Since potato leafroll virus multiplies in the green peach aphid, Myzus persicae, the effect of the virus on the biology of its vector was investigated. Observations were made regarding the longevity and the reproduction rate of viruliferous and non-viruliferous aphids on leafroll-diseased and healthy plants of Physalis floridana. The same matters were investigated for both viruliferous and non-viruliferous aphids on seedlings of Chinese cabbage (Brassica pekinensis). It was shown that on leafroll-diseased plants of P. floridana the aphids produced more progeny than on l~ealthy ones, although the average number of progeny produced per day in both cases was almost the same. On healthy Chinese cabbage seedlings there was no difference in average length of the larval and adult stages, number of progeny per aphid, and number of progeny per day, between viruliferous and non-viruliferous aphids. Evidence was obtained that the virus does not influence the development of its vector. Measurements of oxygen consumption of both viruliferous and non-viruliferous aphids point in the same direction.

Insect‐to‐insect transmission of potato leaf roll virus proved possible by injecting either juice or haemolymph from viruliferous Myzus persicae into virus‐free ones. In serial transmission experiments, in which injection of haemolymph was practised, the virus could be carried through as many as 15 successive aphid‐to‐aphid passages without access of inoculated insects to any plants that are susceptible to leaf roll. The theoretical dilution of original virus used for the inoculation in the 15th passage would have been approximately 10−21. It is concluded that such persistence of virus in the aphids could only be explained on the assumption that the insect itself sustains reproduction of the virus. Zusammenfassung 1. Das Blattrollvirus der Kartoffel konnte durch Injektion von Preßsaft oder Blut virusinfizierter Myzus persicae (Sulz.) auf virusfreie Insekten übertragen werden. 2. Bei Serien‐Übertragungen unter Verwendung von Blutinjektionen blieb das Virus in 15 aufeinander folgenden Generationen ursprünglich virusfreier Blattläuse erhalten. Hierbei wurde nach der Injektion als Zwischenwirt der blattrollunempfindliche chinesische Kohl benutzt. 3. Die theoretische Verdünnung der ursprünglichen Virusmenge pro Blattlaus betrug nach der 15. Passage ungefähr 10−21. Injektion des auf 1: 104 verdünnten Blutes virusinfizierter Läuse ergab dagegen in keinem Fall Infektionsfähigkeit (Tabelle III und IV). 4. Die Existenz einer Latenz‐Periode bei der Übertragung konnte nach Injektion kleiner Virusmengen bewiesen werden. Verdünnung des injizierten Blutes verlängerte diese Periode (Tabelle I und II). 5. Diese Befunde deuten auf Vermehrung des Virus innerhalb der Blattläsen. 6. Wenn virusinfizierte Blattläuse auf chinesischem Kohl gehalten werden, zeigt ihre Infektionsfähigkeit deutlich periodische Schwankungen (Fig. 1).

No abstract

The ability of the green peach aphid, Myzuspersicae, to transmit potato leafroll virus after a six-hours' acquisition feeding period on leaf roll-diseased plants of Physalis floridana, followed by a feeding for different lengths of time on Chinese cabbage (Brassica pekinensis) was determined. Virus transmission was optimally efficient at about the ninth day after aphid birth. If after a one-hour acquisition feeding period on a virus source the aphids were starved for different numbers of days at 4~ the efficiency increased with increasing starvation periods. Starvation at 4 ~ prior to the one-hour acquisition feeding period had no effect on the ability to transmit the virus. Starvation of larvae at 4 ~ did not prevent them completing their larval stage in about 9-10 days when transferred to plants at 20 ~

The digestive system of Anoecia has a short foregut which opens into a dilated sto mach via a valve. The stomach is made up of triangular cells with a merocrine se cretion. The transition from the stomach to the intestine is marked by a sharp loop. The first and second regions of the intestine form a compact structure. The second region contains groups of three small cells (triplets) among the strongly vacuolated intestinal cells. The descending intestine opens into the rectum, which terminates at the anal opening. These findings are in accordance with the conception of Heie (1980) that Anoecia must be placed outside the family Thelaxidae.