin WG, Dipel ES, and Condor OF in diet-treated assays. Colonies of S. exigua collected from transgenic cotton expressing endotoxin protein had elevated median lethal concentrations (LC50s) compared with a colony collected from nontransgenic cotton or those from laboratory colonies. Ranges of LC50s for field-collected colonies of H. virescens generally were similar to the ranges observed for laboratory colonies and similar to those reported in the literature. Wider ranges of variation in LC50s were observed among populations of H. zea and S. exigua than among populations of the other species. However, the highest LC50 observed for H. zea was no higher than those reported in the literature. Only a few colonies of P. includens and S. exigua were tested. P. includens susceptibility was generally greater than that of H. virescens and less than that of H. zea. S. frugiperda was the least susceptible species studied. Variability in LC50s obtained with Cry1Ac ( r = 0.702) correlated with variability in LC50s for Cry1Ab across 13 colonies of H. virescens exposed to both proteins. Colonies of H. zea and H. virescens were pooled into single colonies and selected with the insecticidal proteins to produce endotoxin-resistant strains. Selection for resistance in H. virescens was not successful, but a strain of H. zea was selected that had elevated LC50s (10 times) after 2 generations and very high LC50s compared with a susceptible laboratory strain (100 times) after 8 generations, suggesting that H. zea has the genetic capacity to develop resistance to endotoxin proteins.

Effect ofMelia azedarach fruit extract on juvenile hormone titer and protein content in the hemolymph of two species of noctuid lepidopteran larvae [insecta: Lepidoptera: Noctuidae

The effect of an enriched methanolic extract ofMelia azedarach L. (Meliaceae) fruits on the size of the corpora allata (CA), the juvenile hormone (JH) titer and the protein content in the hemolymph of two lepidopteran pests in Egypt,Spodoptera littoralis (Boisd.) andAgrotis ipsilon (Hufn.), was studied. Different concentrations of the extract were incorporated into an artificial diet on which the larvae were allowed to feed. InS. littoralis, a significant reduction in the CA volume of larvae treated at the 1000 ppm extract levelvs that of control larvae was observed. In A.ipsilon, a reduction was found in the right CA gland only. Larvae of both species that had fed on a diet withMelia extract had a higher mean JH-II titer in the hemolymph than did control larvae. In both species, the content of hemolymph protein was decreased significantly after feeding for 6 days on a diet treated with concentrations above 50 ppm extract, followed by 6 days on a normal diet. The results show that aM. azedarach fruit extract has an effect on the neuroendocrine control in the insects. The effect on the hemolymph protein levels is discussed in connection with changes in the morphology/physiology of the gut.

Dietary Protein and Chlorogenic Acid Effect on Baculoviral Disease of Noctuid (Lepidoptera: Noctuidae) Larvae

Insecticidal pathogens such as baculoviruses are currently under intensive development as biorational agents for the control of lepidopteran pests. However, because the efficacy of these orally infective viruses is influenced by host diet, our ability to use baculoviruses effectively in an integrated pest management program requires understanding the influence of dietary components on the disease process. Nutritional stress caused by differences in the quality (casein or soy) or quantity (0–8%) of dietary protein altered the postinfectional course of disease caused by Autographa californica M nucelopolyhedrovirus in 2 species of noctuids, Heliothis virescens (F.) and Trichoplusia ni (Hübner). Lethal times of larvae infected with either the wild-type virus or a recombinant expressing a scorpion toxin (AaIT) derived from this parent virus were similarly affected by dietary protein. In general, the higher the level of dietary protein the shorter the lethal times. However, the influence of protein quality on lethal times depended on the insect species tested. The effect of chlorogenic acid on disease depended on dietary protein levels. At high protein concentrations, chlorogenic acid decreased speed of kill; whereas, at low protein levels, the phenolic had the opposite effect. The common factor among all treatments was that the faster larvae grew, the faster they died from viral infection. We suggest that insects that grow faster may support faster rates of viral replication in infected hosts. From an ecological perspective, it is possible that plants of higher protein content may increase the potential for the development of baculoviral epizootics in insect populations.

Laboratory and Field Comparisons of Strains of Bacillus thuringiensis for Activity Against Noctuid Larvae Using Granular Formulations (Lepidoptera)

