Tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), females can copulate multiple times creating the possibility for sperm competition. We used a colony lacking wild pigmentation on the wings (albino-type) for an experiment in which females double mated. Females copulated 2 days apart with two, 2-day-old males, one albino-type and one wild-type, or in the opposite sequence. A third of the females produced offspring from the first mate, and this group was significantly biased toward producing albino-type compared to wild-type progeny. A fourth of the females produced offspring from the second male exclusively and within this group was a significant bias toward wild-type compared to albino-type progeny. Almost half of the females produced offspring sired in equal proportions by both males simultaneously or in alternated paternities throughout all the reproductive life. These results suggest that regardless of the order in which moths mated, wild-type sperm had potential superior competitiveness. Therefore, sperm precedence is not the main driving force behind the paternity allocation mechanism in this strain of tobacco budworm.

The relationship between susceptibility of the first laboratory generation of field-collected colonies of bollworm, Helicoverpa zea (Boddie), to the Cry1Ac toxin from Bacillus thuringiensis (Berliner) (Bt) and the crop structure in the surrounding landscape was examined from 2002–2006 in Arkansas. At lesser concentrations of Cry1Ac (10 and 30 μg/ml diet) in diet-incorporated bioassays, colonies of bollworm established from an area with two Bt crops, cotton, Gossypium hirsutum L., and corn, Zea mays L., were less susceptible to Cry1Ac than those from an area with only Bt corn. There were no differences in susceptibilities of colonies established at different months in the areas. On a local scale, there was a positive relationship between susceptibilities of bollworm colonies at greater dosages in bioassays (50 and 100 μg of Cry1Ac/ml of diet) and the percentage of Bt corn acreage within a 0.8-km radius of collection sites. Colonies tended to be less susceptible to Cry1Ac as the amount of Bt cotton increased around collection sites, but these relationships were not significant.

The greenbug, Schizaphis graminum (Rondani), can kill seedlings and reduce the yield of older sorghum, Sorghum bicolor (L.) Moench, and small grains. The objective of this study was to determine effects of different amounts of soil water (−33, −50, −100, and −300 kPa) and nitrogen (21, 50, 100, and 150 ppm) on fitness of biotype I greenbugs on sorghum. The pre-reproductive period of a greenbug ranged from 5.6–7.3 days but was not affected significantly by soil moisture or nitrogen. Lack of soil moisture, but not nitrogen, adversely affected greenbug fecundity and longevity. Significantly most nymphs (44.5) were produced per greenbug and greenbugs lived longest (25.9 and 31.2 days) on sorghum in soil with adequate field-capacity moisture (−33 kPa).

Plants were tallest and produced twice as much dry weight in soil with −33 kPa (67.6 cm tall and 3.7 g per plant) compared with −300 kPa of water potential (56.6 cm and 1.9 g, respectively). The amount of nitrogen in plants in soil with the greatest (−33 kPa) and least (−300 kPa) water potentials was 0.93–0.94%, and was least (0.81%) at the intermediate −100 kPa of water. Plants were tallest (65.8 cm) and produced most dry weight (3.5 g per plant) in soil with 150 ppm of nitrogen, and were shortest (55.2 cm) and produced least dry weight (2.1 g) in soil with only 21 ppm of nitrogen. Plants in soil with the greatest and least amounts of nitrogen had 0.96 and 0.81% nitrogen, respectively. The percentage of nitrogen was greatest (1.08%) in plants in soil with a combination of least moisture (−300 kPa) and most nitrogen (150 ppm).

The population dynamics of the agave scale, Acutaspis agavis (Townsend and Cockerell), on Agave tequilana Weber var. azul were studied in the state of Guanajuato, Mexico. Weekly samples were taken of plants to monitor for the presence of scales and to quantify the different developmental stages of the diaspid, together with its parasitoids and predators. Results showed some reproductive activity throughout the year, with two peaks in the abundance of eggs and first-instar nymphs in May and September, suggesting two generations annually of scales occur in the study area. First-instar nymphs within scales and “crawlers” increased in abundance from April through May and from August through early October, with these differences generally being significantly greater than during winter and mid-summer months. The predatory coccinellid Chilocorus cacti fed on the scale and increased in abundance from August to December when eggs and young scales were most abundant. Parasitism by Aphytis spp. occurred throughout the year. Data presented here indicate that the stages of the agave scale most susceptible to chemical control (first instars, or crawlers) were significantly more abundant in May (first generation) and September (second generation). This indicates that the development of an integrated pest management program to control A. agavis in tequila agave plantations in the region should focus control tactics on these periods of the year.

A mathematical population model (exponential bivariate) was generated and validated to estimate the mean longevity (λ) and hatching period (δ) of nymphal instars of Phoetaliotes nebrascensis (Thomas), Melanoplus lakinus (Scudder), and Boopedon nubilum (Say). P. nebrascensis with 356 insects was most abundant, followed by 280 of M. lakinus, and 220 of B. nubilum; five nymphal instars were found for each species. The model fitted (F_{59, 59, 0.05} = 1.5399) to P. nebrascensis (s_v² / s_m² = 1.2), and M. lakinus (s_v² / s_m² = 0.9), but not to B. nubilum (s_v² / s_m² = 34.2), because this specie was less frequent. The λ values for these species were 7.05, 12.2, and 5.17 days, while δ had values of 33, 35, and 10 days; hatching periods were from 5 July to 7 August, 24 June to 29 July and 20–30 July. M. lakinus hatched before that B. nubilum and P. nebrascensis, and also had a longer hatching period than the other two species, so it was present during a longer period of time in pastures of Durango, Mexico.