Solanum berthaultii Hawkes affects the digestive system,fat body and ovaries of the Colorado potato beetle

Ovarian development and fecundity of Colorado potato beetles reared on the resistant potato species,Solanum berthaultii were reduced compared to females reared on the susceptible potato,S. tuberosum. Striking changes in the appearance of the digestive tract and large quantities of undigested plant material in the midgut of females reared onS. berthaultii suggest that ovarian development might be impaired by poor nutritional quality ofS. berthaultii foliage. Alternatively, enlargement of the midgut by undigested plant material might physically limit ovarian development and subsequent fecundity. These results suggest that a major impact ofS. berthaultii on CPB performance occurs in the physiology of digestion and reproduction.     

Feeding behavior and survival of Colorado potato beetle,Leptinotarsa decemlineata (Say), larvae onSolanum berthaultii Hawkes and an F6 S. tuberosum L. XS. berthaultii hybrid

Newly hatchedLeptinotarsa decemlineata larvae were less likely to initiate feeding onSolanum berthaultii than onS. tuberosum. Among larvae that fed there was no difference in the time to initiation of feeding; however, the duration of the initial feeding bout was less onS. berthaultii than onS. tuberosum. Larvae spent less time feeding and more time walking onS. berthaultii than onS. tuberosum. All larvae caged onS. tuberosum fed within 24 hours, but larvae were less likely to feed on a F₆ S. tuberosum XS. berthaultii hybrid and least likely to feed onS. berthaultii. Lack of feeding during the first 24 h was highly correlated with mortality at 72 h. Whether or not larvae feed within the first five minutes of being placed on a leaflet is a reliable predictor of larval mortality at 72 h and is a useful test for determining the susceptibility of plants to feeding byL. decemlineata. The amount of trichome exudate accumulated on the tarsi over a 72 h period is correlated with resistance. Resistance ofS. berthaultii to neonateL. decemlineata is characterized by a refusal to initiate feeding and a reduced feeding rate by larvae that do feed.     

Inheritance of glandular trichomes in crosses withSolanum berthaultii

The inheritance of trichome density and droplet size was investigated in diploid and tetraploid crosses. In haploidTuberosum ×Solanum berthaultii and (S.phureja ×haploid Tuberosum) × S.berthaultii crosses, droplet size on type B trichomes was small or droplets were lacking on F₁ hybrids. Parental phenotypes were recovered in the F₂ and backcross generations. Trichome density was more variable within a clone that was droplet size. Density of both type A and type B trichomes appears to be under the control of small numbers of genes, as parental phenotypes were recovered in the F₂ and backcross generations. The variation observed for each of the three traits studied could not be explained by hypotheses based on the segregation of one or two loci. The insect resistance ofSolanum berthaultii appears to be due to the interaction of several chemical and physical factors, thus potato breeders should handle it as a quantitatively inherited trait.     

Phenolic constituents of glandular trichomes onSolanum berthaultii andS. polyadenium

Phenolic compounds in Type A glandular trichomes of two insectresistant potato species were separated and identified using a combination of high pressure liquid chromatography (HPLC), UV-visible spectrometry, and¹H proton nuclear magnetic resonance (NMR) procedures. Type A trichomes ofSolanum berthaultii andS. polyadenium contained a phenolic compound tentatively identified as the glucose ester of p-hydroxyphenylpropionic acid. Its presence in trichomes of both species suggests that this compound may play a major role in formation of the brownish, insect entrapping exudate characteristic of trichome-mediated insect resistance in these species. Chlorogenic acid, a major phenolic constituent of Type A trichomes ofSolanum polyadenium was not detected in trichomes of 5.berthaultii. The exclusive presence of chlorogenic acid in trichome exudates ofS. polyadenium may be responsible, at least in part, for the greater levels of insect entrapment by this species, compared with that ofS. berthaultii.     

