Lygus Research Articles

Production and Predator-Induced Release of Volatile Chemicals by the Plant Bug Lygus hesperus

Both sexes of adult western tarnished plant bug, Lygus hesperus Knight (Heteroptera: Miridae), released three volatile chemicals in relatively large amounts when attacked by ants (Pogonomyrmex rugosus and Solenopsis xyloni) or when grabbed by forceps, as determined by solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The relative amounts of the volatile compounds, hexyl butyrate, (E)-4-oxo-2-hexenal, and (E)-2-hexenyl butyrate, absorbed by SPME as a percentage of the largest were 100%, 44%, and 4%, respectively, from females, and 83%, 37%, and 3% from males. Both ant species were repelled by the defensive discharges (confirmed by SPME) when the ants attacked L. hesperus adults. Sexually mature L. hesperus were individually extracted in pentane to quantify the mean amounts of hexyl butyrate (14.9 microg/female; 10.3 microg/male), (E)-4-oxo-2-hexenal (2.7 microg/female; 3.1 microg/male), and (E)-2-hexenyl butyrate (1.2 microg/female; 0.6 microg/male). (E)-4-Oxo-2-hexenal was unstable in solvent when in contact with a macerated adult, but relatively stable when the solution was decanted within minutes. The production of the three major volatile components began soon after the emergence of the adult and amounts increased for about 5-10 d with little or no increase thereafter. Minor additional constituents were cross-correlated in many cases with the three major ones. A cost of defensive secretion is suggested for females but not for males, because heavier females produced more volatile compounds than lighter females. The initial discharge percentage, defined as the proportion of volatile compounds initially present that is discharged to defend against predation was estimated at about 50% in males and 70% in females. Newly eclosed adults did not produce volatile chemicals until 2 d after molting.

The effect of lygus bugs ( Exolygus prantensis L.) on marketing price of red lentil in Anatolia, Turkey

The aim of this study was to assess the damage commonly known as chalky spot syndrome caused by the lygus bug on red lentil and the negative relation to the resulting marketing price in the commodity market of Sanliurfa, Turkey. Analysis showed that there was significant difference among the content (%) of chalky spot damage (range 1.45–29%) of lentil samples collected from the farmers who brought their crops to sell in the commodity market and this was negatively related to the market price that farmers received. Marketing prices of samples were also found to be significantly affected. The correlation between visually inspected chalky spot damage (%) and that of decorticated and weighted lentils was found to be positive and significant. Marketing prices also were found to be negatively correlated with the results of both inspection methods. Further analysis indicated that regression equations could be used for price estimation of lentil with different ratios of chalky spot. It was concluded that 10% chalky spot can reduce the marketing price from 0.426 to 0.396 $ kg −1 when visually inspected and from 0.438 to 0.358 $ kg −1 when decorticated.

The Effect of Rainfall on the Abundance of Tarnished Plant Bug Nymphs [Lygus lineolaris (Palisot)] in Alfalfa Fields

Rainfall has generally been overlooked as a regulator of insect population size, especially for mirids (Hemiptera). During a 13-year field study in northwestern New Jersey, total May-June rainfall ranged from 6.5 to 10.7 inches (165–272mm). The highest rainfall reduced first generation nymphs of the tarnished plant bug, Lygus lineolaris (Palisot) (Miridae), in alfalfa by 50%. This reduction was likely mechanical (raindrops knocking the mirids off the plants) rather than biotic, because infections by nematodes and a fungus disease were not significantly increased. The rainfall-reduced mirid populations also had less mortality by the introduced parasite Peristenus digoneutis Loan (Braconidae), probably a result of the lower host density (density dependence). Conversely, in low-rainfall years there were more tarnished plant bugs, and parasitism rates were doubled, so the two mortality factors were complimentary. Rainfall may also be responsible for differences in lygus numbers between regions. Lygus bugs were five times more abundant in Idaho alfalfa than in New Jersey alfalfa, despite considerably higher parasitism rates in Idaho. Perhaps the lower lygus numbers in New Jersey were caused by the nearly four times higher rainfall there.

