Comparative activity of baculoviruses against the codling moth Cydia pomonella and three other tortricid pests of tree fruit.

The granulovirus of Cydia pomonella (L.) (CpGV) offers potential for selective control of codling moth. Two major limitations of CpGV are its narrow host range and lack of persistence in the orchard agroecosystem. The nucleopolyhedroviruses of the alfalfa looper Autographa californica (Speyer) (AcMNPV) and those of the celery looper Anagrapha falcifera (Kirby) (AfMNPV) have broad host ranges. Comparative assays of CpGV, AcMNPV, and AfMNPV against codling moth neonate larvae revealed a 54-93-fold greater susceptibility of codling moth to the granulovirus than to the two nucleopolyhedroviruses based on the LC(50) values for each virus. The LC(50)s for CpGV, AfMNPV, and AcMNPV were 32.7 capsules/mm(2), 1.77 x 10(3) occlusion bodies (OBs)/mm(2), and 3.05 x 10(3)OBs/mm(2), respectively. The LT(50) determined for AfMNPV using an approximate LC(95) of the virus against neonate larvae was 3.6 days. Histological examination of tissues in moribund codling moth larvae that had been treated with AfMNPV revealed the presence of nonoccluded and unenveloped virus rods in midgut tissue. Neither OBs nor signs of infection were detected in other tissues. The activity of AfMNPV was also evaluated in three other tortricid apple pests (obliquebanded leafroller, Choristoneura rosaceana (Harris); Pandemis leafroller, Pandemis pyrusana Kearfott; and the oriental fruit moth, Grapholitha molesta (Busck)). Codling and Oriental fruit moths were significantly more susceptible to AfMNPV than were the two leafroller species.

Integration of nonchemical treatments for control of postharvest pyralid moths (Lepidoptera: Pyralidae) in almonds and raisins.

We propose a treatment strategy combining an initial disinfestation treatment with one of three protective treatments as an alternative for chemical fumigation of almonds and raisins for control of postharvest insect populations. Initial disinfestation treatments using low oxygen controlled atmosphere (0.4% O2) were designed to disinfest product of field populations of pyralid moths; navel orangeworm, Amyelois transitella (Walker), in almonds and raisin moth, Cadra figulilella (Gregson), in raisins. The protective treatments were cold storage (10 degrees C), controlled atmosphere (5% O2) storage, and application of the Indianmeal moth granulosis virus, and were designed to prevent establishment of Indianmeal moth, Plodia interpunctella (Hübner). The initial disinfestation treatment was effective against laboratory populations of navel orangeworm and raisin moth. Efficacy of protective treatments was determined by exposure of commodities to laboratory Indianmeal moth populations at levels far higher than those found in commercial storage facilities. All three protective treatments prevented development of damaging Indianmeal moth populations as measured by pheromone trap catches and evaluation of product samples. Quality analysis by commercial laboratories showed that overall product quality for all protective treatments was maintained at levels acceptable by industry standards.

Dose-morality and large-scale studies for controlling codling moth (Lepidoptera: Tortricidae) eggs on 'd'Agen' plums by using methyl bromide.

Codling moth, Cydia pomonella (L.), eggs on 'd'Agen' cultivar of plums, Prunus salicina Lindl., were treated with methyl bromide to determine if a quarantine treatment could be developed so that the plums could be exported to Japan from the United States. Small-scale tests consisted of treating codling moth eggs on plums with various doses of methyl bromide at 20 degrees C for 2 h. Small-scale tests showed that 0- to 24-h-old eggs of codling moth on the plums were controlled by doses > 22.5 g/m3. Because testing showed that 48 g/m3 had no adverse effect on the quality of plums, this dose was chosen for large-scale testing to establish the quarantine dose. Large-scale tests consisted of treating plums at 18.5 degrees C for 2 h using methyl bromide at a dose of 48 mg/liter. Large-scale tests showed that the dose of 48 g/m3 killed all 0- to 24-h-old codling moth eggs exposed on plums in packing cartons without affecting the quality of the plums.

Interaction of nuclear polyhedrosis virus with catechols: Potential incompatibility for host-plant resistance against noctuid larvae.

Two major orthodihydroxy phenolics ofLycopersicon esculentum, rutin and chlorogenic acid, have previously been identified as potential sources of host-plant resistance against the tomato fruitwormHeliothis zea. We report here the possible incompatibility of these chemically based resistance factors with viral control ofH, zea. We have found that both rutin and chlorogenic acid significantly inhibited the infectivity of nuclear polyhedrosis viruses. Chlorogenic acid, when added to tissue culture medium containing TN-368 ovarian cells, inhibited the infectivity of a multiply embedded virus (AcMNPV) by over 86%. Rutin or chlorogenic acid, when fed toH. zea, inhibited the infectivity of a singly embedded nuclear polyhedrosis virus (HzSNPV), with the greatest degree of inhibition occurring at low doses of viral inoculum. Additionally, the ingestion of these phytochemicals significantly prolonged the survival time of virally infectedH. zea larvae. These results suggest that the effectiveness of nuclear polyhedrosis viruses in controllingH. zea populations may be adversely affected by varieties ofL. esculentum with significant levels (eg. 3.5 µmol/g wet weight) of rutin or chlorogenic acid.

Susceptibility of the Colorado Potato Beetle and the Sugarbeet Wireworm to Steinernema feltiae and S. glaseri.

In laboratory tests, larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), and the sugarbeet wireworm (SBW), Limonius californicus (Mannerheim), were exposed to the nematodes Steinernema feltiae Filipjev (Mexican strain) (= Neoaplectana carpocapsae) and S. glaseri Steiner in soil. S. feltiae caused significantly higher mortality in SBW larvae than did S. glaseri, but both nematode species were equally effective against CPB larvae. The minimum concentration of S. feltiae for 100% mortality of CPB larvae after 13 days was 157 nematodes/cm(2) of soil, and the LC based on 6-day mortality was 47.5 nematodes/cm(2); in contrast, 100% mortality of SBW larvae was not achieved with even the highest concentration tested, 393 nematodes/cm(2). CPB adults emerging from nematode-contaminated soil were not infected. In field cage tests, S. feltiae applied to the soil surface at the rates of 155 and 310 nematodes/cm(2) soil caused 59% and 71% mortality, respectively, of late-fourth-instar spring-generation CPB, and 28% and 29% mortality, respectively, of SBW. No infection was obtained when larvae of summer generation CPB and SBW were placed in the same cages approximately 6 weeks after nematodes were applied to the soil. Inundative soil applications of S. feltiae, though cost prohibitive at present, were effective in reducing caged CPB and SBW field populations.