A survey of potato species for resistance to the mitePolyphagotarsonemus latus,with particular reference to the protection ofSolanum berthaultii andS. tarijense by glandular hairs

Summary Resistance to damage by the mitePolyphagotarsonemus latus (Banks) occurred inSolanum polyadenium Greenm. and in seedlines ofS. tarijense Hawkes andS. berthaultii Hawkes which had foliar hairs with a sticky tip. On secondment from Rothamsted Experimental Station, Harpenden, Herts., England.     

Immunodetection of Polyphenol oxidase in glandular trichomes ofS. berthaultii,S. tuberosum and their hybrids

Type A glandular trichomes confer insect resistance to the wild potato,S. berthaultii Hawkes by oxidatively polymerizing their contents upon breakage, resulting in insect entrapment. Polyphenol oxidase (PPO) is responsible for the oxidative polymerization of Type A glandular trichome exudate.S. tuberosum L. trichomes possess low amounts of PPO and lack the ability to either polymerize their contents or entrap insects. Polyclonal antibodies raised against purifiedS. berthaultii glandular trichome PPO were used to develop an enzyme-linked immunosorbent assay (ELISA) to quantify PPO content ofS. berthaultii, S tuberosum, and hybrid type A glandular trichomes. The PPO ELISA and immunoblots were used to quantify PPO expression as a function of leaf development and genetic background. PPO accumulates to its maximal levels in trichomes prior to completion of leaflet expansion. In advanced breeding generations, trichome PPO is expressed at levels varying from that found inS. tuberosum to that found inS. berthaultii. By serving as an initial screen for trichome PPO, this ELISA may be useful to assist rapid introgression of this insect resistance trait into adaptedS. tuberosum backgrounds.     

Control of the Colorado potato beetle withBacillus thuringiensis varietyThuringiensis

Field tests were conducted to determine the effectiveness of an experimental preparation ofBacillus thuringiensis var.thuringiensis against Colorado potato beetle infestations on potatoes and tomatoes. Applications were made weekly with a tractor-towed commercial sprayer at the rates of either 473, 946, or 2,838 ml. ofB.t.t. in 378.41 of water per 0.4 hectare. Significant reductions were observed in treated plots of all stages of the beetle. All untreated plants were completely defoliated by the end of the test due to beetle feeding. No significant differences were observed among the different treatment levels.     

Control of the Colorado potato beetle by treatment of potato seed pieces

Dusting or soaking freshly cut potato seed pieces in systemic insecticides controlled the first generation larvae of the Colorado potato beetle at Yakima, Washington in 1970. The most promising materials were tested again in a larger experiment in 1971. Fifty days after treatment, Bay 37344 (4-(methylthio)-3,5,xylyl methylcarbamate), Dasanit^® (O,O-diethyl-O-[p-(methylsulfinyl) phenyl] phosphorothioate), Shell SD 17250 (N-(methylcarbamoyl)oxy]thioacetimidic acid ester with 3-mercaptopropionitrile) and Plant Protection PP062 (dimethylamino)-4,5,6-dimethyl pyrimidinyl dimethylcarbamate) all gave significantly better control of the larvae than methomyl, azinphosmethyl and menazon.     

Suspension velocity of the Colorado potato beetle in free fall

The suspension velocity of the Colorado potato beetle was determined for four stages of its life cycle. Suspension velocities measured using an experimental video technique agreed reasonably well with theoretical values. Suspension velocities for the adults, fourth, third, and second instars were 9.4, 9.5, 7.3, and 5.9 m/sec, respectively. Recent experimental results suggest that a large percentage of adults and large larvae of the Colorado potato beetle are missed during a single pass of commercial field scale vacuum insect collectors. The relatively low suspension velocity of free falling small larvae explain, at least in part, why only 3% of the small larvae fell to the ground.     