Multiple leaders caused by the tarnished plant bug (Lygus rugulipennis) in Picea abies seedlings

Feeding by the tarnished plant bug (Lygus rugulipennis Popp.) has caused severe damage in Norwegian nurseries. Large quantities of seedlings have been removed after sorting. The life cycle of the insect has been well studied and documented. This study was a first attempt to investigate how the seedlings develop after the insect attacks. The first visible sign of damage is the development of multiple terminal buds. Two-year-old containerized seedlings were planted and followed for 4 years. Before planting, the seedlings were sorted into three damage classes: 0, undamaged; I, moderately damaged, up to 10 fully developed buds; and II, severely damaged, 10–20 small buds and no dominant apical bud. The damaged seedlings were somewhat shorter at planting but this difference disappeared with time. The seedlings in the two damage classes differed in their development of multiple shoots. At the end of the 4 year period about 50% of the seedlings in class II and about 20% from class I still had multiple leaders, or lateral stems or side branches that would probably produce spike knots in the future. The sorting routine currently used at the nursery was found to reduce the problem to an acceptable level for seedlings that were planted in the forest.

Epidemiology of fire blight of floricane fruiting red raspberry caused by Erwinia amylovora

Current information on the epidemiology of fire blight of raspberry (Rubus idaeus), caused by Erwinia amylovora, is sparse and based on the assumption of a similarity to fire blight of apple (Malus ×domestica) and pear (Pyrus communis). To test this assumption, epidemiological studies of raspberry fire blight were conducted in controlled environment and in a planting of raspberry selection K81-6, which is highly susceptible to this disease. The bacteria moved down to and overwintered in canes, within 6–10 cm of the soil line, but not at the soil line or in roots. The initial inoculum, responsible for the disease cycle, originated from systemically infected fruiting laterals that develop on floricanes in the spring. These laterals produced bacterial ooze that attracted ants (Tetramorium caespitum) in search of nectar, which then transmitted the inoculum to healthy flowers. Also, tarnished plant bugs (Lygus lineolaris), meadow spittle bugs (Philaenus spumarius), and earwigs (Forficularia auricularia) were shown to vector the pathogen to healthy raspberry leaves and canes through feeding wounds. Infected canes produced copious amounts of bacterial ooze days before other symptoms of fire blight infection became evident. Flowers were infected primarily through the nectaries, and green fruit could be infected only through wound inoculations. Nearly ripe and ripe fruit were not susceptible to infection. The implications of subtle epidemiological differences between apple and raspberry fire blight on disease management strategies are discussed.

Are Lab-cultured Anaphes iole Females Strictly Proovigenic?

Anaphesiole Girault (Hymenoptera: Mymaridae) is a solitary egg parasitoid of Lygus bugs (Heteroptera: Miridae) in North America. Circumstantial evidence suggests that A. iole females are strictly proovigenic. This study was designed to determine if honey-fed A. iole females could in fact mature additional eggs if exposed to hosts for a few days then removed from hosts and held at 25 °C for 0, 3, or 6 days. Contrary to expectation, honey-fed A. iole females matured considerably more eggs when deprived of hosts for 3 or 6 days rather than 0 days. This research suggests that A. iole females are not strictly proovigenic. However, they do have proovigenic tendencies, since most females emerge with at least 71% of their potential fecundity.

The intrinsic toxicity of several neonicotinoids to Lygus lineolaris and Hyaliodes vitripennis, a phytophagous and a predacious mirid

The tarnished plant bug Lygus lineolaris (Palisot de Beauvois) is a key pest of apples in eastern Canada and, currently, chemical control is the only way to manage this pest. Hyaliodes vitripennis (Say) is a univoltine indigenous predacious mirid and an integral part of biological control programs for apples in certain regions of Quebec. In worst-case laboratory conditions, thiamethoxam, thiacloprid and acetamiprid were exceptionally toxic to this predacious mirid. The adults were more susceptible than the nymphs. However, the residual toxicity of these neonicotinoids to L lineolaris in orchards was very short-lived. Because of the short residual toxicity, neonicotinoids should be applied when L lineolaris is at maximum abundance and well before eggs of H vitripennis hatch in late June.

STUDY FOR THE EVALUATION OF DILL (ANETHUM GRAVEOLENS L.) SEEDS QUALITY

In this experiment two different lots of dill seeds (Anethum graveolens L.): lot A - cv. 'Amat' and lot B - cv. 'Lukullus' were evaluated for their characters in terms of their quality. The seeds of the B lot had a lack of embryos caused by lygus bugs (Lygus ssp.), and as a consequence their germination capacity was lower and the number of seeds qualified in the germination test as healthy ungerminated was larger, in comparison with these seed characters of the A lot. Both lots were heavily colonized by fungi, but the percentage of dead seeds was higher in the B lot than in the A one. The seeds in the B lot were previously injured by lygus bugs.

