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In a study of hitchhiking or contaminating insect pests on international cargo aircraft at Miami International Airport from 1998 to 1999, it was found that contamination rates were greatest, 23%, on cargo flights from Central America and much lower, near 5%, on flights from all other regions. We reanalyzed the study data to test for associations between contaminated flights and factors such as season, cargo type, and time of departure (night or day), and developed probabilistic models for predicting insect pest arrivals by region and pest risk levels. Significant (P < 0.05) associations were detected between contaminated flights and (1) wet season flights from Central America, (2) flights carrying plant products and clothing or fabrics, and (3) flights departing at night from the country of origin. In Monte Carlo simulations, numbers of arriving mated insect pests were greatest for cargo flights from Central America, because of great contamination rates, and South America, because of the large volume of flights from there. Few insects arrived on flights from the Caribbean, and few high-risk insects arrived from anywhere. Although the likelihood of establishment in South Florida via this pathway could not be estimated, based upon arrivals the greatest threats were posed by moderate-risk insect pests on flights from Central and South America. Simulations indicated that switching to daytime departures only reduced pest arrivals by one-third. The simplest mechanism for pathway entry that explains the associations found is that insects entered aircraft randomly but sometimes remained because of the presence of certain cargo types. Hence, contamination rates were greater during the wet season because of greater abundance locally, and on nighttime flights because of greater abundance around lighted loading operations. Empty planes probably had no pests because pests had no access to holds. Thus, the best mitigation strategies for this pathway will likely be those that exclude insects from holds or reduce the attractiveness of night loading operations. Optimizing inspections based on associations is also possible but will be less effective for regions such as South America, with high flight volumes and low contamination rates. Comparisons to other pathways indicates the potential importance of hitchhikers on cargo aircraft at MIA.

Post‐fundatrix lineages of Aphis rubicola Oestlund exposed to continual short‐day photoregimes of 8 or 10 h resisted sexual‐promoting influences for varying lengths of time. Lineages originating from fundatrices and continually exposed to short days lasted 18.5–31.5 days before consisting of 50% ovipara producers. When 13–67 16‐h days preceded continual short‐day exposure, lineages lasted 11.5–19 days before consisting of 50% ovipara producers. A short‐lived interval timer for the production of oviparae was thus demonstrated. The timer expired gradually, not abruptly, so that the greater the distance was in days from the newly hatched fundatrix, the less was the time required for 50% of the adults to be ovipara producers (r = −0.892). Weakening in a curvilinear fashion, the timer lost its greatest amount of resistance between the 5th and 13th days of deposition by fundatrices. ZUSAMMENFASSUNG EIN “INTERVALL‐ZEITMESSER” FÜR DIE BILDUNG VON OVIPAREN BEI APHIS RUBICOLA (HOMOPTERA: APHIDIDAE) Linien von Fundatrigenien von Aphis rubicola Oestlund, welche kontinuierlichem Kurztag von 8 rsp. 10 Stunden ausgesetzt wurden, widerstanden den die Bildung von Geschlechtstieren fördernden Einflüssen für verschiedenlange Zeit. Linien, welche ständig Kurztag ausgesetzt wurden, brauchten 18,5 bis 31,5 Tage, bis sie zu 50% aus Sexuparen bestanden. Wenn die Linien vorgängig für 26,5 bis 80,5 Tage Langtag (16 Stunden) ausgesetzt wurden, bevor sie zu Kurztag kamen, brauchte es 11,5 bis 19 Tage, bis 50% Sexupare waren. Damit wurde ein kurzlebiger Intervall‐Zeitmesser für die Bildung von Geschlechtstieren nachgewiesen. Dieser Zeitmesser erlöscht allmählich in krummliniger Form und nicht plötzlich. Je grösser der zeitliche Abstand von der Junglarve der Fundatrix, um so kleiner war die erforderliche Zeit, bis 50% der Adulten Sexupare waren (n = −0,892).

Higher temperatures led to a less rapid transition from virginopara production to ovipara and male production by apterous, virginoparous Aphis rubicola Oestlund exposed from birth to short‐day conditions. At 19.4° more than 95% of the progeny were sexuals, whereas only ca. 58% were such at 25.1°. A 2‐day cessation of reproduction preceded male production at 19.4° but not at 21.5° and 25.1°. Temperature increases led to the earlier deposition of most progeny, an earlier, more extended period of male production, a smaller decrease in reproductive rate prior to male production, and a lower ovipara: male ratio. RÉSUMÉ L'INFLUENCE DE LA TEMPERATURE SUR LA PRODUCTION DE SEXUES PAR APHIS RUBICOLA EN JOURS COURTS Des températures plus élevées ont provoqué un passage moins rapide de la production de virginipares à la production d'ovipares et de mâles, par des virginipares d'Aphis rubicola Oestlund, exposées depuis la naissance à des jours courts. A 19,4° les sexués constituaient plus de 95% de la descendance, contre seulement 58% à 25,1°. La reproduction s'arrête pendant deux jours avant la production de mâles à 19,4° mais non à 21,5° ni 25,1°. L'élévation de la température a provoqué l'émission plus précoce de la plupart des descendants; une production de mâles plus précoce et plus prolongée précédée d'une moindre diminution de la production, et enfin un rapport ovipare‐mâle plus faible.

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