Glycoalkaloids and resistance to the Colorado potato beetle inSolanum chacoense Bitter

Resistance of 20 F₂ Solarium chacoense Bitter clones to the Colorado potato beetle,Leptinotarsa decemlineata (Say), was measured in a field test. Levels of total glycoalkaloids (TGA) and composición of the glycoalkaloid mixtures in foliage of the clones were also determined. Clones with either commersonine or dehydrocommersonine as the major foliar glycoalkaloid were significantly more resistant (lower damage ratings, fewer larvae and adult insects) than clones with solanine and chaconine. Damage ratings were negatively correlated (r = -0.67, p = 0.01) with foliar TGA levels. The results indicate that the types of glycoalkaloids present in the foliage ofS. chacoense may be as important as the level of TGA in limiting damage and numbers of insects.     

Field selection for esfenvalerate resistance by the Colorado potato beetle

Five insecticide application regimes were evaluated for two years to determine their influence on the development of esfenvalerate resistance by the Colorado potato beetle (CPB),Leptinotarsa decemlineata (Say). These included sequential applications of esfenvalerate; two alternated uses of esfenvalerate, azinphosmethyl, endosulfan, oxamyl, andBacillus thuringiensis or cryolite; an IPM program; and one early season esfenvalerate application. Both CPB adults and first instars were tested for esfenvalerate resistance before and after insecticide applications. The LC₅₀’s in the early 1992 season were correlated with values in the late 1991 season. However, over the winter, esfenvalerate resistance of CPB adults decreased, but was relatively stable for first instars. Esfenvalerate LC₅₀’s late in the season were generally higher than values early in the season. Increases in esfenvalerate LC₅₀’s were correlated with the number of esfenvalerate applications made in these fields during the growing season, with the greatest increase found in the sequential esfenvalerate treatment.     

Survey of Colorado potato beetle insecticide resistance in Idaho

Colorado potato beetle populations from Idaho were surveyed for resistance to carbofuran, endosulfan, esfenvalerate, and phosmet in a discriminating concentation bioassay of spring emergent and first generation adults. No carbofuran or endosulfan resistance was detected in 29 populations surveyed. Esfenvalerate and phosmet resistance was detected in all potato growing areas of the state. For the same populations, spring adults were more sensitive to phosmet than were first generation adults. Susceptible populations were found in the same regions as resistant populations.     

Management of the Colorado potato beetle using the entomogenous fungusBeauveria bassiana

Small field plots of Katahdin potatoes on Long Island, NY were treated 6 times in 1980 for control of Colorado potato beetle (CPB)Leptinotarsa decemlineata (Say), Coleoptera: Chrysomelidae, using either the entomogenous fungusBeauveria bassiana (Balsamo) Vuill. (Bb) at 5x 10¹³ colony forming units/ha or fenvalerate at 0.227 kg active ingredient/ha. No significant differences were found between Bb and fenvalerate treatments in egg mass size and viability or in the total foliage consumed by first generation CPBs. First generation CPB larval populations were significantly higher in Bb plots. Oviposition by first generation adults and second generation beetle populations were higher in fenvalerate plots. Average yield was 29.4 metric tons/ha in fenvalerate plots and 24.6 metric tons/ha in Bb plots (a 16% reduction), but nearby untreated plots were completely defoliated by July 24 and yielded <7 metric tons/ha (> 60% reduction).     

Variation in sucrose esters from the type B glandular trichomes of certain wild potato species

Accessions of four insect resistant wild potato species (i.e., S. berthaultii,S. neocardenasii, S. polyadenium andS. tarijense) were examined for the presence of glandular trichomes and any associated sucrose esters. Of the thirty accessions examined, ten proved positive for the presence of type B glandular trichomes and accompanying sucrose esters. Three distinct complexes of sucrose esters were identified (i.e., 3,4,6-tri-0, 3,3′,4,6-tetra-0-, and 2,3,3′,4-tetra-0-acylated) and the acyl substituents were found to vary significantly within each complex. Possible rationales for the observed distribution of the sucrose esters within the species are discussed and comparative data from some non-tuberousSolanums and other genera of the Solanaceae family are presented.     