Nickel hyperaccumulation as an elemental defense of Streptanthus polygaloides (Brassicaceae): influence of herbivore feeding mode

No study of a single nickel (Ni) hyperaccumulator species has investigated the impact of hyperaccumulation on herbivores representing a variety of feeding modes. Streptanthus polygaloides plants were grown on high- or low-Ni soils and a series of no-choice and choice feeding experiments was conducted using eight arthropod herbivores. Herbivores used were two leaf-chewing folivores (the grasshopper Melanoplus femurrubrum and the lepidopteran Evergestis rimosalis), a dipteran rhizovore (the cabbage maggot Delia radicum), a xylem-feeder (the spittlebug Philaenus spumarius), two phloem-feeders (the aphid, Lipaphis erysimi and the spidermite Trialeurodes vaporariorum) and two cell-disruptors (the bug Lygus lineolaris and the whitefly Tetranychus urticae). Hyperaccumulated Ni significantly decreased survival of the leaf-chewers and rhizovore, and significantly reduced population growth of the whitefly cell-disruptor. However, vascular tissue-feeding insects were unaffected by hyperaccumulated Ni, as was the bug cell-disruptor. We conclude that Ni can defend against tissue-chewing herbivores but is ineffective against vascular tissue-feeding herbivores. The effects of Ni on cell-disruptors varies, as a result of either variation of insect Ni sensitivity or the location of Ni in S. polygaloides cells and tissues.

Egg load of lab-cultured Anaphes iole and effects of mate presence and exposure time on load depletion

Anaphes iole Girault (Hymenoptera: Mymaridae) is a solitary egg parasitoid of Lygus bugs (Heteroptera: Miridae) in North America. This research considered factors that might impact the egg load of lab-cultured A .iole females, reared from Lygus hesperus Knight egg patches. The following hypotheses were tested: (1) egg load was related to body size and not affected by female age, and (2) egg load depletion was not affected by mate presence and time (in days) that females were exposed to host patches. Initial egg load averaged 48 mature eggs and no immature eggs were detected in the ovarioles of dissected females. Egg load was neither related to body size (hind tibia or forewing length) nor affected significantly by age (0, 1 or 2days old honey-fed females). Mate presence (females with or without males) and exposure time (1, 3 or 5days on the same host patch) had no effect on egg load depletion. Females usually depleted most of their egg load within 24h. From 86 to 92% of females contained less than six mature eggs and no immature eggs after 1, 3 or 5days of exposure to host patches. The results of this study suggest that A. iole females are certainly pro-ovigenic and initial egg load does not correlate with body size or age. Since mated and unmated females deplete most of their egg load in 24h, time-efficient production of progeny may result when ovipositing parasitoids are exposed to suitable hosts for just a few days.

Comparative analysis of the reproductive biology of two Peristenus species (Hymenoptera: Braconidae), biological control agents of Lygus plant bugs (Hemiptera: Miridae)

Abstract Peristenus digoneutis Loan and Peristenus stygicus Loan, parasitoids of the European tarnished plant bug Lygus rugulipennis Poppius, are established in the United States for biological control of native North American Lygus species, and are being considered for deliberate release in Canada. High lifetime fecundity of parasitoids is considered a desirable attribute of biological control agents and therefore, an understanding of parasitoid reproductive biology is required. In the present study, the potential lifetime fecundity of both agents was compared under laboratory conditions to estimate the potential impact of Peristenus species on Lygus . Synovigenic P. digoneutis and P. stygicus females oviposited most actively in the first two weeks of their lifetime, with a maximum average daily oviposition rate after five days. The maximum number of eggs laid per day was 83 eggs for P. stygicus , and 36 eggs for P. digoneutis . P. digoneutis has an average potential lifetime fecundity of 385 ± 35 SE eggs produced over 22 ± 3 SE days. In contrast, P. stygicus females have a 50% higher mean potential lifetime fecundity reaching 782 ± 65 SE eggs over 28 ± 1 SE days. A positive correlation between lifetime fecundity and body size was found only for P. stygicus , and both species showed a significant relationship between lifetime fecundity and oviposition period. The present study demonstrates that the fecundity of P. digoneutis and P. stygicus is considerably higher than previously reported. Based on these findings, P. stygicus appears to be the most effective biological control agent for Lygus lineolaris (Palisot de Beauvois) when only fecundity is taken into consideration.

