The total world area covered by greenhouses is very small (approximately 150,000 ha; Table 1), yet developments in biological pest control in this cropping system have been significant and are of particular interest for several reasons. Few specialists in biological control anticipated that it would be possible to employ natural enemies in greenhouses because growing vegeta­ bles and ornamentals in this protected situation is expensive and pest damage is not tolerated. Successful greenhouse growers cannot afford to risk any damage from insects for idealistic reasons, e .g. a belief that biological control may cause fewer negative side effects than chemical control. If chemical control is more effective, growers will certainly use it. In tomatoes, for example, pest control represents only 1-2% of the total overall cost of production (52); thus, the cost of pest control is not a limiting factor. Yet although chemical control is easy and inexpensive, the development and application of biological control has been remarkably fast. Biological control in greenhouses is also worthy of attention because (a) a new system of introducing natural enemies is used; (b) research on pests in greenhouses has resulted in extensive theoretical developments in understanding how biologi­ cal control works; and (c) a close relationship among researchers, develop­ ment and extension workers, and growers has resulted in a rapid transfer and use of information on biological control in greenhouses. To date, most of the

Biological and Integrated Pest control in Greenhouses

1. Chrysoperla carnea is an important predatory insect in maize. To assess the ecological effects of Bt-maize, expressing the Cry1Ab protein, on larvae of this predator, the following factors were examined: (1) the performance of three prey herbivores (Rhopalosiphum padi, Tetranychus urticae, and Spodoptera littoralis) on transgenic Bt and non-transgenic maize plants; (2) the intake of the Cry1Ab toxin by the three herbivores; and (3) the effects on C. carnea when fed each of the prey species.



2. The intrinsic rate of natural increase (rm) was used as a measure of performance for R. padi and T. urticae. No difference in this parameter was observed between herbivores reared on Bt or non-transgenic plants. In contrast, a higher mortality rate and a delay in development were observed in S. littoralis larvae when fed Bt-maize compared with those fed the control maize plants.



3. The ingestion of Cry1Ab toxin by the different herbivores was measured using an immunological assay (ELISA). Highest amounts of Cry1Ab toxin were detected in T. urticae, followed by S. littoralis, and only trace amounts detected in R. padi.



4. Feeding C. carnea with T. urticae, which were shown to contain the Cry1Ab toxin, or with R. padi, which do not ingest the toxin, did not affect survival, development, or weight of C. carnea. In contrast, a significant increase in mortality and a delay in development were observed when predators were fed S. littoralis larvae reared on Bt-maize.



5. A combined interaction of poor prey quality and Cry1Ab toxin may account for the negative effects observed on C. carnea when fed S. littoralis. The relevance of these findings to the ecological risks of Bt-maize on C. carnea is discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2311.2002.00436.x

Uptake of Bt-toxin by herbivores feeding on transgenic maize and consequences for the predator Chrysoperla carnea

I examined case studies of density-related parasitism in insect host-para- sitoid systems reported in the literature. For 171 examples, the frequency of density de- pendence was 25% (n = 43), of inverse density dependence 23% (n = 39), and of inde- pendence 52% (n = 89). This is a considerably lower frequency of density dependence than previously reported in other reviews (Lawton and McNeill 1979, Lessells 1985, but see Dempster 1983). Biological features of case histories gave few clues as to the expected frequency of density dependence. Such features included host order, life stage attacked, parasite group, native vs. introduced status of hosts or parasites, number of attacking parasitoid species, mobile vs. sedentary hosts, and monophagous vs. polyphagous hosts or parasitoids. Biotic and abiotic factors may, however, provide good reasons for a low overall frequency of density dependence.

The Frequency of Density Dependence in Insect Host-Parasitoid Systems

https://pure.uva.nl/ws/files/4271053/61865_VanRijn08_1.pdf

Honeydew as a food source for natural enemies: Making the best of a bad meal?

Biological control of arthropod pests using banker plant systems: Past progress and future directions

Aphid parasitoids (Hymenoptera, Aphidiidae): biology, host selection and use in biological control.