Influence of Colorado potato beetle sample counts and plant defoliation on potato tuber production

Field experiments were designed to subject Superior potato plants to various levels of defoliation by the Colorado potato beetle (CPB)Leptinotarsa decemlineata (Say), Coleoptera: Chrysomelidae. Defoliation occurred during each of five consecutive plant growth periods and CPB population, plant leaf area, and tuber weight data were recorded for each period. A visual defoliation rating scheme provided an accurate estimate of actual potato plant leaf area of defoliated plants. Data generated from regression analysis demonstrated a significant dependence of leaf area on CPB numbers per plant during some plant growth periods, but numbers of CPB accounted for very little of the total variation in tuber weight. Plant leaf area was the most important independent variable in the tuber weight regression model.     

The extraction and partial purification of a rhamnosidase from Colorado potato beetle larvae (Leptinotarsa decemlineata (Say))

An enzyme which hydrolyzed a terminal rhamnose moiety from α-chaconine was extracted and partially purified from Colorado potato beetle (CPB) (Leptinotarsa decemlineata) larvae. This ammonium sulfate precipitated enzyme fraction resulted in nearly 97% metabolism of α-chaconine after a 144 hour incubation period at 42 C as determined by high performance liquid Chromatographic (HPLC) analysis. Approximately 81% of the metabolized α-chaconine was detected asβ ₂-chaconine. The isolated enzyme fraction from CPB larvae exhibited no metabolism of α-solanine. Metabolism was also followed over time by thin layer chromatography (tlc).     

Bacillus thuringiensis a potential control agent for the Colorado potato beetle

In laboratory tests conducted to determine the effectiveness of the exotoxin ofBacillus thuringiensis against the Colorado potato beetle,Leptinotarsa decemlineata (Say), applications sprayed on tomato foliage at dilutions ranging from 10^?1 through 10^?4 killed 90% of the 1st and 2nd stage beetle larvae. As the dosage decreased, the time to achieve this level of mortality increased from 4 to 9 days. Adult beetles were not killed by these treatments; however they did cease feeding. In field tests, the highest dosages ofB. t. sprayed on either tomato or potato plants provided adequate or nearly complete protection when applied weekly. Young larvae that ingested sub-lethal doses developed into adults with atrophied mouthparts and antennae, transformations of the paired parts of the labial palps into an unpaired part, the appearance of a tarsal-like claw on a palp, and malformation of the cranial sclerities.     

Performance of Colorado potato beetle larvae,Leptinotarsa decemlineata (Say), reared on synthetic diets supplemented withSolanum glycoalkaloids

Glycoalkaloids are a class of secondary compounds (nitrogenous, steroidal glycosides), ubiquitously distributed throughout the Solanaceae. Numerous studies (in planta) have shown that certain glycoalkaloids, e.g., α-tomatine, solanocardenine, and leptine, have a negative impact on performance of the Colorado potato beetle,Leptinotarsa decemlineata (Say). However, the presence of other secondary compounds, as well as the nutritional status of the plants used, are additional variables in such experiments. By rearing Colorado potato beetle, from egg to prepupal stage, on a synthetic diet supplemented with the glycoalkaloids α-tomatine, α-chaconine, α-solanine, leptine I and the steroidal aglycone solanidine, we have been able to further establish the effects (ex planta) of these compounds on the Colorado potato beetle. Leptine I displayed a dose-dependent negative activity against the Colorado potato beetle (as measured by larval weight gain and tune to molt), when assayed at 0.31, 0.62 and 1.23 mM concentrations; however, by the fourth stadium no effect was found. When Colorado potato beetle were fed a higher concentration of leptine I (2.4 mM), there was a sustained effect in all stadia. At 2.4 mM, leptine I displayed a greater negative impact on Colorado potato beetle growth and development than did α-tomatine. α-Chaconine at 2.4 mM did not impair Colorado potato beetle performance relative to Colorado potato beetle reared on control diets. α-Chaconine plus α-solanine, at concentrations commonly found inSolanum tuberosum L. foliage (0.6 and 0.3 mM respectively), did not impair Colorado potato beetle performance. The steroidal aglycone solanidine (2.4 mM) had a significant negative impact on Colorado potato beetle performance. Results are discussed in the context of host-plant resistance and insect-plant interactions.