The relationship between predator density, community composition, and field predation of Colorado potato beetle eggs

Conservation biological control programs seek to increase natural enemy densities through the adoption of more benign farming practices, under the assumption that higher predator densities will lead to more effective pest suppression. However, predator–predator interference may lead to diminishing returns in improved pest control as predator densities increase. We examined the relationship between predator density and predation rates on Colorado potato beetle eggs in production potato fields. These potato fields naturally spanned a 10-fold range in predator density, due to differences in management practices. Periodically through the growing season we simultaneously measured predator densities and subjected sentinel eggs masses to predation, allowing us to correlate predator density and egg predation for each field on each sample date. Egg predation rates were significantly positively correlated with total predator densities, a correlation that was not improved when predator densities were scaled to reflect differences in feeding rates on potato beetle eggs of the constituent predator taxa. There was no correlation between per-capita egg predation rates and predator density, and so no evidence that predator interference increased with increasing predator density. We divided predators into six dominant taxa—dwarf spiders, crab spiders, minute pirate bugs, big-eyed bugs, damsel bugs, and Lygus bugs (together constituting 93% of all predators collected), and a seventh group, “other predators” that included all other, less common, taxa—and examined correlations between all predator combinations and egg predation rates. The highest correlation was between combined densities of the six most common predator taxa, excluding only the “other predators” grouping. This suggests that predators may be largely equivalent in their impact on Colorado potato beetle eggs, and that field scouts might be able to ignore uncommon predator taxa when sampling for natural enemies.

Evaluation of hydrophobic and hydrophilic kaolin particle films for peach crop, arthropod and disease management

Hydrophobic and/or hydrophilic kaolin particle film treatments to peach (Prunus persica (L) Batsch) trees were evaluated for crop and pest management capabilities in six studies from 1997 to 2000. Unsprayed control and standard treatments, the latter consisting of a commercial pesticide program, were included for comparison. Treatments in initial studies were applied via handgun, which resulted in a uniform and heavy deposit of kaolin after the first application. In contrast, treatments in subsequent studies used airblast equipment, which provided a uniform but less dense coverage, even after multiple applications. Results showed that both formulations of kaolin provided control of oriental fruit moth (Grapholita molesta (Busck)), plum curculio (Conotrachelus nenuphar (Herbst)) and Japanese beetle (Popillia japonica Newman) that was comparable with or better than the standard pesticide program. Effective management of late season catfacing insects (tarnished plant bugs Lygus lineolaris (Palisot de Beauvois) and stinkbugs Acrosternum hilare (Say), Euschistus servus (Say), and E tristigmus (Say)) and leafrollers (undetermined species) was also observed, although kaolin applications significantly increased phytophagous mite (Panonychus ulmi (Koch)) levels. In contrast to arthropod management, kaolin failed to control either peach scab (Cladosporium carpophilum (Von Thumen)) or rusty spot (Podosphaera leucotricha (Ell and Ev) ES Salmon) in any of the 4 years of the study. However, hydrophobic kaolin provided effective brown rot (Monilinia fructicola (G Winter) Honey) control when applied via handgun, and partial control when applied via airblast; hydrophilic kaolin failed to provide any control. These results suggest that hydrophobicity and deposit density may be important factors for effective disease management. The application of kaolin significantly delayed fruit maturation, increased fruit size and increased soluble solids relative to the standard. This effect, attributed to a reduction in plant stress, also resulted in increased fruit number and yield on young trees, indicating that an accentuated beneficial response from kaolin applications may be possible.

The relationship between populations of European tarnished plant bug ( Lygus rugulipennis) and crop losses due to fruit malformation in everbearer strawberries

Field experiments in SE England in 1997–1999 were used to determine strawberry crop losses due to the European tarnished plant bug, Lygus rugulipennis. Feeding by the pest on flowers and developing fruits caused malformation of fruits at harvest. A range of pest population densities were generated by different insecticide spray programmes on replicated plots. Relative pest populations were estimated by sampling 40 plants per plot with a beating tray. This method of sampling was shown to have a similar efficiency to suction sampling. A positive correlation was found between the percentage of fruit with moderate or severe malformation and the number of adults plus nymphs of L. rugulipennis. The mean berry weight was also significantly lower in plots with high L. rugulipennis numbers at some sampling dates. A regression analysis of the percentage of moderately and severely malformed fruit against the number of L. rugulipennis was highly significant ( P< 0.001, adjusted R 2=0.34) and had a slope of 0.55, i.e. two Lygus bugs in a beat sample from 40 plants caused approximately 1% of fruits to be malformed. Based on the value of the crop, the cost of insecticide treatment and allowing a safe margin of error, a simple economic spray threshold of one L. rugulipennis per 40 plants is suggested.

