Colorado Potato Beetle Egg Masses Research Articles

Wildflower plantings in commercial agroecosystems promote generalist predators of Colorado potato beetle

Wildflower plantings in agroecosystems can support arthropod predators, and may have the potential to increase conservation biological control of pest species in nearby crops. Colorado potato beetle (CPB) is a significant defoliator of potato that is resistant to many forms of management. Promoting natural enemies of CPB by establishing perennial wildflower plantings in field margins may provide a measure of control for this pest. We examined the impacts of floral plantings on the abundance of known CPB predators, predation of CPB egg masses, and CPB populations in a commercial agroecosystem. Floral plantings increased the abundance of CPB predators, but did not significantly increase the rate of predation of sentinel CPB egg masses within field margins. Within nearby potato fields, predator abundance and predation rates on CPB eggs were unaffected by the presence of flowers. Colorado potato beetle abundance in potato fields was also not impacted by floral plantings. However, floral margins may provide improved overwintering opportunities for CPB, and further investigation is needed. Perennial wildflower plantings show potential for attracting predators that prey on CPB, but these benefits do not extend into nearby potato crops.

Oviposition of the Colorado potato beetle (Leptinotarsa decemlineata) and natural predation on its egg masses in Bt-expressing fields

Generalist predators are relevant natural enemies of the Colorado potato beetle (CPB) in Europe. In fields of insect resistant genetically modified plants (GMPs), predators could be exposed to toxins either directly (e.g., via pollen), or indirectly through feeding on herbivorous prey. Hence, they represent an important functional group to consider when studying environmental impacts of GMPs. CPB females show a ‘bet-hedging’ strategy in spatial and temporal distribution of eggs, through which the species tries to minimize the risks of progeny loss due to adverse conditions. Experimental fields of GM eggplants expressing Cry3Bb toxin and potatoes expressing Cry1Ab toxin were set up. CPB egg masses were counted on naturally infested plants at four time points during the field season of each crop. To assess predation, newly deposited egg masses were marked at the same dates. Daily visual observations were conducted recording the numbers of intact or preyed eggs and neonate larvae. In both cases, oviposition was similar between GM and control plots, as the number of egg masses per plant and the number of eggs per mass did not differ significantly between treatments. A statistical analysis of the spatial distribution of egg masses revealed a similar aggregation in the potato field, whereas in the eggplant field, the variance of the number of egg masses per plant was smaller than expected in GMP plots. The predation rate was similar between treatments. These results suggest that the ecological function of natural predation on CPB eggs in GM plots was not impaired.

Pathogenicity of six isolates of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina, Hyphomycetes) to Perillus bioculatus (F) (Hem., Pentatomidae)

Abstract: The two‐spotted stink bug, Perillus bioculatus (F) (Hem., Pentatomidae) is considered an important predator of Colorado potato beetle egg masses and small larvae. The susceptibility of P. bioculatus second instar nymphs to six isolates of Beauveria bassiana (Balsamo) Vuillemin, which are highly pathogenic to Colorado potato beetle, was tested in the laboratory. Five isolates were highly pathogenic and caused more than 77% mortality after 8 days at a concentration of 106 conidia/ml. However, isolate IPP46 showed low pathogenicity and caused only 11% mortality of nymphs. The pathogenicity of isolates was independent of their host, source or country of origin. Isolate IPP46 was tested at six different concentrations. A linear relationship between the concentration of B. bassiana and the mortality of nymphs was observed. The 50% lethal concentration (LC50) value was 3.4 × 107 conidia/ml. The LT50 decreased with increase of conidia concentration used. The present results suggest that isolate IPP46 has good potential as a biological control agent within an integrated pest management programme.

Evaluating Edovum puttleri Grissell and Podisus maculiventris (Say) for Augmentative Biological Control of Colorado Potato Beetle in Tomatoes

Multiple releases of Edovum puttleri Grissell (Hymenoptera: Eulophidae) and Podisus maculiventris (Say) (Heteroptera: Pentatomidae) resulted in increased parasitism and predation rates of eggs of Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), in small plots of staked tomatoes grown in plastic or hairy vetch mulch. No consistent effect of the mulch on CPB infestations was found over the years of the study. No parasitism by E. puttleri occurred in 1995, while parasitism ranged from 0 to 30.6% per sample date in 1997. P. maculiventris nymphs were found at higher densities in release plots and readily attacked CPB egg masses. Despite the ability of both beneficials to search the structurally complex plant and find the pest, the cost of maintaining release rates that were high enough to achieve significant control of the pest would be prohibitive on a larger scale.