The toxicity of 6 strains of Bacillus thuringiensis representing 4 serovars, aizawai, galleriae, kurstaki, and kumamotoensis, were evaluated in laboratory and field studies for activity against 3 lepidopteran crop pests, Heliothis virescens (F.), Spodoptera exigua (Hübner), and Trichoplusia ni (Hübner). Results of laboratory tests showed that some B. thuringiensis strains isolated from Mexico (GM-7 and GM-I0), were sufficiently toxic to warrant further investigation as potential bioinsecticides for lepidopteran control. Nixtamalized corn flour was used to create a B. thuringiensis granule formulation that remained toxic for at least 2 yr. Field tests were conducted in 1994 and 1995 on corn plots in a semiarid region in central Mexico. Granular formulations were made with 2% (wt:wt) or 4% (wt:wt) of a spore-crystal B. thuringiensis concentrate and tested with carbaryl and Dipel 2X. In 1994, the corn yields obtained from plots treated with 2 strains from the Howard Dulmage collection (HD-187 and HD-193-kurstaki and galleriae, respectively) and 1 Mexican strain (GM-lO, aizawai) at 2% were significantly higher than from plots treated with Dipel 2X or the untreated control. Formulations of 4% containing strains GM-7, GM-I0, HD-187, HD-193, and HD-263 provided better insect control than formulations made with C-4. These tests indicated that B. thuringiensis survived in the nixtamalized flour matrix complex and was effective in causing pest reduction. In the 1995 field test, the 3 most toxic strains were evaluated individually or by mixing 2 in the same granular formulation at a total dose of 3%.The highest yields of com were obtained from plots treated with strain HD-263 (kurstaki, which had originally shown the highest efficacy in laboratory bioassays, and with strain GM-I0 (aizawai), formulated 2 yr earlier. These data suggest that the product can be produced and retain shelf life suitable for commercialization.

Influence of induced plant defenses in cotton and tomato on the efficacy of baculoviruses on noctuid larvae

Constitutive phenolase activity of plants has a profound ability to modulate disease in insects caused by baculoviruses. We investigated the influence of damage-induced plant phenolic oxidases in cotton and tomato on mortality caused by two different baculoviruses in their respective hosts, Heliothis virescens (L.) and Helicoverpa zea (Boddie). For both plant species, peroxidase (POD) and phenolic levels were predictive of larval mortality caused by baculoviruses. The higher the POD activity, the lower the mortality in both hosts. Different classes of phenolics (e.g., monohydroxyphenolics vs. catecholic phenolics) in combination with POD activity had different effects on the severity of viral disease depending upon mixture, which implies that viral efficacy is predictable only if total chemical content of the plants is specified. Inhibition of baculoviral disease by plant phenolase activity has potential implications for the compatibility of baculoviruses with induced resistance in IPM programs.

INHIBITION OF BACULOVIRAL DISEASE BY PLANT-MEDIATED PEROXIDASE ACTIVITY AND FREE RADICAL GENERATION

The susceptibility of noctuid larvae to baculoviral infection is markedly affected by phytochemicals ingested during the acquisition of viral inoculum on foliage. We hypothesized that a major process causing phytochemical inhibition of viral disease is phenolic oxidation by phenolases, particularly peroxidase (POD), which subsequently generates free radicals. To test this hypothesis, we manipulated the chemical interactions in foliage of cotton, tomato, and lettuce by application of antioxidants, prooxidants, enriched extracts of phenolases, and/or phenolic substrates. Larvae of Heliothis virescens or Helicoverpa zea that received viral inoculum on treated foliage were less likely to die from viral infection the higher the POD activity of this foliage. Furthermore, the higher the POD activity, the more free radicals were generated in crushed foliage, and the more free radicals generated, the lower the incidence of viral disease. We present a series of reactions hypothesized to lead to inhibition of viral disease by free radicals, the generation of which is mediated, at least in part, by POD. Phenolic redox cycling catalyzed by POD involving clastogenesis (generation of H2O2) appeared to be a critical driver of phytochemical reactions leading to free radical generation and inhibition of baculoviral disease in their noctuid hosts. We also report application of an assay for the detection of free radicals by using methemoglobin as a new modification of this method for detecting radicals in plant foliage in the immediate aftermath of an oxidative burst.

Host recognition by the specialist endoparasitoidMicroplitis croceipes (Hymenoptera: Braconidae): Role of host- and plant-related volatiles

The specialist parasitoid Microplitis croceipes Cresson can parasitize only noctuid larvae in the genera Helicoverpa and Heliothis. To be successful in their search for hosts, the ability to distinguish hosts from nonhosts feeding on the same plant is beneficial. In flight tunnel experiments, we found that prior to landing on the odor source M. croceipes were able to distinguish volatiles released from frass of host larvae (Helicoverpa zea Boddie) and nonhost larvae (Spodoptera exigua Hubner and Spodoptera frugiperda J. E. Smith) fed on cotton. However, an initial contact experience with frass of cotton-fed host larvae appeared to be critical for this ability. Wasps that had antennated frass of host larvae fed pinto bean diet were equally attracted to frass of host and nonhost larvae fed on pinto bean diet. In short-range walking experiments, wasps located cotton-fed host larvae faster than diet-fed larvae, regardless of their experience. Wasps that had antennated frass of cotton-fed host larvae were less attracted to cotton-fed nonhost larvae, compared to host larvae, and preferred to sting host larvae. Plant-related volatiles in host frass and larvae appear to play a major role in the successful location of host larvae.