Rate of development and longevity were studied inAphidius erviHaliday andAphidius platensisBrethes, two parasites of the green peach aphid,Myzus persicaeSulz. On paprika,A. ervi developed from egg to adult in 27.3 days (at 15°C) and 19.9 days (21°C),A. platensis in 19.9 days (15°C), 15.6 days (21°C) and 12.4 days (24°C). The period from oviposition to mummification was in both species roughly twice as long as the period from mummification to adult emergence. Males emerged slightly before females.

Duration of development and longevity inAphidius ervi andAphidius platensis [Hym.: Aphidiidae], two parasites ofMyzus persicae [Hom.: Aphididae]

The parasitoidEphedrus cerasicola Starý oviposited in all 4 nymphal instars and in newly moulted adults ofMyzus persicae (Sulzer). The different host categories were offered with no choice. The duration of an oviposition increased with the age of nymphs, being about 13, 18, 21, 22, and 17 s from 1 st instars to adults, respectively. Observations of number of stabbing attacks prior to oviposition, percent of the encounters not resulting in oviposition, time from first encounter to oviposition, handling time and aphid defensive behaviour also indicated that 1 st instarM. persicae are most easily parasitized. The behaviour ofE. cerasicola in encounters with unparasitized and parasitized hosts, suggested that the parasitoid could discriminate. In encounters with parasitized 1 st to 4th instar aphids,E. cerasicola used only the antennae in 80% of the encounters that resulted in discrimination.

Oviposition behaviour of Ephedrus cerasicola (Hym. Aphidiidae) parasitizing different instars of its aphid host

In the present study the predation rate of Chrysoperla carnea (Stephens) on eggs and larvae of the lepidopterous species Mamestra brassicae (L.) was investigated including the prey's influence on survival and development. The experiments were done at 20 ± 1°C and L:D = 16:8. C. carnea larvae were fed on eggs and first instar larvae of M. brassicae, respectively. In both cases the daily predation rate of C. carnea increased slowly during the two first instars and reached a peak in the third larval instar. During the third instar 87% and 85% of the total numbers of M. brassicae eggs and larvae, respectively, were consumed. C. carnea preyed on a mean total of 312 M. brassicae eggs and 232 M. brassicae larvae during its larval development. The mean daily predation rate of C. carnea reached a maximum of 106.6 eggs of M. brassicae and 46.1 larvae of M. brassicae. C. carnea consumed a total of 32 mg of M. brassicae eggs and 70 mg of M. brassicae larvae during its larval development. The developmental time of C. carnea fed on M. brassicae eggs and larvae was 27.4 and 21.5 days, respectively. Almost 10% of C. carnea died when reared on M. brassicae eggs and 15% died when reared on M. brassicae larvae. The quality aspect of the prey is discussed.

The predation of Chrysoperla carnea (Neurop., Chrysopidae) on eggs and larvae of Mamestra brassicae (Lep., Noctuidae)

The functional responses of the parasitoidEphedrus cerasicola Starý parasitizingMyzus persicae (Sulzer) on a paprika plant, were studied for single females at different host densities (1 to 120 aphids per 1.8 dm3) during 3 different time periods (1 hr, 6 hrs, 24 hrs) at 21 °C.

T. Hofsvang

Papers

Aphid parasitoids (Hymenoptera, Aphidiidae): biology, host selection and use in biological control.

Duration of development and longevity inAphidius ervi andAphidius platensis [Hym.: Aphidiidae], two parasites ofMyzus persicae [Hom.: Aphididae]

Oviposition behaviour of Ephedrus cerasicola (Hym. Aphidiidae) parasitizing different instars of its aphid host

The predation of Chrysoperla carnea (Neurop., Chrysopidae) on eggs and larvae of Mamestra brassicae (Lep., Noctuidae)

Functional responses to prey density of Ephedrus cerasicola [Hym.: Aphidiidae] , an aphidiid parasitoid of Myzus persicae [Hom.: Aphididae]