Location and abundance of adult Colorado potato beetles (Coleoptera: Chrysomelidae) following potato harvest

Colorado potato beetle, Leptinotarsa decemlineata (Say), population biology was investigated after Irish potatoes, Solanum tuberosum (L.), were harvested in eastern North Carolina. The abundance of adult Colorado potato beetles following potato harvest was estimated by taking more than 450 visual transects in 45 commercial potato fields in July and August, 1993 and 1994. Few second- and third-generation Colorado potato beetle egg masses and larvae, volunteer potato plants and wild hosts such as horsenettle, S. carolinense L., were encountered, suggesting that Colorado potato beetle generations produced after potatoes are harvested in June and early July do not contribute significantly to the overall overwintering population. Location and abundance of overwintering adult Colorado potato beetles within the soil in fields previously planted in potato were determined. Densities of overwintering adults in soil along field edges were greater than those within fields prior to emergence in the spring, suggesting that adults moved toward field edges to overwinter. However, given that the area within potato fields was much greater than the area along field edges, the estimated total number of overwintering adults within fields was greater than along the edges. In light of these results, tillage at different times between crop production seasons was evaluated for its effect on overwintering Colorado potato beetle survival, but was found to have little effect.

Facilitated predation through interaction between life stages in the stinkbug predatorperillus bioculatus (Hemiptera: Pentatomidae)

Competitive interactions in arthropod predators are well-known, but positive interactions have received less attention. The two-spotted stinkbugPerillus bioculatus often feeds gregariously on leaf beetle larvae and caterpillar prey. Consequences of prey sharing amongP. bioculatus conspecifics of dissimilar size (instar) was studied using Colorado potato beetle (CPB) prey. Rearing second-instar (N2) nymphs ofP. bioculatus with an N5 conspecific facilitated early feeding on L4 CPB larvae (a difficult prey to handle by N2 nymphs but not by N5’s), thus increasing survival and accelerating development. One in every 20 cases ofP. bioculatus foraging in the field was accounted for by pairs or small groups of mostly feeding individuals. CPB egg masses and L4’s represented a disproportionate number of cases of aggregated feeding byP. bioculatus, compared to feeding singly. Small CPB larvae decreased in the diet of aggregated stinkbugs compared to L4 larvae and egg masses, suggesting that sharing these prey may be favorable or unavoidable. In a field test measuring residence/survival of N2’s limited to L4 prey, the N2’s rate of residence/survival increased significantly when large nymphs acting as food providers were also present. The function of communal feeding inP. bioculatus is discussed, as well as the potential for greater impact on prey density that may be expected from tolerance to opportunistic feeding by conspecifics in slightly gregarious predators.

BIOLOGICAL CONTROL OF THE COLORADO POTATO BEETLE LEPTINOTARSA DECEMLINEATA (COLEOPTERA: CHRYSOMELIDAE) IN QUEBEC BY AUGMENTATIVE RELEASES OF THE TWO-SPOTTED STINKBUG PERILLUS BIOCULATUS (HEMIPTERA: PENTATOMIDAE)