Variation in Herbivory within and among Plants of Daphne Laureola (Thymelaeaceae): Correlation with Plant Size and Architecture

1 Herbivory by noctuid moth larvae (Lepidoptera, Noctuidae) on plants of Daphne laureola L. (Thymelaeaceae) was studied under natural conditions in a south-eastern Spanish montane habitat. The main objective of the study was to determine how size and architectural features correlated with herbivory level (mean percentage leaf area removed by the end of the larval growth season) and herbivore load (mean number of caterpillars recorded per day) both among and within plants. 2 A significant correlation was found between herbivore load and herbivory level of individual plants. Herbivory levels differed widely (range = 0.1-12.8% leaf area) and were considerably smaller than those often used in artificial defoliation experiments. 3 Variation among plants in the incidence of noctuid larvae was directly related to the number of leaf whorls, and inversely to the mean basal diameter of stems. These responses to size and architectural traits may be explained by discrimination by ovipositing females. 4 Within plants, larvae preferentially selected leaf whorls having shorter supporting stems and lower branching orders. Movement costs may be reduced by larvae using plant architectural traits as cues for within-plant food selection. 5 The reasons for and potential implications of the different features used by adult noctuids discriminating between plants and by their larvae selecting leaf whorls are discussed.

Antinutritive and toxic components of plant defense against insects

Chemical defense of the tomato plant against noctuid larvae is argued to result from suites of interactive chemical traits that simultaneously impair the acquisition of nutrients and toxify the insect. Defense results from tomatine, catecholic phenolics and phenol oxidases, proteinase inhibitors, and lipoxygenase. The catalytic role of plant oxidative enzymes in activating a variety of defense mechanisms is discussed. It is argued that the terms “digestibility reducer,” “toxin,” and “nutrient” signify ecological outcomes, not properties of molecules. Current views on the roles and the modes of activity of plant natural products against herbivorous insects are challenged. It is proposed that chemical context and mixture are critical determinants of biological activity, and that viewing natural products as isolated defensive factors is often misleading. © 1996 Wiley-Liss, Inc.

Control of Armyworms on Bell Pepper in West-Central Florida, Fall 1992

Abstract Transplants were set 2 Sep, 12 inches apart on 8-inch-high beds of EauGallie fine sand covered with white polyethylene mulch. Each plot consisted of a single row with rows on 5 ft centers. Treatments were replicated 4 times in a randomized complete blocks design and were applied with a 2.5 gal, hand-held CO2-powered sprayer on 28 Sep, 8, 15, 21, 28 Oct, 4, 11, 18 and 25 Nov. The sprayer was fitted with a single nozzle with a D-5 disk and #45 core and delivered 60 gpa at 60 psi. On 19 Oct and 9 Nov, the numbers of beet and southern armyworm larvae were counted on each plant. The data were combined over the sampling dates. On 10 Nov, the five plants in each plot most severely damaged by the broad mite were rated 1-4 for increasing damage. Fruit were harvested on 25 Nov, 9 and 16 Dec and the number and weight of undamaged fruit and the number and weight of fruit damaged by noctuid larvae were determined. Fruit with slight feeding damage only on the stem or calyx were considered marketable. Fruit with either slight or severe damage on the fruit wall were considered unmarketable.

Seasonality and life cycles of woody plant‐feeding noctuid moths (Lepidoptera: Noctuidae) in Mediterranean habitats

Abstract. The annual cycle of noctuid moths feeding as larvae on the foliage of eighteen woody plant species (belonging to ten different families) was studied at two southeastern Spanish Mediterranean forest habitats. Two questions were addressed in this study. (1) Does the rigorous (hot and dry) summer season characteristic of the Mediterranean‐type climate impose a constraint on noctuid life histories? (2) Are there detectable differences in abundance or phenological patterns between the noctuid assemblages feeding on evergreen and winter‐deciduous trees and shrubs? Regardless of their leaf persistence habit, the majority of woody species studied had short shoot growth and leaf production periods in spring. Abundance of noctuid larvae peaked in May‐June, shortly after host plants started to produce new leaves. Virtually no noctuid larvae were found on the foliage of the woody species studied at other times of year. Abundance and seasonal pattern of occurrence of larvae were similar on evergreen and deciduous food plants. In contrast with the unimodal seasonal pattern exhibited by larvae, the abundance of adult moths (assessed by light trapping) showed two distinct peaks in early summer and early autumn, and a marked minimum in mid‐summer. Most woody plant‐feeding noctuids recorded in this study (86% of species, about 95% of individuals) were univoltine. Univoltine species fell into one of two distinct life history categories, corresponding to pre‐ and post‐summer flight periods. These two contrasting phenologies were associated with a bimodality in the duration of the pupal stage (‘short’ versus ‘long’), and were closely related to taxonomical affiliation at the subfamily level. Within the ‘short’ pupal duration group, some species mate and oviposit shortly after emergence and pass the dry season in the egg stage, while others remain as potentially active, non‐reproductive adults over most of the summer and mate by the end of that season. Species in the ‘long’ pupal duration group pass the summer in pupal or prepupal stage. In the Mediterranean habitats studied, the adversity of the summer dry season seems to have led to a woody plant‐feeding noctuid species assemblage almost entirely made up of univoltine species that concentrate their larval phases when suitable food (young leaves) is most abundant, and ‘avoid’ mid‐summer as a flight time by emerging either shortly before or shortly after the adverse summer drought period. Year‐round foliage availability afforded by dominant evergreen plants does not seem to have influenced the seasonal organization of noctuid cycles in any substantial way.

