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A 17-day trip was made through the States of Sao Paulo, Mato Grosso, Rondania Territory, Goias, and Minas Gerais, Brazil, to study the Solenopsis saevissima (Smith) complex. Special emphasis was on the distribution and ecology of Solenopsis invicta Buren. S. invicta was established in an area bordered by Caceres, Rondonopolis, Chapada, and Terenos in the State of Mato Grosso, and was also found at Porto Velho, Rondonia Territory. Active colonies were present only in moist or protected areas. This study reconfirmed a previous postulation that areas of Mato Grosso were a part of the homeland of S. invicta , the “red imported fire ant” of southeastern United States.

Developmental data on the velvetbean caterpillar (VRC), collected in both controlled-environment and field settings, allowed the computation of parameters depicting the temperature-dependent development of VBC. These parameters were associated with a previously derived poikilothermic developmental model and were derived to allow computation of the distribution of stage-specific emergence times for the VBC, given any particular temperature regime. These evaluations elucidate several problems (e.g., mortality) associated with attempts to validate single processes (e.g., development) in complex field environments.

Effects of temperature on velvetbean caterpillar (VBC), Anticarsia gemmatalis HA¼bner (Lepidoptera: Noctuidae), oviposition, egg hatch, and adult longevity were investigated at 3 regimes: (1) constant temperatures of 21.1°, 23.9°, 26.7°, 29.4°, and 32.2°C (on artificial diet); (2) variable temperatures simulating “summer” at Gainesville, FL (artificial diet and soybean foliage); (3) field-reared adults (in cages on soybean). Mean oviposition was highest at 26.7°C (842.2 egg/female) and lowest at 32.2° (310.0 eggs/female) constant. Peak average daily oviposition was higher for young females and was delayed as temperatures decreased. Mean egg hatch was high initially but decreased with maternal age. Female longevity varied from a mean of 24.8 days (21.1°C) to 11.2 days (32.2°C). Unmated females lived significantly (I± = .05) longer than mated females at a given temperature.

Effects of soybean, Glycine max (L.) cv. Bragg, phenology on leaf consumption and development of the velvetbean caterpillar (VBC), Anticarsia gemmatalis Hubner, were investigated at 26.7 ± 1° C, 14L:10D photoperiod, and RH > 80%. Soybean plant stages were designated as early vegetative (V2–V5), late vegetative (V5–V8), flowering (R1–R2), pod set to pod fill (R4–R6), and senescent (R7–R8). Mean leaf fresh weight consumed by 4th- and 5th-instar VBC larvae declined as plant phenology progressed. Dry-weight consumption did not tend to decline with plant phenology and was more uniform for all plant growth stages than the freshweight values. Mean larval development time varied from 12.6 to 14.3 days, and mean time from egg hatch to adult varied from 21.9 to 23.4 days when larvae were fed late-vegatative and senescent foliage, respectively. Larvae fed senescent leaves produced pupae with reduced weight. Sex ratio (male/female) varied from 0.83 (flowering stage) to 1.37 (late-vegetative stage).

Different concentrations of nuclear polyhedrosis virus (NPV) and insecticides (carbaryl and methomyl) were applied to natural infestations of the velvetbean caterpillar (VBC), Anticarsia gemmatalis Hubner, on soybean. Their efficacy in reducing VBC larval populations and their effect on naturally occurring epizootics of the entomogenous fungus Nomuraea rileyi (Farlow) Samson were determined. Persistence of the virus in the field was measured. Virus application rates of 75, 145, and 287.5 larval equivalents (LE)/ha suppressed VBC populations below damaging levels. Most virus-induced mortality occurred at 6, 7, and 8 days after spraying. The virus retained 65 to 70% of its original pathogenicity 7 days after treatment and 25 to 35% at 10 days. All virus doses greatly reduced the magnitude of a N. rileyi epizootic. Carbaryl or methomyl applied once at 0.28 or 0.07 kg AI/ha effectively suppressed VBC populations below economic levels for the remainder of the season. High concentrations of insecticides reduced the impact of N. rileyi by reducing the natural substrate, VBC larvae.

Significant differences in infection rates of the entomogenous fungus, Nomuraea rileyi (Farlow) Samson among populations of Anticarsia gemmatalis (Hubner) in soybean treated with benomyl, benomyl and methyl parathion, and benomyl and carbaryl were observed. Development of N. rileyi was delayed in treated plots for at least 3 weeks. The yield of the check plot was significantly higher than that of the pesticide treated plots.

The inter-instar susceptibility of the velvetbean caterpillar to a nucleopolyhedrosis virus was quantitated. Analysis of response curves revealed a 930-fold range in susceptibility between the most sensitive and the most resistent individuals in these larval populations. The LD50 values for 2nd, 3rd, 4th, and 5th instars were 103, 432, 682, and 4100 polyhedra/larva, respectively. At 26.7°C the virus replicated efficiently in all larval instars. Virus replication was slower at lower temperatures (15.6°C, 21.1°C) but the cumulative virus mortality at these these temperatures were similar fo that achieved at 26.7°C. Incubation at higher temperatures (32.2°C), however, caused a 30–50% less virus mortality than occurred at lower temperatures.

A microsporidan, Thelohania sp., was isolated from workers of the black imported fire ant, Solenopsis richteri Forel, in Montevideo, Uruguay, and Las Flores, Argentina, and from a Solenopsis sp. in Montevideo, in March and May of 1974. Many of the colonies exhibiting high levels of infection in March were abandoned or drastically reduced in size when re-examined in May. No disease was observed in populations of S. blumi Buren or S. quinquecuspis Forel.

A method was developed for determining the number of cadavers of the velvetbean caterpillar, Anticarsia gemmatalis (Hubner), infected with the fungal pathogen Nomuraea rileyi (Farlow) Samson in the developmental stage just prior to conidia formation (white stage) in a soybean field. One-third of the total number of cadavers in this developmental stage were observed to fall on the shake cloth during population sampling; (approximately two-thirds remained on the plant). Estimates of white cadaver counts from laboratory-held lots of field-collected larvae did not correlate with actual field counts.

Reinfectivity studies were conducted on late instar lovebug larvae, Plecia nearctica Hardy (Diptera-Bibionidae), inoculated with Tolypocladium cylindrosporum Gams, Metarhizium anisopliae (Metch.) Sor. and Beauveria bassiana (Bals.) Vuill. which were isolated and identified from dead larvae. Two tests demonstrated that each fungus apparently affected larval mortality; however, data analyses indicated that only B. bassiana caused significant mortality levels (27% to 33%). Problems related to reinfectivity tests are discussed. Nine additional fungi are reported from dead and moribund larvae collected in the field.

Populations of Plecia nearctica Hardy were surveyed during the spring and fall of 1973 to monitor adult flights which usually occur in May and September. The May adult flight was noticeably smaller. A large flight was observed in September. During early spring, 5 species of fungi were isolated and identified from dead and moribund lovebug larvae collected in the Gainesville area. In the fall, 2 additional fungal species were isolated, 1 from adults during the September flight and 1 from laboratory reared larvae.

An epizootic caused by the entomogenous fungus Spicaria rileyi (Farlow) occurred among populations of the velvetbean caterpillar, Anticarsia gemmatalis Hubner on soybeans, Glycine soja, Sieb. and Zucc. in August and September 1970. The natural outbreak was monitored in Quincy where environmental conditions favoring development of the fungus prevailed during July through September. The development of the epizootic was related to the build-up of insect populations, and the development and dissemination of the fungus.