Van Waddill

CONTACT TOXICITY OF FOUR SYNTHETIC PYRETHROIDS AND METHOMYL TO SOME ADULT INSECT PARASITES

Four synthetic pyrethroids: fenvalerate, permethrin, buthrenin, and NRDC 149 ((@+) -d-cyano-m-phenoxybenzyl (@+)-cis, trans -3-(2,2-dichlorovinyl)-2-dimethyl-cyclo-propanecarboxylate) as well as the carbamate methomyl were evaluated at 2 rates for contact toxicity to adults of 5 parasite species, (Diglyphus intermedius (Girsault) (Eulophidae), Opius bruneipes (Gahan) (Braconidae), Apanteles sp., Copidosoma truncatellum (Dalman) (Encrytidae), and Telenomus remus (Nixon) (Scelionidae)). Methomyl was highly toxic to all species at the maximum rate tested while at least 1 synthetic pyrethroid caused significantly less mortality per species than methomyl. Fenvalerate was generally the least toxic to the parasites and thus the most promising candidate for use in a pest management program on tomatoes for control of the tomato pinworm, Keiferia lycopersicella (Walsingham) and the vegetable leafminer, Liriomyza sativae (Blanchard).

Effect of host age, parasitoid age and temperature on interspecific competition between Chelonus insularis Cresson, Cotesia marginiventris Cresson and Microplitis manilae Ashmead

The effects of host age, age of Cotesia marginiventris Cresson adults and temperature on interspecific competition between fall army worm (FAW), Spodoptera frugiperda (J. E. Smith), larval parasitoids C. marginiventris, Microplitis manilae Ashm. and the egg-larval parasitoid, Chelonus insularis Cresson were studied. All parasitization results for C. marginiventris and M. manilae were from FAW larvae parasitized as eggs by C. insularis. The maximum reproductive potential for C. marginiventris was achieved in hosts initially parasitized by C. insularis and were 36 to 48 hours old and at a temperature of 25°C. No host discrimination was found for C. marginiventris between larvae containing a developing C. insularis and non-parasitized larvae. The optimum parasitoid age for C. marginiventris during the host exposure period was 48 to 96 hr. Younger or older parasitoids were not able to compete as successfully against C. insularis. A sex ratio of approximately 65% males was present in C. marginiventris progeny produced from parents ranging in age from 24 to 108 hr old. Egg to adult development times at 25°C were 17 and 26 days for C. marginiventris and C. insularis, respectively. In multiple parasitized larvae, C. marginiventris appeared to physically attack and destroy the larvae of C. insularis. However, M. manilae larvae died after 6 days without appearing to have been physically attacked in hosts containing C. insularis.RésuméLes effets de l’âge de l’hôte, de l’âge des adultes de Cotesia marginiventris Cresson et de la température sur la compétition interspécifique entre les parasitoïdes des larves, C. marginiventris, Microplitis manilae Ashm. et celui des oeufs et des larves, Chelonus insularis Cresson, sur la chenille légionnaire, Spodoptera frugiperda ont été étudiés. Les résultats montrent que le parasitisme au niveau des larves est dû à C. marginiventris tandis que les oeufs sont parasités par C. insularis. Le potentiel maximun de reproduction de C. marginiventris est atteint sur des hôtes initialement parasités par C. insularis âgés entre 36 et 48 heures à la température de 25°C. Aucune discrimination de l’hôte n’est observée par C. marginiventris que les larves soient parasitées ou non par C. insularis. L’âge optimum de C. marginiventris pendant la période d’exposition de l’hôte est de 48 à 96 hr.; des individus jeunes ou plus âgés ne sont pas capables de compétir avec succès contre C. insularis. Un sex ratio de 65% environ de mâles est observé dans la descendance de C. marginiventris issue de parents âgés entre 24 et 108 hr. La durée de développement de l’oeuf à l’adulte à 25°C était respectivement de 17 et 26 jours pour C. marginiventris et C. insularis. Au niveau des larves multiparasitées, C. marginiventris attaque et détruit les larves de C.insularis, cependant les larves de M. manilae meurent après 6 jours sans montrer de signes qu’elles ont été attaquées dans des hôtes renfermant C. insularis.