Sexual attraction among Lygus (Hemiptera: Miridae) species

Lygus bugs (Hemiptera: Miridae), particularly the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), and Lygus hesperus Knight, are serious pests in North America (Hedlund and Graham 1987). Sex pheromones have been identified in some mirids (Smith et al. 1991; Millar et al. 1997; Millar and Rice 1998) but not in Lygus spp. (Ho and Millar 2002), despite evidence that lygus bug females produce sex pheromones (Scales 1968; Strong et al. 1970; Graham 1987; McLaughlin 1996; Scott and Snodgrass 2000). Graham (1987) found that L. lineolaris and Lygus elisus Van Duzee males were attracted to females of their own and the other species but not to L. hesperus females, whereas L. hesperus males were attracted only to conspecific females. In southwestern British Columbia, Lygus shulli Knight is a major pest in such diverse sites as conifer nurseries and greenhouses (Gillespie et al. 2000). Our objective was to determine whether sexual attraction occurs in L. shulli and whether L. shulli is cross-attracted to females of two other Lygus spp.

Molecular cloning of trypsin-like cDNAs and comparison of proteinase activities in the salivary glands and gut of the tarnished plant bug Lygus lineolaris (Heteroptera: Miridae)

Using specific proteinase inhibitors, we demonstrated that serine proteinases in the tarnished plant bug, Lygus lineolaris, are major proteinases in both salivary glands and gut tissues. Gut proteinases were less sensitive to inhibition than proteinases from the salivary glands. Up to 80% azocaseinase and 90% of BApNAse activities in the salivary glands were inhibited by aprotinin, benzamidine, and PMSF, whereas only 46% azocaseinase and 60% BApNAse activities in the gut were suppressed by benzamidine, leupeptin, and TLCK. The pH optima for azocaseinase activity in salivary glands ranged from 6.2 to 10.6, whereas the pH optima for gut proteinases was acidic for general and alkaline for tryptic proteinases. Zymogram analysis demonstrated that ~26-kDa proteinases from salivary glands were active against both gelatin and casein substrates. Three trypsin-like cDNAs, LlSgP2–4, and one trypsin-like cDNA, L1GtP1, were cloned from salivary glands and gut, respectively. Putative trypsin precursors from all cloned cDNAs contained a signal peptide, activation peptide, and conserved N-termini (IVGG). Other structural features included His, Asp, and Ser residues for the catalytic amino acid triad of serine proteinase active sites, residues for the binding pocket, and four pairs of cysteine residues for disulfide bridges. Deduced trypsin-like proteins from LlSgP2, LlSgP3, and LlGtP1 cDNAs shared 98–99% sequence identity with a previously reported trypsin-like precursor, whereas the trypsin-like protein of LlSgP4 shared only 44% sequence identity with all other trypsin-like proteins, indicating multi-trypsin forms are present in L. lineolaris.

Parasitoid Density and Arena Size Effects on Progeny Production of Anaphes iole Girault (Hymenoptera: Mymaridae)

Anaphes iole Girault is a native, solitary egg parasitoid of Lygus bugs in North America. Ongoing research is considering factors that may lead to efficient mass rearing of A. iole for augmentative biological control. This study examined the effects of A. iole female density and arena size on progeny production. Production increased by a factor of 2.1 as parasitoid density increased from 5 to 10 and from 10 to 20 females per 8 Larena (rearing cage) with a host patch containing from 1,500 to 2,000 eggs of Lygus hesperus Knight (Heteroptera: Miridae). Sex ratios of mature progeny did not differ significantly between parasitoid densities of 10 versus 20 females. Arena size (≈1, 2, 4, or 8 L cages) had no effect on progeny production when 20 females were confined to the same cage. This research suggests that little or no measurable interference will occur between ovipositing A. iole females on shared host patches and cage size can be varied to increase rearing capacity.