Growth inhibitory and antifeedant effects of azadirachtin on six noctuids of regional economic importance

AbstractThe comparative efficacy of azadirachtin, the major active ingredient in the botanical insecticide neem, as a larval growth inhibitor and feeding deterrent was determined for six species of noctuids of economic importance: the black army cutworm, Actebia fennica (Tausch.), the bertha armyworm, Mamestra configurata Walker, the variegated cutworm, Peridroma saucia Hubner, the zebra caterpillar, Melanchra picta (Harr.), the Asian armyworm, Spodoptera litura (Fab.), and the cabbage looper, Trichoplusia ni Hubner. When added to an artificial diet, azadirachtin inhibited neonate larval growth of all species in a dosedependent fashion. EC50 values (dietary concentration reducing larval growth by 50% relative to controls) following ten days of feeding ranged from 0.12 to 0.24 mg kg−1 but without significant differences between species. However, when second‐instar larvae were offered a choice, only larvae of P. saucia and S. litura discriminated between a control diet and diet containing azadirachtin at concentrations up to 0.4 mg kg−1. A more sensitive behavioural bioassay using fourth‐instar larvae indicated that S. litura was the most sensitive to the antifeedant effects of azadirachtin (EC50 = 1.25 ng cm−2), whereas A. fennica was the least (EC50 = 40.7 ng cm−2). Topical treatment of fourth‐instar larvae with 50 or 100 ng of azadirachtin resulted in significant inhibition of subsequent growth, diet consumption, and dietary utilization. However, A. fennica and S. litura are less inhibited that the other four species. The present study indicates that behaviourbased bioassays alone do not characterize the total effect of azadirachtin on noctuid larvae.

Leafminer, Armyworm and Tomato Pinworm Control on Fresh Market Tomatoes In West-Central Florida, Spring 1992

Abstract Transplants were set 10 Feb, 15 inches apart on 8-inch-high by 30-inch wide beds of EauGallie fine sand covered with black polyethylene mulch. Each plot consisted of a single 15 ft row with rows on 5 ft centers. Plants were grown staked and were irrigated by seepage subirrigation. Insecticide treatments were replicated 4 times in a randomized complete block design, applied with a 2.5 gal, hand-held CO2-powered sprayer on 19 Mar, 3, 9, 16, 23 Apr, 8, 15, 21 and 29 May. The sprayer was operated at 60 psi and delivered 60 gal/acre using a single nozzle fitted with a D-5 disk and #45 core. On 2 and 4 Jun, the number of leafrolls produced by larvae of the tomato pinworm was counted in a 4 minute search of each plot. On 4 Jun, the number of small (<0.5 inch long) and large (≥0.5 inch long Liriomyza) spp. leafmines was counted in a 1 minute search of selected treatments. Fruit was harvested on 14 and 26 May and the number and weight of undamaged fruit and the number and weight of fruit damaged by noctuid larvae [primarily the southern armyworm] were determined.

Control of Armyworms on Bell Pepper in West-Central Florida, Fall 1991

Abstract Transplants were set 5 Sep, 12 inches apart on 8-inch-high beds of EauGallie fine sand covered with white polyethylene mulch. Each plot consisted of a single row with rows on 5 ft centers. Treatments were replicated 4 times in a randomized complete block design and were applied with a 2.5 gal, hand-held CO2-powered sprayer on 27 Sep, 4, 10, 17, 24, 31 Oct, 8, 14, 22 Nov and 12 Dec. The sprayer was operated at 60 psi and delivered 55 gal/acre for the first spray and 80 gal/acre for the remaining sprays. The sprayer was outfitted with a single nozzle with a D-5 disk and #45 core. On 8 Nov, the numbers of beet and southern armyworm larvae were counted on each plant. Fruit were harvested on 27 Nov and 16 Dec and the number and weight of undamaged fruit and the number and weight of fruit damaged by noctuid larvae were determined.