AbstractField plot tests during two seasons show that augmentative releases of Perillus bioculatus can control first-generation eggs and larvae of the Colorado potato beetle (CPB) under Quebec short-season conditions. Stinkbugs mass-reared on CPB were introduced manually as 2nd- and 3rd-stage nymphs during spring oviposition of the beetle at densities of one nymph per 50–225 CPB eggs recruited per plant, in 0.025-ha plots. Sampling at intervals of 1–3 days measured predator establishment, CPB egg and larval mortality, and foliage protection level. Direct observations were used to document predator-prey relationships and to determine weather conditions favourable to P. bioculatus.In the 1 st-year test, with predators released over all plants within plots, CPB control was compared among: (1) stinkbugs alone, (2) the bioinsecticide Bacillus thuringiensis (BT) as Trident™, (3) a combination of both control alternatives, and (4) no protection against the CPB. BT and stinkbugs, both alone and in combination, produced significant control as measured by percentage reductions in prepupal drop to the ground, new adult emergence, and foliage protection. Only treatments involving P. bioculatus reduced CPB egg eclosion which was the key control factor; it is strongly correlated with overall control level.In the 2nd-year test, predators were released in a central area comprising only 25% of all plants within plots. Predator and CPB egg mass densities were manipulated to produce predator: prey ratios of 0:1, 0:2, 1.5:2, 1.5:1, 3:2, and 3:1, representing average ratios of 0, 1.5,or 3 P. bioculatus per plant, and 1 or 2 CPB egg masses per plant at release time. As expected, central release produced complex interactions between control, and predator and prey densities. High beetle density slowed predator emigration from the centre, more so at low predator density than at high predator density. Predators moved more quickly within the same row than across rows. CPB eggs were destroyed in large numbers in both years but in 1993, final control correlated with larval rather than egg predation. A maximum 80% reduction in prepupal drop to the ground was obtained at the 3:1 predator:prey ratio (1 P. bioculatus:95 CPB eggs recruited per plant).The results prove the efficacy of P. bioculatus for biological control of first-generation L. decemlineata populations, at densities resulting in approximately 300 eggs laid per plant during spring oviposition in the study area. Despite low natural populations of P. bioculatus and unclear prospects for commercial availability at reasonable cost, it is evident that stinkbug releases have potential as a non-chemical control measure within an IPM program in Quebec potato production.

Bacillus thuringiensis ssp. tenebrionis Sprays Affect Hatching of Colorado Potato Beetle (Coleoptera: Chrysomelidae) Eggs and Subsequent Larval Dispersal

Laboratory and field experiments were conducted to evaluate the effect of Bacillus thuringiensis subsp. tenebrionis (Novodor Insecticide, Novo Nordisk, Danbury, CT) sprays on hatching of Colorado potato beetle, Leptinotarsa decemlineata (Say), eggs and subsequent dispersal of larvae. In laboratory treatments, nearly all egg masses hatch after treatments of 0, 0.2, 1.0, 5.0, and 10.0% (vol:vol) Novodor. Although all larvae from egg masses treated with only water dispersed within 4 d of hatch, larval dispersal and subsequent survival was < 50% in the 0.04% (vol:vol) Novodor treatment, 4% in the 1 and 5% (vol:vol) Novodor treatments, and 0% in the highest Novodor treatment. In the field, freshly deposited egg masses on eggplant were marked; spray applications of Novodor at rates of 0, 1.17,2.34,4.68, and 7.02 liters/ha were applied; and the marked egg masses were monitored over the following 6 d for hatching and dispersal of larvae. Percentage egg masses hatching and dispersal of larvae from the egg mass (survival) declined as the rate of Novodor increased. Plots treated with the high rate (7.02 liters/ha) of Novodor had only 5% dispersal of larvae from treated eggs. These data show that B. thuringiensis subsp. tenebrionis applications on Colorado potato beetle egg masses can be of benefit to growers by killing larvae as they emerge from the egg, thus reducing dispersal of larvae from the egg mass. Implications of this pesticide activity for pest management strategies are discussed.

Inundative Release of Predatory Stink Bugs for Control of Colorado Potato Beetle

Release of Periflus bioculatus (F.) (Hemiptera: Pentatomidae) nymphs at either 1.6/row-m (0.5/row-ft) or 9.8/row-m (3/row-ft) significantly reduced the number of both small and large larvae of the Colorado potato beetle in small plots. The number of Colorado potato beetle egg masses was significantly reduced by the high release rate as well as by the low rate in combination with a reduced spray schedule of Bacillus thuringiensis var. tenebrionis Berliner. Potato plant defoliation was significantly reduced by the high release rate. Three systemic soil insecticides (disulfoton, phorate, and aldicarb) caused significant mortality of P. bioculatus nymphs exposed to potato foliage 11 weeks after soil application. Four foliar insecticides had no effect on P. bioculatus nymphs exposed to recently sprayed foliage.