The effects of trichlorfon and deltamethrin on alfalfa plant bug and lygus bug (Heteroptera: Miridae) populations in alfalfa grown in Canada

Plant bugs (Heteroptera: Miridae), chiefly lygus bugs ( Lygus spp.) and alfalfa plant bug ( Adelphocoris lineolatus (Goeze) (APB)), are the main insect pests of alfalfa seed production in Canada. A 3-year study was conducted in small plots of alfalfa at Melfort, Saskatchewan, Canada, to determine the effectiveness of trichlorfon at a single rate and deltamethrin at several rates for controlling these pests. Trichlorfon effectively controlled APB each year and both trichlorfon and deltamethrin controlled Lygus spp. each year. Consistent control of APB populations was not achieved with deltamethrin; the insecticide controlled APB in the first year of the study, but was effective for only 2 weeks in the second year, and it did not reduce APB numbers below economic thresholds in the last year. In 1 year, numbers of beneficial arthropods were higher in control and trichlorfon plots than in deltamethrin plots. Alfalfa seed yields combined over 3 years were increased by trichlorfon at 560 g a.i./ha and by deltamethrin at 12.4, 14.8, and 17.3 g a.i./ha. Based on these data, despite occupying similar niches in alfalfa, lygus bugs and APBs have different levels of susceptibility to deltamethrin; therefore, the chemical should not be recommended for control of APB in seed alfalfa fields.

Cytochrome P450 CYP6X1 cDNAs and mRNA expression levels in three strains of the tarnished plant bug Lygus lineolaris (Heteroptera: Miridae) having different susceptibilities to pyrethroid insecticide.

Three cDNAs, cloned from both pyrethroid-susceptible and -resistant strains of Lygus lineolaris, contained a 1548 nucleotide open reading frame encoding a 516 amino acid residue protein. Predicted cytochrome P450s from cDNAs were classified as the first three new members of subfamily CYP6X, CYP6X1v1 for a susceptible strain and CYP6X1v2 and CYP6X1v3 for two resistant strains. Putative cytochrome P450 CYP6X1s from L. lineolaris were highly similar (up to 42% amino acid sequence identity) to several insect CYP6s that are responsible for reduced sensitivity to pyrethroid insecticides. A total of twenty-six nucleotide substitutions were revealed between cDNAs of susceptible and resistant strains. Two nucleotide substitutions resulted in amino acid changes, Asp373 to Ala373 and Ser487 to Ala487, between susceptible and resistant strains. The resistant laboratory strain contained 2.1-fold higher cytochrome P450 mRNA per microgram total RNA than the susceptible laboratory strain. Topical treatment with 10 ng permethrin elevated cytochrome P450 mRNA levels by approximately 2-fold. The results of this study indicated that cytochrome P450 gene mutation, coupled with up-regulation, was present only in the pyrethroid resistant strains, and was possibly related to resistance development in the tarnished plant bug.

Toxicity of field-weathered insecticide residues to Anaphes iole (Hymenoptera: Mymaridae), an egg parasitoid of Lygus lineolaris (Heteroptera: Miridae), and implications for inundative biological control in cotton

Anaphes iole Girault is an egg parasitoid that has potential as an inundative biological control agent for the tarnished plant bug Lygus lineolaris (Palisot de Beauvois) in cotton in the midsouth USA. Our research addressed survival of A. iole wasps exposed to field-weathered residues of insecticides important to cotton production in the region. Our objectives were to identify insecticides with decay profiles that might be compatible with augmentative releases of A. iole in cotton. Survival of female wasps exposed to field-weathered residues on cotton leaves was determined at 0, 2, 4, 8, 16, 23, and 30 days after treatment with field rates of nine compounds. Immediately after treatment, residues of most insecticides (acephate, cyfluthrin, λ-cyhalothrin, imidacloprid, thiamethoxam, spinosad, fipronil, and oxamyl) resulted in <3% survival. Indoxacarb was the exception with about 30% survival at this time. Survival of wasps exposed to oxamyl, imidacloprid, indoxacarb, and acephate increased considerably during the first week after treatment. Upper limits of 95% CI values for ST 50 estimates (days for 50% survival) were ⩽5 days for these insecticides. Survivorship of wasps exposed to λ-cyhalothrin and thiamethoxam was intermediate (95% CI values between 5 and 11 days). Of the insecticides tested, residues of cyfluthrin, fipronil, and spinosad were most deleterious to A. iole (95% CI values > 11 days). Precipitation and wind speed during the study period were less than 30-year averages; thus, under typical weather conditions insecticides might decay more rapidly than observed in this study. Our results suggest that while most insecticides tested exhibited high acute toxicity to A. iole wasps, residues of several compounds decayed rapidly enough to show promise in an augmentative release program.