Parasitization of Fall Armyworm Larvae on Volunteer Corn, Bermudagrass, and Paragrass

Fall armyworm larvae, Spodoptera frugiperda (J. E. Smith), were collected from volunteer corn at Homestead, FL from April through August and from Bermudagrass, Cynondon dactylon (L.), and paragrass, Brachiarie mutica (L.), in August and September at Belle Glade, FL. Chelonus insularis Cresson, Temelucha sp., and Apanteles marginiventris (Cresson) parasitized 44, 11, and 5% of all larvae collected, respectively. The principal parasite in volunteer corn was C. insularis and A. marginiventris was primarily found in Bermudagrass. Larvae collected from corn were the most frequently attacked with 78 and 72% of the 3rd and 4th instars parasitized, respectively. Larval abundance and parasitization rates in corn were greatest during the months of June and July.

BIOLOGY AND HOST ACCEPTANCE OF MICROPLITIS MANILAE (HYMENOPTERA:BRACONIDAE) RAISED ON FALL ARMYWORM LARVAE SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE)

Studies were carried out on host age preference, developmental period and longevity of Microplitis manilae (Ashmead) a larval parasitoid of Spodoptera species imported from Thailand. Experiments conducted with 4 larval age groups (1, 24-48 h; 2, 49-72 h; 3, 73-96 h; 4, 97-130 h) of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), revealed that age groups 1 and 2 were most suitable for the development of the endoparasitoid Microplitis manilae. The highest parasitization rates and the highest proportion of female parasitoids were from larvae in the 2nd age group. The developmental period of M. manilae ranged between 13-18 days for temperatures between 23-27 @*C, 50-70% RH and 14:10 LD photoperiod. Highest parasitization was observed for M. manilae when 2 females were exposed to 20 hosts for 30 min at 26 @+ 1 @*C. Adult longevity of males and females was approximately 6 days at 26 @+1 @*C. This biological information will be used for rearing this parasitoid for additional laboratory studies or in the event M. manilae is considered for inundative or inoculative releases.

Pests of cassava in south Florida.

Insect pests found on cassava, Manihot esculenta, in southern Florida included the cassava hornworm, Erinnyis ello L., cassava shoot fly, Neosilba perezi Romero and Ruppel, banded cucumber beetle, Diabrotica balteata Le Conte, southern armyworm, Spodoptera eridania Cramer, cassava scale, Aonidomytilus albus Cockerell, Caribbean black scale, Saissetia neglecta de Lotto, Mexican mealybug, Phenacoccus gossypii Townsend & Crockerell, Phenacoccus sp. near obscurus and several species of stem borers. The mites, Mononychellus caribbeanae McGregor, Tetranychus urticae Koch and Panonychus citri (McGregor) were found feeding on the leaves. The lace bug, Corythuca gossypii Fabricius, is recorded for the first time as a cassava pest.

Biology of a Predaceous Stinkbug, Stiretrus Anchorago, (Hemiptera: Pentatomidae)

Stiretrus anchorago (F.) was collected from S. C. soybean fields and reared at 3 constant temperatures. Larvae of Epilachna varivestis Mulsant were used as prey for S. anchorago in life history studies. Female adults lived an average of 46.0 29.6, and 12.6 days; males 38.2, 24.8, and 22.4 days at constant temperatures of 18.3, 26.7, and 32.2@*C, respectively. Mean numbers of eggs per female were 12.6, 57.3, and 15.0 at 18.3, 26.7, and 32.2@*C, respectively. The immature stages (eggs and instars) completed development in 42.8, 24.6, and 22.6 days at 18.3, 26.7, and 32.2@*C, respectively. Eggs laid by field collected females and held at 26.7@*C were more viable (88.5%) than eggs from laboratory reared females (19.0%). Only infertile eggs were produced by females fed Galleria mellonella (L.) larvae exclusively.