Control of Colorado Potato Beetle, 1992

Abstract Potatoes were planted 14 May at the Research Farm of the Red River Valley Potato Growers Association, Grand Forks, ND. Plots were 4 rows wide, 18.9 m (62 ft) long, with 96 cm (38 in) spacing between rows and 30 m (12 in) between plants. Plots were arranged in 6 tiers of 34 plots each. Plots were separated laterally by two in planted rows (1.9 m) and tiers were separated by 7.6 m. Borders of plots were maintained weed-free by cultivation. The planting was divided into three experiments each consisting of a completely randomized plot design with 4 replications. Experiment 1 was to evaluate various rates and formulations of Bacillus thuringiensis (B.t) insecticides. Experiment 2 was to evaluate several synthetic organic insecticides and Cryolite. Experiment 3 was to evaluate two neem-based insecticides (ATI-720 and Margosan-O) alone or in combination with other insecticides. Plots were scouted daily for Colorado potato beetle egg masses beginning 11 Jun. When egg masses were found these were flagged and checked daily for hatch. Hatch of flagged eggs reached 25% on 22 Jun. Sprays were applied in all three experiments on 24 Jun, 7 Jul, and 15 Jul. Insecticidal sprays were applied using a tractor-mounted boom sprayer, with a single Teejet nozzle over each row. Sprays were applied in 150 liters of water/ha (40 gal/acre) at 275 kPa (40 psi).

Diurnal Timing of Ovipositional Activities of Edovum puttleri (Hymenoptera: Eulophidae), an Egg Parasitoid of Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Visits by Edovum puttleri Grissell to Colorado potato beetle egg masses on potato plants in field cages were most frequent between 1100 and 1600 hours, 6–11 h after sunrise. In the laboratory at 26 ± l°C, 16:8 (L:D) photoperiod, peak oviposition occurred during the 4-h period between 1400 and 1800 hours, 8–12 h after the lights were turned on. No eggs were laid during the scotophase.

Potential for the biological control ofLeptinotarsa decemlineata [Col.: Chrysomelidae] by the egg parasite,Edovum puttleri [Hym.: Eulophidae] in Maryland, 1981–84

The biological control potential ofEdovum puttleri Grissell, an exotic egg parasite ofLeptinotarsa decemlineata (Say), was examined in experimental potato plots. The parasite does not overwinter in Maryland, but through annual inoculative releases it consistently parasitized Colorado potato beetle (CPB) egg masses throughout the season. Approximately 50% of all egg masses collected were parasitized and maximum parasitism byE. puttleri occurred in egg masses produced by first generation adults.Edovum puttleri reproduced and maintained itself in potato plots for 15 weeks. The random sampling of CPB egg masses to evaluate the parasite in the field is described.

Relative Toxicities of Insecticides to Entomophagous Species and Colorado Potato Beetle Larvae, 1983

Abstract Potatoes were planted with 12 inch (30.48 cm) spacing in 50 ft (15.38 m) rows 36 inch (0.914 meters) apart on 25 Apr near Prairie Home, MO. Insecticides were applied to 12 ft (3.66 meters) sections of rows replicated 4 times in a randomized complete block design, with the 5 treatments applied to alternate rows with an untreated row as a butter between each treatment row. The sprays were applied on 16 Jun with a 2 gal (7.57 liter) hand held compressed-air sprayer calibrated to deliver 100 gal/acre (935.27 1/ha) 30 psi (2109 g/cm2). Just prior to spray application, 1 laboratory reared Colorado Potato Beetle (CPB) egg mass was stapled to the underside of the first large leaf down from the terminal of 2 plants in each replicate. Ten adult E. puttleri for 3rd instar P. maculventris were released on the plant to which the CPB eggs had been attached in each replicate ca. 3 h post application. The released CBP eggs were recovered 2 days post spray to assess effects of the compounds tested on predation, and/or host feeding and parasitization by E. puttleri. Evaluation criteria were direct counts of CPB larvae and entomophagous species/8 plants, parasitization and host feeding by E. puttleri parasitization and predation of the CPB egg masses recovered, and observed instances of predation.

Irish Potato, Potato Insect Control, Pasquotank County, 1979

Abstract 'Superior' Irish potatoes were planted on Mar 27, near Elizabeth City, NC. Single-row plots 25-ft long were replicated 4 times in a randomized complete block design with 5-ft alleys between replications. Granular treatments were applied by hand-held shaker jars and incorporated just before planting. Foliar applications were applied at the rate equivalent to 100 gallons of water per acre using a 2.5-gallon CO2 pressurized hand sprayer operated at 40 psi and equipped with a hollow cone nozzle. Colorado potato beetle egg masses were placed in plots on Apr 25. Pretreatment larave counts were made on 2 plants/plot on May 2 followed by a foliar spray application. Posttreatment counts were made on May 9 followed by a foliar spray application. Another foliar spray application was made on May 24. Stand counts and number of plants in fested with European corn borer were made on May 30. European corn borer entry points were noted on Jun 4 . Yield data was obtained on Jun 20.