P. N. Krishna Moorthy

African marigold as a trap crop for the management of the fruit borer Helicoverpa armigera on tomato

Abstract The possibility of using okra, field bean, pigeon pea, sunflower, maize and marigold as trap crops for the management of the fruit borer Helicoverpa armigera (Hubner) on tomato was evaluated. Initial experiments involved observational row trials with simultaneous planting/seeding of both tomato and trap crops in exploded blocks. One row of these crops was raised on either side and parallel to 10 and 15 rows of tomato respectively. Results indicated that use of African tall variety of marigold cv. Golden Age afforded maximum reduction of both eggs and larvae of H. armigera in the intercropped tomato with a consequent reduction in the number of bored fruits. The rest of the crops were ineffective because they were less preferred and also because flowering in these crops did not synchronize with tomato. Based on the success in observational row trials, systematic studies involving planting combinations of 10, 12, 14, 16, 18 and 20 rows of tomato were evaluated with one row of marigold planted on eit...

Movement and distribution pattern of the residues of granular insecticides in tropical soil and okra plants

SummaryThe increased downward mobility of phorate, quinalphos and carbofuran residues was detected in soil with increase in depth of soil column whereas aldicarb was found to remain localised mainly in 0–7.5 cm and 7.5–15.0 cm layers. Persistence of organophosphate insecticides was higher as compared to carbamates in all the soil layers. Residues of all the four insecticides got distributed in all parts of okra plant through uptake but accumulated in higher amounts in fruits only.

Diagnosis and management of bean flies in beans

Bean fly Ophiomyia phaseoli (Tryon) is a major pest of beans (Phaseolus vulgaris L.) in tropics (Spencer, 1973).Soil application of granular insecticides like phorate or foliar application of endosulfan are of effective against this pest (Krishna Moorthy and Tewari, 1987). These treatments are given as a. fixed schedule irrespective of the pest population. However, a. sound management programme requires understsanding of the biology of the pest. The biology of the pest is given by Goot (1930). The eggs are laid in ovipositional cavities, larvae mine the leaf. petiole and enter the stem. The pest is generally diagnosed in the stem. The early diagnostic characters of the pest incidence are punct ure marks, vein-mining and petiole mining. Of these, petiole mining thresholds (PMT) has been used for man aging the pest (Krishna Moorthy and Srinivasan, 1989). However, one application of insecticide based on PMT was not consistent in controlling the pest. The present paper reports the use of puncture marks and vein-mining in addition to PMT for the effective management of the pest in beans.

Distribution and larval behaviour of Lampides boeticus in vegetable lablab

The distribution pattern and larval behaviour of the major flower and pod borer Lampides Boeticus on vegetable lablab were studied in Bangalore, India. The distribution of eggs and bored flower buds were found to be contagious. Most of the flower buds with pin hole damage had small larva (first and second instar) inside them. Flower buds with medium damage had medium larva (third instar). The flower buds and pods with large damage very rarely harboured larva. The medium and large larvae migrated and caused damage to flower buds and pods. Use of larval behaviour in developing a suitable pest management programme is indicated.RésuméNous avons étudié à Bangalore la distribution et le comportement des larves de l’insecte perceur Lampides Boeticus qui ravage surtout les fleurs et les cosses des haricots légumiers lablab. La distribution des oeufs et des bourgeons percés se trouve contagieuse. La plupart des bourgeons avec des trous d’épingle avaient des petites larves (1 er et 2 e stades) dedans. Les bourgeons avec des dégâts moyens supportaient des larves de grosseur moyenne (3 e stades). Les bourgeons et les cosses avec des grands dégâts abritaient très rarement des larves. Les larves de grosseur moyenne et grande se déplaçaient et provoquaient des dégâts considérables aux bourgeons et cosses. Les larves semblaient préférer les bourgeons aux cosses. Sur la base du comportement des larves, nous indiquons des mesures convenables pour anter les insectes.

Action Thresholds for the Management of Pod-borer, Adisura atkinsoni Moore on Field Bean, Lablab purpureus

Management programmes for the use of action thresholds to initiate insecticide treatments for controlling pod-borer, Adisura atkinsoni on field bean were evaluated in comparison with standard sprays on calendar basis. Results of three field experiments revealed that management based on initial spray at peak egg laying on tender pods, followed by sprays to maintain 1.5 flat pod damage/inflorescence realised maximum benefit: cost ratio. This management also resulted in reduced insecticide usage.RésuméNous avons comparé des programmes d’emploi des insecticides pour limiter l’insecte perceur, Adisura atkinsoni, sur les haricots de champs, Lablab purpureus, basés sur la notion de seuils d’action avec des programmes classiques de pulvérisations d’insecticides périodiques. Les résultats obtenus de trois essais aux champs ont montré que le programme comprenant une pulvérisation initiale d’insecticide à l’époque de ponte maximale d’oeux sur les cosses tendres suivie de pulvérisations pour maintenir les dégâts à un taux de 1.5 cosses plates percées par inflorescence donnait le rapport maximal de bénefices aux coûts. Ce programme conduisait également à une reduction de la consommation d’insecticide.

Spatial distribution of eggs laid and pods bored by Adisura atkinsoni (Moore) (Noctuidae: Lepidoptera) in field bean

Distribution patterns of the critical stages of the major pod borer, Adisura atkinsoni (Moore) of field bean were studied at Bangalore, India. Eggs of A. atkinsoni and the pods damaged by its caterpillar followed negative binomial distribution. Eggs were distributed mostly on tender pods and those on tender pods (< 0.5 cm wide) were highly correlated with total number of eggs laid on the inflorescence. Flat bored pods of 0.6-1.5 cm width were highly correlated with total number of bored pods per inflorescence. Compared with matured bored pods, flat pods also had more borers inside. 69.23% of the matured bored pods were without borers. Hence it is suggested that the eggs on tender pods and borer damage on flat pods, should both be observed before control measures are initiated.RésuméNous avons étudié à Bangalore des modèles de distribution des stades critiques de l’insecte perceur dit Adisura atkinsoni (Moore) qui ravage le plus les haricots de champs (Lablab purpureus). Les oeufs des insectes A. atkinsoni et les cosses détruites par les chenilles de ces insectes suivaient une distribution binomiale negative. Le rapport de la variance à la moyenne et les valeurs de K montraient également la tendance de ces insectes à se grouper. Les oeufs étaient distribués surtout sur les cosses tendres et le nombre d’oeufs déposés sur les cosses tendres (<0,5cm de largeur) était sensiblement correlé avec le nombre total des oeufs déposés sur l’inflorescence. Le nombre de cosses plates et percées de largeur de 0,6-1,5 cm était sensiblement correlé avec le nombre total de cosses percées pour chaque inflorescence. En comparaison avec les cosses mûres et percées, les cosses plates avaient plus des insectes perceurs à l’intérieur. 69,23% des cosses mûres percées étaient sans insectes perceurs. Nous suggérons donc que l’on devrait observer les oeufs sur les cosses tendres ainsi que les dégâts causés par les insectes sur les cosses plates avant de commencer toutes mesures de contrôle.